Soufrière Hills

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  • Last Known Eruption
  • 16.72°N
  • 62.18°W

  • 915 m
    3001 ft

  • 360050
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1 May-7 May 2013

MVO reported that during 26 April-3 May activity at the Soufrière Hills lava dome was at a low level. During 1-2 May the wind direction shifted to the N and NE, blowing the plume over inhabited areas where residents occasionally reported volcanic-gas odors. The Hazard Level remained at 2 (on a scale of 1-5).

Source: Montserrat Volcano Observatory (MVO)



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1 May-7 May 2013

MVO reported that during 26 April-3 May activity at the Soufrière Hills lava dome was at a low level. During 1-2 May the wind direction shifted to the N and NE, blowing the plume over inhabited areas where residents occasionally reported volcanic-gas odors. The Hazard Level remained at 2 (on a scale of 1-5).

Source: Montserrat Volcano Observatory (MVO)


24 April-30 April 2013

MVO reported that during 19-26 April activity at the Soufrière Hills lava dome was at a low level. There had been no good views of the lava dome for over a month, but reports from helicopter pilots suggested that the most of the large slab that was on the E side of the lava dome was gone, likely removed during the pyroclastic flow on 28 March. The Hazard Level remained at 2 (on a scale of 1-5).

Source: Montserrat Volcano Observatory (MVO)


27 March-2 April 2013

MVO reported that during 22-29 March activity at the Soufrière Hills lava dome was at a low level. A pyroclastic flow traveled down the Tar River Valley (E) at about 0500 on 28 March. The flow was not observed directly, but the deposits indicated that it traveled halfway down the valley, 1-1.5 km from the dome. There were no reports of ashfall; any ash was probably blown over Plymouth and out to sea. The source of the flow was not known due to cloud cover, but was likely from the failure a large slab that had been slowing moving away from the dome. Heavy rainfall during the evening of 28 March generated large lahars in several valleys around the volcano, including in the Belham Valley (NW). These started at about 1900 and lasted for several hours. The Hazard Level remained at 2 (on a scale of 1-5).

Source: Montserrat Volcano Observatory (MVO)


13 March-19 March 2013

MVO reported that during 8-15 March activity at the Soufrière Hills lava dome was at a low level. During a helicopter overflight on 8 March, scientists observed a large fissure in the cliff on the E side of the lava dome, part of which had existed since 2007. This fissure was the result of slow cooling and erosion of the dome. It was parallel to the cliff face and estimated to be 2 m wide, suggesting that a large slab was slowing moving away from the dome. The Hazard Level remained at 2 (on a scale of 1-5).

Source: Montserrat Volcano Observatory (MVO)


20 February-26 February 2013

MVO reported that during 15-22 February activity at the Soufrière Hills lava dome was at a low level and sulfur dioxide gas flux returned to baseline levels, similar to the levels measured before the activity that occurred between 3 and 6 February. The Hazard Level remained at 2 (on a scale of 1-5).

Source: Montserrat Volcano Observatory (MVO)


13 February-19 February 2013

MVO reported that during 8-15 February activity at the Soufrière Hills lava dome was at a low level, although sulfur dioxide gas flux remained elevated following the activity during 3-6 February. The seismic network recorded one rockfall and one volcano-tectonic earthquake. The Hazard Level remained at 2 (on a scale of 1-5).

Source: Montserrat Volcano Observatory (MVO)


6 February-12 February 2013

MVO reported that during 1-8 February activity at the Soufrière Hills lava dome was at a low level, although there was a slight increase during 3-6 February characterized by volcano-tectonic earthquakes, elevated gas flux, and possible light ash venting. The volcano-tectonic earthquakes occurred in four brief swarms: at 2220 on 3 February, at 0915 and 0950 on 4 February, and at 0620 on 5 February. The second swarm was the most intense, and was followed by a hybrid seismic event. Another hybrid event was not associated with a swarm.

After the second, and largest, volcano-tectonic swarm on 4 February, there were increases in the temperatures of several fumaroles inside the 11 February 2010 collapse scar, as observed using a handheld thermal infra-red camera at MVO, 5.7 km away. There was a further increase, as well as some loud roaring sounds, around the time of the third swarm. The activity likely included minor ash venting from a large fumarole in the floor of the collapse scar because fresh ash deposits were observed adjacent to this fumarole on the morning of 5 February. All fumaroles had returned to background levels of activity and temperature by later that day.

Sulfur dioxide measurements showed an average flux of 929 tonnes/day during the week, with a maximum of 2,381 tonnes/day and a minimum of 273. The flux was not steady, with peaks of 962, 1,266 and 2,381 on 1, 4 and 6 February, respectively. The last measurement is the highest daily value since the ash-venting episode that occurred during 23-25 March 2012. The Hazard Level remained at 2 (on a scale of 1-5).

Source: Montserrat Volcano Observatory (MVO)


19 September-25 September 2012

MVO reported that during 14-21 September activity at the Soufrière Hills lava dome was at a low level, although multiple rockfalls originated from the W side of the lava dome. The largest event generated a pyroclastic flow that traveled 1 km. Overhanging areas on both on the E and W faces of the dome were observed. The Hazard Level remained at 2 (on a scale of 1-5).

Source: Montserrat Volcano Observatory (MVO)


5 September-11 September 2012

MVO reported that during 31 August-7 September activity at the Soufrière Hills lava dome was at a low level, although seismicity remained slightly elevated. Clear views of parts of the dome showed very little change, apart from some modification to the steep eastern face from the formation of the pyroclastic flow on 29 August. The Hazard Level remained at 2 (on a scale of 1-5).

Source: Montserrat Volcano Observatory (MVO)


29 August-4 September 2012

MVO reported that during 24-31 August activity at the Soufrière Hills lava dome was at a low level, although seismicity remained slightly elevated. At 1545 on 29 August a small pyroclastic flow traveled 1-1.5 km E down the Tar River Valley. The flow lasted 75 seconds, generated an ash cloud that rose 900-1,200 m and drifted W over Plymouth, and had an extensive fine-grained surge component. The Hazard Level remained at 2 (on a scale of 1-5).

Source: Montserrat Volcano Observatory (MVO)


22 August-28 August 2012

MVO reported that during 13-20 July activity at the Soufrière Hills lava dome was generally at a low level. Seismicity had slightly increased, and was at the highest level since the ash-venting episode in March, but remained consistent with a pause in lava extrusion. The Hazard Level remained at 2 (on a scale of 1-5).

Source: Montserrat Volcano Observatory (MVO)


8 August-14 August 2012

MVO reported that during 3-10 August activity at the Soufrière Hills lava dome was mostly at a low level. The seismic network detected two small swarms of volcano-tectonic earthquakes on 7 and 8 August. Scientists at MVO observed a period of ash venting that began at 1700 on 8 August, less than two hours after the second swarm. Roaring sounds were heard at the same time. The ash plume drifted W over Plymouth at an altitude of about 1 km (3,280 ft) a.s.l., and a small amount of ashfall was reported by a fisherman offshore. The source of the venting appeared to be the gas vent in the floor of the 11 February 2010 collapse scar, and not the crater created on 23 March 2012.

On 9 August the inside of the collapse scar was partially visible during a helicopter flight. Fumarolic activity in the 23 March crater had increased compared to two weeks ago, and some other fumaroles were also more active. A change in wind direction shifted the volcanic plume N for much of the day and the odor of volcanic gas was noticeable in some inhabited areas. The Hazard Level remained at 2 (on a scale of 1-5).

Source: Montserrat Volcano Observatory (MVO)


18 July-24 July 2012

MVO reported that during 13-20 July activity at the Soufrière Hills lava dome was at a low level. Heavy rain on the morning of 19 July generated lahars in several valleys on the W flank of the volcano. Lahars in the Belham valley (NW) were small and restricted to the upper reaches of the valley. The Hazard Level remained at 2 (on a scale of 1-5).

Source: Montserrat Volcano Observatory (MVO)


11 July-17 July 2012

MVO reported that during 6-13 July activity at the Soufrière Hills lava dome was at a low level. Mild roaring was heard in nearby locations. A few small pyroclastic flows occurred on the E side of the lava dome, at the head of the Tar River Valley, and traveled less than 1 km. The Hazard Level remained at 2 (on a scale of 1-5).

Source: Montserrat Volcano Observatory (MVO)


9 May-15 May 2012

MVO reported that during 4-11 May activity at the Soufrière Hills lava dome was at a low level. Multiple areas of incandescence on the lava dome, at temperatures greater that 500 degrees Celsius, were visible on 5 May. Heavy rains on 10 May generated a small lahar in the Belham Valley (NW). The Hazard Level remained at 2 (on a scale of 1-5).

Source: Montserrat Volcano Observatory (MVO)


2 May-8 May 2012

MVO reported that the cloud cover which often obscures views of the Soufrière Hills lava dome cleared for a short period on 5 May, revealing multiple areas of incandescence, the same ones first observed on 11 November 2011. Some of the areas were visible to the naked eye while more were visible in a long-exposure photograph. Many of the bright areas were related to fumaroles. The Hazard Level remained at 2 (on a scale of 1-5).

Source: Montserrat Volcano Observatory (MVO)


25 April-1 May 2012

MVO reported that during 20-27 April activity at the Soufrière Hills lava dome was at a low level. Observations on 24 April revealed fresh rockfall and pyroclastic flow deposits SW, at the head of Gingoe's Ghaut. The Hazard Level remained at 2.

Source: Montserrat Volcano Observatory (MVO)


4 April-10 April 2012

MVO reported that during 30 March-6 April activity at the Soufrière Hills lava dome was generally at a low level and no ash-venting episodes had been detected since 23 March. The average sulfur dioxide emission rate measured during the week was 529 tonnes per day with a minimum of 200 and a maximum of 1,033. Scientists aboard a helicopter overflight on 4 April observed a new vent which had formed on 23 March; it was 30-50 m across and on the W side of the crater floor. The Hazard Level remained at 2.

Source: Montserrat Volcano Observatory (MVO)


28 March-3 April 2012

MVO reported that during 24-30 March activity at the Soufrière Hills lava dome was generally at a low level and no ash-venting episodes had been detected since 23 March. The average sulfur dioxide emission rate measured during the week was 1,320 tonnes per day with a minimum of 264 and a maximum of 4,594, which was the third-highest value recorded in the last ten years. High values occurred between 24 and 26 March, averaging 2,550 tonnes per day over the three days. The average for the rest of the week was around 400 tonnes per day. The Hazard Level remained at 2.

Source: Montserrat Volcano Observatory (MVO)


21 March-27 March 2012

MVO reported that during 16-23 March activity at the Soufrière Hills lava dome was at a low level, although seismicity increased. Two swarms of volcano-tectonic earthquakes occurred, the first between 1604 and 1651 on 22 March (49 events) and the second between 0310 and 0527 on 23 March (54 events). Earthquakes in the second swarm were markedly larger than those in the first. Several changes on the volcano were observed on 23 March; fumarolic activity had increased and a new fumarole had appeared on the NW face of the lava dome behind Gages Mountain. In addition a vent producing pulsing steam emissions with a small amount of ash had formed in the back of the February 2010 collapse scar. Ash plumes rose 1.8 km (6,000 ft) a.s.l. and very light ashfall occurred on the W flank of the volcano. Audible roaring associated with the venting was heard intermittently from MVO, 5.75 km NW of the volcano. The Hazard Level remained at 2.

Based on a METAR weather report and analyses of satellite imagery, the Washington VAAC reported that on 24 March a gas-and-ash plume drifted 65 km WSW. Later that day the VAAC reported a detached area of ash drifting NW and a second small emission of ash drifting WNW. The next day haze and vog W of Soufrière Hills was detected in satellite imagery and a pilot reported ash at altitudes of 1.5-3 km (5,000-10,000 ft) a.s.l. drifting NW.

On 26 March MVO noted that activity returned to a low level following the ash-venting on 23 March. The report noted that Zone C on the volcanic risk map, which was temporarily closed the previous week due to an increase in volcano-tectonic earthquakes below Soufrière Hills, re-opened for day-time entrance on 27 March. Zone C is to the WNW of Soufrière Hills and includes Cork Hill, Weekes, Foxes Bay, Richmond Hill, and Delvins, and extends 500 m out to sea.

Sources: Washington Volcanic Ash Advisory Center (VAAC), Montserrat Volcano Observatory (MVO)


14 March-20 March 2012

MVO reported that on 9 March at 1720 a small pyroclastic flow from the Soufrière Hills lava dome traveled about 1.75 km W down Spring Ghaut and produced a small ash cloud that rose 1.2 km and drifted W. During 9-16 March activity was at a low level. The Hazard Level remained at 2.

Source: Montserrat Volcano Observatory (MVO)


1 February-7 February 2012

MVO reported that during 27 January-3 February activity at the Soufrière Hills lava dome was at a low level. On 28 January a pyroclastic flow from the W side of the lava dome traveled 300 m. The Hazard Level remained at 2.

Source: Montserrat Volcano Observatory (MVO)


25 January-31 January 2012

MVO reported that during 20-27 January activity at the Soufrière Hills lava dome was at a low level. Small areas of incandescence emanated from the lava dome at night, similar to observations noted in recent months. On 27 January a small lahar descended from the W side of the lava dome. The Hazard Level remained at 2.

Source: Montserrat Volcano Observatory (MVO)


2 November-8 November 2011

MVO reported that during 28 October-4 November activity at the Soufrière Hills lava dome was at a low level. On 4 November the Hazard Level was lowered to 2 because of a considerable reduction in the number of spontaneous pyroclastic flows from the remaining lava dome over approximately the last year. The reduction in Hazard Level allowed people to have daytime access to Zone C to the W of the lava dome, including Cork Hill, Weekes, Richmond Hill, Delvins, and Foxes Bay. Other minor changes to hazard zone borders were also implemented.

Source: Montserrat Volcano Observatory (MVO)


21 September-27 September 2011

MVO reported that during 16-23 September activity at the Soufrière Hills lava dome was at a low level. On 19 September a pyroclastic flow occurred from the W side of the lava dome. The Hazard Level remained at 3.

Source: Montserrat Volcano Observatory (MVO)


8 June-14 June 2011

MVO reported that during 3-10 June activity at the Soufrière Hills lava dome was at a low level. Unusual wind directions caused a sulfur odor in inhabited areas multiple times during the reporting period. On 9 June a pyroclastic flow traveled down the S flank, the first to go S in more than a year. The pyroclastic flow generated an ash cloud that drifted N and caused light ashfall in NW Montserrat. The Hazard Level remained at 3.

Source: Montserrat Volcano Observatory (MVO)


18 May-24 May 2011

MVO reported that during 13-20 May activity at the Soufrière Hills lava dome was at a low level. On 15 May a pyroclastic flow that occurred in the February 2010 collapse scar caused light ashfall in inhabited areas. The Hazard Level remained at 3.

Source: Montserrat Volcano Observatory (MVO)


11 May-17 May 2011

MVO reported that during 6-13 May activity at the Soufrière Hills lava dome was at a low level. On 11 May a pyroclastic flow that occurred in the February 2010 collapse scar traveled about 1 km. An ash cloud rose 1.8 km and drifted NNE, causing light ashfall in Lookout village. The Hazard Level remained at 3.

Source: Montserrat Volcano Observatory (MVO)


13 April-19 April 2011

MVO reported that during 8-15 April activity at the Soufrière Hills lava dome was at a low level. On 11 April a piece of the E side of the lava dome broke off and generated a small pyroclastic flow that traveled at most 1.5 km down the Tar River valley to the E. A resulting ash plume drifted W over uninhabited areas. The Hazard Level remained at 3.

Source: Montserrat Volcano Observatory (MVO)


30 March-5 April 2011

MVO reported that during 25 March-1 April activity at the Soufrière Hills lava dome was at a low level. A swarm of 36 earthquakes occurred within an hour on 28 March, the largest volcano-tectonic swarm since February 2010. The Hazard Level remained at 3.

Source: Montserrat Volcano Observatory (MVO)


23 March-29 March 2011

MVO reported that during 18-25 March activity at the Soufrière Hills lava dome was at a low level. A small lahar occurred in the Belham valley (NW) on 19 March. A relatively large pyroclastic flow traveled likely in excess of 2 km down the Tar River valley to the E and a resulting ash plume drifted W over uninhabited areas. The pyroclastic flow was related to the degradation of the lava dome on the E side as recent observations noted undercutting and overhanging areas on that side. The Hazard Level remained at 3.

Source: Montserrat Volcano Observatory (MVO)


2 March-8 March 2011

MVO reported that during 25 February-4 March activity at the Soufrière Hills lava dome was at a low level. Clear views from a helicopter on 3 March revealed modest changes in the lava dome; continued degradation of the W face was evident and the E face showed undercutting with overhanging areas. Small areas of incandescence were visible on the N face of the dome during clear evenings. The Hazard Level remained at 3.

Source: Montserrat Volcano Observatory (MVO)


23 February-1 March 2011

MVO reported that during 18-25 February activity from the Soufrière Hills lava dome was at a low level. Of 31 volcano-tectonic earthquakes detected by the seismic network, 18 occurred in a small swarm on 23 February. On 24 February a pyroclastic flow that traveled less than 1.5 km on the N flank originated from one of the highest parts of the dome, and travelled down the collapse scar formed on 11 February. The event produced an extensive pyroclastic surge and a relatively strong ash plume that rose to an altitude of about 1.5 km (5,000 ft) a.s.l. The Hazard Level remained at 3.

Source: Montserrat Volcano Observatory (MVO)


16 February-22 February 2011

MVO reported that on 15 February clear views of the Soufrière Hills lava dome allowed scientists to conduct a thermal survey, the first since 2 December 2010, and compare the results to identify changes. A warmer area on the W side of the lava dome (Gages) had moved upslope. This area had been the source of a number of pyroclastic flows and rockfalls since February 2010. The second difference was the apparent increase in the number of fumaroles inside the collapse scar and around the 2006-2007 dome. One of the most obvious areas of increase was on the NE side of the lava dome.

MVO also reported that in total 18 volcano-tectonic earthquakes from Soufrière Hills were detected in two swarms that occurred on 12 and 16 February. Brief clear views of the lava dome revealed no significant morphological changes. Fresh pyroclastic-flow deposits on the E side of the dome at the head of the Tar River valley were noted. The Hazard Level remained at 3.

Source: Montserrat Volcano Observatory (MVO)


9 February-15 February 2011

MVO reported that during 4-11 February activity from the Soufrière Hills lava dome was at a low level. Helicopter observations revealed fresh pyroclastic-flow deposits about 1.5 km long in the Tar River valley to the E that formed on 10 February. The pyroclastic flow had an extensive surge component that inundated the lower flanks of Roaches Mountain. Clouds prevented observations of the lava dome. The Hazard Level remained at 3.

Source: Montserrat Volcano Observatory (MVO)


12 January-18 January 2011

MVO reported that during 7-14 January activity from the Soufrière Hills lava dome was at a low level. Helicopter observations revealed fresh pyroclastic-flow deposits less than 1 km long on the E side of the lava dome. A small pyroclastic flow occurred at the head of the Tar River valley to the E on 6 January. The Hazard Level remained at 3.

Source: Montserrat Volcano Observatory (MVO)


5 January-11 January 2011

MVO reported that during 31 December 2010-7 January 2011 activity from the Soufrière Hills lava dome was at a low level. A small lahar descended the Belham valley (NW) on 5 January. Gas measurements on 6 January indicated that the ratio of hydrochloric acid to sulfur dioxide was 0.29, a ratio similar to those measured over the last few months and consistent with no lava extrusion. Helicopter observations that same day showed marked acid rain damage in the Spring (W) and Gingoes (SW) ghaut areas, up to 3 km from the lava dome. Cloudy weather prevented observations of the lava dome. The Hazard Level remained at 3.

Source: Montserrat Volcano Observatory (MVO)


29 December-4 January 2011

MVO reported that during 24-31 December activity from the Soufrière Hills lava dome was at a low level. Rockfalls or small pyroclastic flows detected by the seismic network occurred in the 11 February collapse scar on the N side of the volcano. Clouds prevented clear views of the lava dome. Lahars associated with heavy rains descended multiple drainages on 30 December. The Hazard Level remained at 3.

Source: Montserrat Volcano Observatory (MVO)


22 December-28 December 2010

MVO reported that during 17-24 December activity from the Soufrière Hills lava dome was at a low level. A small pyroclastic flow traveled 1.5 km down the Gages valley to the W on 19 December. The Hazard Level remained at 3.

Source: Montserrat Volcano Observatory (MVO)


15 December-21 December 2010

MVO reported that during 10-17 December activity from the Soufrière Hills lava dome was at a low level. Several small pyroclastic flows descended gages valley to the W. The largest pyroclastic flow occurred on 15 December and travelled about 1.5 km. A small number of rockfalls occurred in the 11 February collapse scar. The Hazard Level remained at 3.

Source: Montserrat Volcano Observatory (MVO)


8 December-14 December 2010

MVO reported that during 3-10 December activity from the Soufrière Hills lava dome was at a low level. Observations from helicopter revealed fresh rockfall and pyroclastic flow deposits in the Tar River valley (E) that originated from the E face of the lava dome. On 6 December a small pyroclastic flow occurred in the 11 February collapse scar. The next day a small lahar occurred in the upper part of the Belham valley to the NW. The Hazard Level remained at 3.

Source: Montserrat Volcano Observatory (MVO)


1 December-7 December 2010

MVO reported that during 26 November-3 December activity from the Soufrière Hills lava dome was at a low level. Part of the large unstable overhanging area on the W side of the lava dome collapsed on 29 November, generating pyroclastic flows that traveled about 2 km W. Small pyroclastic flows also occurred on the E side of the dome. On 2 December, small areas of incandescence were visible on the back wall of the 11 February collapse scar. The Hazard Level remained at 3.

Source: Montserrat Volcano Observatory (MVO)


10 November-16 November 2010

MVO reported that during 5-12 November activity from the Soufrière Hills lava dome was at a low level. Photographs from 11 November showed areas of nighttime incandescence from the lava dome, indicating that although extrusion stopped nine months earlier, the lava dome remained hot. Small pyroclastic flows occurred in the Tar River valley to the E on 6 November and from the N side of the dome on 9 November. Light ashfall associated with the 9 November event occurred in inhabited areas of N Montserrat. Helicopter observations revealed that the overhanging part of the dome on the W side, immediately E of Chances Peak, was more pronounced by further undercutting of rockfalls and pyroclastic flows. The Hazard Level remained at 3.

Source: Montserrat Volcano Observatory (MVO)


3 November-9 November 2010

MVO reported that during 29 October-5 November activity from the Soufrière Hills lava dome was at a low level. The largest pyroclastic flow occurred on 5 November and traveled 1.5 km W down Gages valley. The Hazard Level remained at 3.

Source: Montserrat Volcano Observatory (MVO)


13 October-19 October 2010

MVO reported that during 8-15 October activity from the Soufrière Hills lava dome was at a low level. Light ashfall generated by rockfalls and pyroclastic flows occurred in inhabited areas of Montserrat mainly during 8-10 October. A pyroclastic flow originating from an unstable area on the W side of the lava dome traveled 2 km on 9 October. The Hazard Level remained at 3.

Source: Montserrat Volcano Observatory (MVO)


6 October-12 October 2010

MVO reported that during 1-8 October activity from the Soufrière Hills lava dome was at a low level. A pyroclastic flow traveled W down Gages Valley and into Spring Ghaut on 2 October. Several lahars flowed down the Belham valley to the NW. According to the Washington VAAC, MVO reported that an ash plume rose to an altitude of 2.1 km (7,000 ft) a.s.l. and drifted W. The next day an ash plume seen in satellite imagery drifted 55 km WNW and NW. A few hours later an area of ash at an altitude of 2.1 km (7,000 ft) a.s.l. was seen 140 km WNW. On 11 October a diffuse steam-and-gas plume drifted NNW. The Hazard Level remained at 3.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


29 September-5 October 2010

MVO reported that during 24 September-1 October activity from the Soufrière Hills lava dome was at a low level. Several pyroclastic flows originating from the W side of the lava dome moved W down Gages Valley and into Spring Ghaut. The largest pyroclastic flow traveled approximately 2 km. The Hazard Level remained at 3.

Source: Montserrat Volcano Observatory (MVO)


22 September-28 September 2010

MVO reported that during 17-24 September activity from the Soufrière Hills lava dome was at a low level. Heavy rains caused lahars during 19-20 September in the Belham valley to the NW. One pyroclastic flow traveled 1.5 km E down the Tar River valley on 21 September. The Hazard Level remained at 3.

Source: Montserrat Volcano Observatory (MVO)


8 September-14 September 2010

MVO reported that several small-to-moderate sized pyroclastic flows from Soufrière Hills during 3-10 September removed parts of the cold dome carapace, resulting in the thermal camera displaying several hotter regions on the lava dome. The largest pyroclastic flow traveled 2.5 km down the Gages valley to the W on 9 September. The Hazard Level remained at 3.

Source: Montserrat Volcano Observatory (MVO)


25 August-31 August 2010

MVO reported that most of the rockfalls and pyroclastic flows detected during 20-27 August originated from a vertical face on the SE side of the lava dome and traveled W down Gages valley and E down the Tar River valley. The pyroclastic flows traveled no longer than 1.5 km and produced weakly convecting ash clouds that rose a few hundred meters. The Hazard Level remained at 3.

Source: Montserrat Volcano Observatory (MVO)


18 August-24 August 2010

MVO reported most of the rockfalls and pyroclastic flows detected during 13-20 August originated from the W side of the lava dome and traveled W down Gages valley. The pyroclastic flows traveled no longer than 2 km and produced weakly convecting ash clouds. A small lahar descended the Belham valley to the NW on 19 August. The Hazard Level remained at 3.

Source: Montserrat Volcano Observatory (MVO)


11 August-17 August 2010

MVO reported that mild ash-and-steam venting from Soufrière Hills as well as rockfalls were seen during 6-13 August. Most of the activity was focused in the collapse scar and above the Gages valley to the W. On 6 August a small ash plume rose 1 km above the lava dome, and on 8 August a pyroclastic flow descended Gages valley. The Hazard Level remained at 3.

Source: Montserrat Volcano Observatory (MVO)


4 August-10 August 2010

Based on a METAR weather report and analyses of satellite imagery, the Washington VAAC reported that on 10 August a narrow plume from Soufrière Hills drifted more than 100 km WNW.

Source: Washington Volcanic Ash Advisory Center (VAAC)


21 July-27 July 2010

MVO reported that activity at Soufrière Hills was low during 16-23 July and inclement weather prevented clear observations of the lava dome. Heavy rains generated a few lahars in the Belham valley to the NW. The largest occurred on 20 July and lasted about 40 minutes. The Hazard Level remained at 3.

Source: Montserrat Volcano Observatory (MVO)


14 July-20 July 2010

MVO reported that activity at Soufrière Hills was low during 9-16 July. Helicopter observations on 15 July revealed no major changes to the lava dome, although there were some fresh rockfall and small pyroclastic-flow deposits at the head of the Gages valley to the W. The next day, heavy rainfall generated a few lahars in the Belham valley to the NW. The Hazard Level remained at 3.

Source: Montserrat Volcano Observatory (MVO)


7 July-13 July 2010

MVO reported that small swarms of volcano-tectonic earthquakes from Soufrière Hills on 23 and 25 June were coincident with ash venting beginning on 25 June. Ash venting diminished on 28 June. A second period of ash venting took place on 2 July and was preceded by two volcano-tectonic and two long-period earthquakes. An emission of ash, with accompanying rumbling noises, formed a plume that drifted WNW and caused ashfall in uninhabited areas of Gages, Plymouth, and the Foxes Bay region. During 2-9 July, roaring was often heard. The Hazard Level remained at 3.

Source: Montserrat Volcano Observatory (MVO)


30 June-6 July 2010

On 28 June, MVO reported that for the first time since February 2010 ash venting from the Soufrière Hills lava dome was observed and caused light ashfall in several areas across Montserrat. Ash venting began on 25 June and was coincident with small swarms of volcano-tectonic earthquakes on 23 and 25 June, although with no other discernable associated seismicity. Observations initially from MVO staff and during a later overflight indicated that the ash venting occurred from inside the collapse scar (near the N rim of English's crater) and from the S part of the summit crater that had formed on 11 February. On the nights of 25 and 26 June audible roaring was heard from several locations on the island. Ash venting diminished on 28 June. The Hazard Level remained at 3.

Source: Montserrat Volcano Observatory (MVO)


16 June-22 June 2010

MVO reported that pyroclastic flows from the Soufrière Hills lava dome occurred during 11-18 June. One of the largest pyroclastic flows traveled W down Gages Valley; others originated from within the collapse scar. A thermal camera showed several hot areas on the lava dome, likely exposed from rockfall and pyroclastic flow activity. On 28 June a small lahar descended the Belham Valley, to the NW. The Hazard Level remained at 3.

Source: Montserrat Volcano Observatory (MVO)


9 June-15 June 2010

MVO reported that rockfalls and pyroclastic flows from the Soufrière Hills lava dome occurred during 4-11 June. The largest pyroclastic flow originated in the collapse scar and traveled 1 km N. The Hazard Level remained at 3.

Source: Montserrat Volcano Observatory (MVO)


12 May-18 May 2010

MVO reported that activity at Soufrière Hills was low during 7-14 May. A pyroclastic flow traveled as far as 2 km W down Gages Valley on 10 May. The Hazard Level remained at 3.

Source: Montserrat Volcano Observatory (MVO)


5 May-11 May 2010

MVO reported that activity at Soufrière Hills was low during 30 April-7 May. A pyroclastic flow traveled down the Tar River Valley on 3 May, stopping about 1 km before reaching the sea. The Hazard Level remained at 3.

Source: Montserrat Volcano Observatory (MVO)


14 April-20 April 2010

MVO reported that during 9-16 April activity at Soufrière Hills remained low. Several rockfalls occurred on the W side of the lava dome on 15 April, and a small pyroclastic flow occurred on the Gages fan on 16 April; both were probably caused by heavy rainfall. The rain also generated lahars (mudflows) on several flanks. On the afternoon of 13 April large lahars occurred in the Belham valley, creating two large fans at the coast. Many of the lahars were hot with abundant associated steam and geysering.

Source: Montserrat Volcano Observatory (MVO)


7 April-13 April 2010

MVO reported that during 2-9 April activity from the Soufrière Hills lava dome was at a low level. Rockfalls occurred sporadically from several areas of the lava dome. Multiple small areas of incandescence on the dome were visible several nights during the reporting period. Heavy rains on 2 April caused lahars in the Farm River and Trants area (NNE). The Hazard Level remained at 3.

Source: Montserrat Volcano Observatory (MVO)


31 March-6 April 2010

MVO reported that during 26 March-2 April activity from the Soufrière Hills lava dome was at a low level. Rockfalls and pyroclastic flows occurred sporadically on the W and S flanks. The Hazard Level remained at 3.

Source: Montserrat Volcano Observatory (MVO)


24 March-30 March 2010

MVO reported that during 19-26 March activity from the Soufrière Hills lava dome was at a low level. Small-to-moderate-sized pyroclastic flows on the W and S flanks occurred sporadically. The largest pyroclastic flow traveled 2 km W down Spring Ghaut on 25 March. The Hazard Level remained at 3.

Source: Montserrat Volcano Observatory (MVO)


17 March-23 March 2010

MVO reported that during 12-19 March activity from the Soufrière Hills lava dome was at a low level. Small incandescent areas on the dome were visually observed on 14 March. Occasional small pyroclastic flows and rockfalls occurred from the W and S parts of the dome. The Hazard Level remained at 3.

Source: Montserrat Volcano Observatory (MVO)


10 March-16 March 2010

MVO reported that heavy rains during 5-12 March caused vigorous steaming from hot deposits emplaced after part of the Soufrière Hills lava dome collapsed on 11 February. Geysers were visible at Trants near the old Bramble airport, about 5 km NE, along with ash and steam ejections. Lahars descended multiple drainages around the volcano. Cooled lava shed from the dome on 8 and 9 March due to the heavy rains caused a series of pyroclastic flows to travel W down Gages Valley on 9 March, as far as 2 km. Ashfall from the pyroclastic flows was noted in NE Montserrat. There was no evidence of fresh lava extrusion. The Hazard Level remained at 3.

Source: Montserrat Volcano Observatory (MVO)


3 March-9 March 2010

MVO reported that during 26 February-5 March activity from the Soufrière Hills lava dome was at a low level. A swarm of seven relatively large hybrid earthquakes was detected early on 4 March. Later that morning, two small pyroclastic flows descended the Tar River valley and caused ashfall in Salem and Olveston, 6-8 km NW. The Hazard Level remained at 3.

Source: Montserrat Volcano Observatory (MVO)


24 February-2 March 2010

MVO reported that during 19-26 February activity from the Soufrière Hills lava dome was at a low level. A few rockfalls originated from the inner walls of the collapse scar on the N flank, formed during the 11 February event. Small areas of incandescence on the dome were noted. Gas emission ratios were consistent with slow lava extrusion, but growth was unconfirmed. On 26 February scientists first saw the crater at the summit of the lava dome formed by explosions on 11 February. The crater was 200 m in diameter and 50-100 m deep. The Hazard Level was lowered to 3.

Source: Montserrat Volcano Observatory (MVO)


17 February-23 February 2010

MVO reported that during 12-19 February activity from the Soufrière Hills lava dome was at a low level. Rockfalls originated from the inner walls of the 300-m-wide collapse scar on the N flank, formed from the 11 February event, and from the dome summit. Gas measurements on 17 February and seismicity were consistent with lava-dome growth, but growth was unconfirmed.

Inspection of the deposits from the 11 February collapse event revealed that the NE coastline had extended into the sea an additional 650 m. Pyroclastic flows razed many buildings in both Harris (3 km N) and Streatham (2 km NNW), and destroyed trees in the Gun Hill area (2 km NNW). Pyroclastic-flow deposits were approximately 15 m thick in the Trants region of the coast (near the old Bramble airport, about 5 km NE). A deep crater, similar in diameter to the collapse scar, was seen in the summit of the lava dome. The Hazard Level remained at 4.

Source: Montserrat Volcano Observatory (MVO)


10 February-16 February 2010

MVO reported that during 5-12 February activity from the Soufrière Hills lava dome increased significantly. Activity was concentrated on the W side of the lava dome during the first part of the week then shifted to the N side on 9 February.

On 11 February part of the lava dome collapsed leaving a large collapse scar on the NE flank. Pyroclastic flows traveled NE and then, along with pyroclastic surges, across the sea at several places on the E side of Montserrat. Pyroclastic flow deposits covered several hundred meters of the coastline near the old Bramble airport, about 5 km NE. Pyroclastic flows also traveled NW into Tyers Ghaut and down the Belham valley as far a Cork Hill, 4 km NW. An ash plume rose to an altitude of 15.2 km (50,000 ft) a.s.l. and drifted E and then SE. Ashfall occurred in NE Montserrat, SW Antigua (50 km NW), Guadeloupe (65 km SE), and Dominica (145 km SE). According to news articles, flights in and out of the region were temporarily suspended due to the ash plumes.

Sources: Montserrat Volcano Observatory (MVO), Agence France-Presse (AFP)


3 February-9 February 2010

MVO reported that during 29 January-5 February activity from the Soufrière Hills lava dome was variable as the lava dome continued to grow. Cycles of vigorous ash venting, rockfalls, and pyroclastic flows occurred every seven to twelve hours. Pyroclastic flows traveled mostly W down Gages into Spring Ghaut, as far as 3 km, but also occurred in Whites Ghaut to the NE. Rockfall activity was abundant on the N flank. On 4 February, ash fell across NW Montserrat. Observations the next day revealed that the central W part of the lava dome had grown and was 1,070 m a.s.l.

Pyroclastic flows following a Vulcanian explosion on 5 February traveled W, reaching Plymouth and spreading 500 m across the sea. Pyroclastic flows also traveled as far as 2 km NW down Tyers Ghaut and NE down Whites Ghaut. An ash plume rose to an altitude of 6.4 km (21,000 ft) a.s.l. A small Vulcanian explosion on 8 February generated pyroclastic flows that mostly traveled W down Gages Valley. Small pyroclastic surges observed using a thermal camera descended the N flanks. An ash plume rose to an altitude of 4.6 km (15,000 ft) a.s.l. and drifted E and ENE. Ashfall was reported in NW Montserrat and in SW Antigua, 50 km NW. The Hazard Level remained at 4.

Source: Montserrat Volcano Observatory (MVO)


27 January-2 February 2010

MVO reported that during 22-29 January activity from the Soufrière Hills lava dome was variable as the lava dome continued to grow. Cycles of vigorous ash venting, rockfalls, and pyroclastic flows occurred every five to seven hours. Pyroclastic flows traveled down multiple valleys, including Whites Ghaut to the NE, and W down Gages into Spring Ghaut. The increasing number of pyroclastic flows that traveled E down the Tar River Valley, frequently reaching the sea, were attributed to new lava-dome growth in the SE part of the lava dome. Ash fell across most of Montserrat on 23 January. Vigorous steaming from hot pyroclastic flows emplaced in the Belham Valley on 8 January was caused by heavy rains on 25 January. Small steam explosions generated steam plumes that sometimes contained ash. The Hazard Level remained at 4.

Source: Montserrat Volcano Observatory (MVO)


20 January-26 January 2010

MVO reported that during 15-22 January activity from the Soufrière Hills lava dome was variable as dome growth continued. Cycles of vigorous ash venting, rockfalls, and pyroclastic flows occurred every six to eight hours. Light ashfall occasionally occurred in NW Montserrat. On 18 January, a small lava-dome collapse from the W side of the volcano generated a large pyroclastic flow that traveled 4 km down Gages Valley into Spring Ghaut, and into Aymer's Ghaut, reaching the sea at Kinsale to the S of Plymouth. Ash clouds associated with the pyroclastic flows rose to an altitude of 3 km (10,000 ft) a.s.l. Several houses in Kinsale seen from a helicopter on 22 January had been buried or were burning. The Hazard Level remained at 4.

Source: Montserrat Volcano Observatory (MVO)


13 January-19 January 2010

MVO reported that during 8-15 January activity from the Soufrière Hills lava dome increased significantly. One explosion on 8 January and two on 10 January generated ash plumes that rose to altitudes of 5.5-7.6 km (18,000-25,000 ft) a.s.l. Ash fell in occupied areas to the NW, along with lapilli fall on 10 January. The explosions occurred from an area on the NE side of the volcano. Pyroclastic flows from column collapses moved rapidly NE (down Whites Bottom and Tuitts Ghaut), NW (down Tyers Ghaut and Belham Valley), W (down Gages Ghaut), and the SE (down the Tar River Valley). After the explosions activity decreased until 12 January, when cycles of increased numbers of rockfalls, pyroclastic flows, and ash venting were noted.

Observations during 8-15 January revealed that lava-dome growth resumed at the top, central part of the dome. On 18 January, a partial lava-dome collapse generated a pyroclastic flow that traveled W down Gages Valley, into Spring Ghaut, and then WSW down Aymers Ghaut, reaching the sea. Ash plumes rose to an altitude of 3 km (10,000 ft) a.s.l. and drifted W. Smoke from burning houses in Kinsale was visible after the event. The Hazard Level remained at 4.

Source: Montserrat Volcano Observatory (MVO)


6 January-12 January 2010

MVO reported that during 31 December-8 January pyroclastic flows from the Soufrière Hills lava dome continued to travel predominantly down areas to the N including Whites Ghaut (NE), Farrells plain (N), and Tyers Ghaut (NW). Observations on 2 January showed that a 40-m-high, 150-m-wide lobe of lava had been extruded northwards onto the N summit of the dome. This lobe was the main source of rockfall and pyroclastic flow activity. On 3 and 4 January ash plumes rose to an altitude of 4.6 km (15,000 ft) a.s.l. and drifted NW. Ashfall occurred in areas to the NW several times during the reporting period.

On 8 January, a large pyroclastic flow event occurred after a collapsing fountain of tephra was observed on the NE side of the volcano. Pyroclastic flows traveled NE down Whites Bottom Ghaut to the sea and down Tuitts Ghaut to within a few hundred meters of the sea. Pyroclastic flows also traveled NW down Tyers Ghaut and into the Belham Valley, W towards Plymouth, and E down the Tar River valley. The event lasted about 11 minutes and seismicity returned to background levels quickly. There was no precursory seismicity associated with the event. Ashfall was reported in inhabited areas in the NW.

Seismic signals indicated that another explosion occurred on 10 January. Pyroclastic flows descended the NE, NW, and W flanks, and ashfall was reported in areas to the NW. Another explosion later that day also caused ashfall in inhabited areas. The Hazard Level remained at 4.

Source: Montserrat Volcano Observatory (MVO)


30 December-5 January 2010

MVO reported that during 24-31 December activity from the Soufrière Hills lava dome continued at a high level. Cycles of increased activity associated with vigorous ash venting and pyroclastic flows occurred every six to eight hours. Audible rockfalls, roaring, and occasional thunder were noted during the most intense events. Frequent pyroclastic flows traveled N down Whites Ghaut, Farrells plain, and Tyers Ghaut. Pyroclastic flows also traveled W down Gages Valley into Spring Ghaut, and occasionally to the S in Gingoes Ghaut. On 29 December several pyroclastic flows traveled 2.5 km, reaching Dyers village. A comparison of photographs from 30 December and 2 January revealed that the lava dome morphology had changed rapidly, with a significant addition of lava on the N side. The additional area of growth was approximately 60 m high and 100 m wide. The Hazard Level remained at 4.

Source: Montserrat Volcano Observatory (MVO)


23 December-29 December 2009

MVO reported that during 11-19 December activity from the Soufrière Hills lava dome continued at a high level. Observations with a high-resolution thermal camera revealed multiple rockfall channels on the W, NW, N, and NE flanks of the lava dome. Frequent pyroclastic flows were noted on the northern flank; pyroclastic flows traveled 3 km W down Gages Valley into Spring Ghaut, as far as 4 km NE down the White River valley, and as far as 2 km in Tyers Ghaut (NW). Occasional pyroclastic flows descended Gingoes Ghaut (S) and Tar River valley (E). Heavy ashfall was reported in many inhabited areas of Montserrat. Ashfall also occurred on many other Caribbean islands, as far as Puerto Rico (400 km ENE). The Hazard Level remained at 4. According to a news article on 29 December, about 45 commercial flights scheduled to arrive at or depart from Puerto Rico were cancelled due to ash in the area.

Sources: Montserrat Volcano Observatory (MVO), Associated Press


16 December-22 December 2009

MVO reported that during 11-19 December activity from the Soufrière Hills lava dome continued at a high level. Night-time incandescence and observations with a high resolution thermal camera showed that activity was concentrated on the NW flank. Pyroclastic flows and semi-continuous rockfalls traveled down the NE, N, and NW flanks, channelling NE directly into Whites Ghaut and continuing into Whites Bottom Ghaut. Pyroclastic flows also traveled as far as 2 km NW down Tyers Ghaut multiple times a day, occasionally as far as 2 km W down Gages valley, and rarely E down Tar River valley. Fresh deposits from small pyroclastic flows moving S were seen at the head of the White River and Gingoes Ghaut. On 19 December heavy ashfall occurred in several areas in NW Montserrat. The Hazard Level remained at 4.

Source: Montserrat Volcano Observatory (MVO)


9 December-15 December 2009

MVO reported that during 4-11 December activity from the Soufrière Hills lava dome continued at a high level and pyroclastic flow activity was concentrated on the N side. Pyroclastic flows traveled as far as 2 km NW into Tyers Ghaut and NE in abundance down Tuitt's Ghaut, and sometimes Whites Bottom Ghaut, continuing onto Farrell's plain. A few small pyroclastic flows also descended the Tar River valley to the E. On 10 December, a large seismic signal was associated with a relatively large pyroclastic flow in Tyers Ghaut that traveled 3.5 km, stopping just beyond the W end of Lee's village. The event prompted the National Disaster Preparedness and Response Advisory Committee (NDPRAC) to raise the Hazard Level to 4, restricting the hours residents can enter certain pre-designated hazard areas.

Source: Montserrat Volcano Observatory (MVO)


2 December-8 December 2009

MVO reported that during 27 November-4 December activity from the Soufrière Hills lava dome continued at a high level. Pyroclastic flow activity was concentrated to the NE and W. The largest pyroclastic flows traveled NE down Tuitt's Ghaut on 27 November and 2 December, reaching within 200 m of the sea. Associated ash plumes rose to altitudes of 4.6-6.1 km (15,000-20,000 ft) a.s.l. Pyroclastic flows also traveled W down Gages Valley, S down the White River valley and Gingoes Ghaut, and into the upper reaches of Tyers Ghaut (NW). One descended the Tar River valley to the E. Rockfalls cascaded directly from the summit of the lava dome into Tyers Ghaut. Ash venting from the S part of the lava dome was noted several times. Ashfall containing accretionary lapilli, reported from Salem, Old Towne, and parts of Olveston on the evening of 27 November, was associated with a pyroclastic flow down Tuitt's and White Bottom Ghaut. The Hazard Level remained at 3.

Source: Montserrat Volcano Observatory (MVO)


25 November-1 December 2009

MVO reported that during 20-27 November activity from the Soufrière Hills lava dome continued at a high level. Activity increased on 21 November and periods of tremor were detected on 23 November. Lava extrusion during this period shifted from the W side of the lava dome to the summit region. As a result, abundant pyroclastic flows traveled NE down Tuitt's Ghaut on 23 November for the first time in several weeks. On 24 November there was a period of 120 minutes of continuous pyroclastic flow activity, followed by 90 minutes of semi-continuous activity. The pyroclastic flows traveled W down Gages Valley and into Spring Ghaut, and NE down Tuitt's Ghaut and Whites Bottom Ghaut reaching Tuitt's village. Associated ash plumes rose to an altitude of 6.1 km (20,000 ft) a.s.l. On 26 November, a pyroclastic flow that descended the Tar River valley was caused by collapse of part of the old, pre-2009 lava dome. Ashfall occurred in Old Towne and parts of Olveston. Incandescent material seen in a photograph taken at night on 29 November traveled down the flanks of the lava dome in several areas. The Hazard Level remained at 3.

Source: Montserrat Volcano Observatory (MVO)


18 November-24 November 2009

MVO reported that during 13-20 November activity from the Soufrière Hills lava dome consisted of ash venting along with semi-continuous rockfalls and pyroclastic flows that were concentrated on the W flank. Ashfall occurred across many areas of the island. Views of the lava dome on 16 November showed that the dome height had decreased because of collapses and that a deep channel had developed NE of Chances Peak. Pyroclastic flows in the Gages Valley (W) continued down Spring Ghaut and Aymer's Ghaut, and spread onto the alluvial fan below St. Georges Hill. On 19 November, heavy ashfall occurred to the NW between Old Towne and Brades. The Hazard Level remained at 3.

Source: Montserrat Volcano Observatory (MVO)


11 November-17 November 2009

MVO reported that during 6-13 November activity from the Soufrière Hills lava dome continued at a high level. Pyroclastic flows mainly occurred towards the W down Gages Valley and SW down Gingoes Ghaut. Good views of the lava dome on 9 and 10 November revealed that recent lava-dome growth was concentrated on the WSW side, immediately NE of Chances Peak; intense incandescence and rockfalls were noted at night. Ash fell across the Montserrat on 11 November, and about 6-8 km NW in Salem, Old Towne, Olveston, and Woodlands on 12 November. The largest pyroclastic flow during the reporting period, on 12 November, traveled WSW, nearly reaching the sea at Kinsale village. The Hazard Level remained at 3.

Source: Montserrat Volcano Observatory (MVO)


4 November-10 November 2009

MVO reported that during 30 October-6 November activity from the Soufrière Hills lava dome was at a high level; hybrid earthquakes were recorded for the first time since the renewal of activity in early October. Numerous pyroclastic flows occurred in most of the major drainage valleys. On 4 November, pyroclastic flows were seen from a helicopter traveling SW down Gingoes Ghaut to within 200 m of the sea. The frequency of pyroclastic flows increased on 5 November and particularly vigorous flows occurred in Tuitt's Ghaut to the NE. Ash fell in inhabited areas on a few occasions. Lahars descended the Belham Valley to the W several times. The Hazard Level remained at 3.

Source: Montserrat Volcano Observatory (MVO)


28 October-3 November 2009

MVO reported that during 23-30 October seismic activity from the Soufrière Hills lava dome was at a slightly lower level that the previous week. Numerous pyroclastic flows occurred in most of the major drainage valleys and rockfalls were concentrated in the S. Heavy rainfall caused lahars in the Belham Valley to the W. On 28 October, two pyroclastic flows traveled 2 km W down Gages Valley. On 29 October, a 40-m-high spine was seen protruding from the summit. Changes in lava-dome morphology seen on 30 October, and occurrences of pyroclastic flows traveling NE, indicated that growth was concentrated in the central part of the lava dome. The Hazard Level remained at 3.

Source: Montserrat Volcano Observatory (MVO)


21 October-27 October 2009

MVO reported that during 16-25 October activity from the Soufrière Hills lava dome was at a high level; a new lava dome first reported on 9 October continued to grow in the summit region on the W side. The new dome was considerably higher than the older lava dome that is to the E. Seismicity was high and cycles of low-level tremor occurred at regular intervals. Several pyroclastic flows descended the White River to the S and reached the sea. Small pyroclastic flows traveled NE down Tuitts Ghaut and W down Gages valley, but seldom to the N down Tyers Ghaut or E down the Tar River valley. Rockfalls occurred on the S and SE flanks of the lava dome. Multiple ashfalls were reported in inhabited areas, and lahars traveled NW down the Belham valley. During 23-25 October, seismicity decreased and ash plumes generated by pyroclastic flows drifted W. The Hazard Level remained at 3.

Source: Montserrat Volcano Observatory (MVO)


14 October-20 October 2009

MVO reported that during 9-16 October activity from the Soufrière Hills lava dome was at a high level; a new lava dome first reported on 9 October continued to grow. Over 1,200 rockfalls were detected by the seismic network. Pyroclastic flows traveled down every major drainage valley except the Tar River valley to the E. Brief views of the lava dome revealed that the new lava dome summit was about 60 m above the old dome structure. Heavy rainfall caused a lahar in the Belham Valley to the NW on 14 October. On 16 October, several large pyroclastic flows descended the White River to the S and reached the sea. Moderate-sized pyroclastic flows traveled 3 km NE down Tuitts Ghaut and White Bottom Ghaut, and a few smaller pyroclastic flows descended Tyers Ghaut to the N. Extensive ash clouds rose to an altitude of 6.1 km (20,000 ft) a.s.l. and drifted WNW, resulting in minor ashfall in inhabited areas. During 18-19 October, rockfalls and small pyroclastic flows continued to be detected.

Source: Montserrat Volcano Observatory (MVO)


7 October-13 October 2009

MVO reported that ash-venting events from Soufrière Hills lava dome, which had begun on 4 October, ceased in the early hours of 7 October; there were a total of thirteen events. The last three were associated with small pyroclastic flows that traveled about 500 m down Tyers Ghaut to the NNW. Observations on 7 October revealed tongues of rockfall and small pyroclastic-flow deposits at the heads of Tyers Ghaut to the NNW, Tar River valley to the E, White River to the S, and Gages to the W. A small area of incandescence from the N flank of the lava dome was seen during 7-8 October.

Source: Montserrat Volcano Observatory (MVO)


30 September-6 October 2009

MVO reported that a short volcano-tectonic earthquake swarm from Soufrière Hills lava dome was detected at 2100 on 4 October. A period of tremor and vigorous ash venting followed about an hour later. The resulting ash plume drifted WNW across the island and out to sea, causing ashfall in Old Towne and Olveston. The seismic signals indicated no explosive activity or pyroclastic flows, but only two rockfalls after the ash-venting event. During midnight to 0600 on 5 October, intermittent ash venting produced ash plumes that drifted WNW. Two more "ash venting" events occurred at 1035 and 1325, without precursory seismicity, producing ash plumes that rose to altitudes of 3-4.6 km (10,000-15,000 ft) a.s.l. Ash fell S of inhabited areas. Based on information from MVO and analyses of satellite imagery, the Washington VAAC reported that on 6 October several ash clouds rose to altitudes of 3.7-5.5 km (12,000-18,000 ft) a.s.l. and drifted W.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


24 June-30 June 2009

MVO reported that during 19-26 June activity from the Soufrière Hills lava dome was at a low level. On 20 June, a small pyroclastic flow that traveled E down the Tar River valley produced a small ash cloud that drifted W. The Hazard Level remained at 3.

Source: Montserrat Volcano Observatory (MVO)


27 May-2 June 2009

MVO reported that during 22-29 May activity from the Soufrière Hills lava dome was at a low level. On 23 May, a rockfall was detected by the seismic network and contained some low-frequency energy at the onset that may have indicated a small explosion. A small pyroclastic flow on 24 May traveled 1 km E towards the Tar River valley; a resultant ash plume drifted W over Gages Mountain and Plymouth. The Hazard Level remained at 3.

Source: Montserrat Volcano Observatory (MVO)


20 May-26 May 2009

MVO reported that during 15-22 May activity from the Soufrière Hills lava dome had increased slightly, but remained overall at a low level. Seismic activity increased slightly; tectonic earthquakes were noted on 16, 18, 20, and 21 May at depths less than 3 km beneath the lava dome. Lahars traveled down multiple river valleys on 18 May. Two possible explosions were detected on 21 May. The second and larger signal was followed by an ash plume that was seen drifting to the W over Gages Mountain. During 21-22 May, a strong smell of sulfur dioxide was noted from Salem (6 km NW) to Woodlands (1 km N of Salem).The Hazard Level remained at 3.

Source: Montserrat Volcano Observatory (MVO)


13 May-19 May 2009

MVO reported that during 8-15 May activity from the Soufrière Hills lava dome was generally at a low level. Multiple lahars traveled down several ravines during 12-15 May. Heavy rainfall caused erosion of the lava dome and pyroclastic flow deposits that were still hot; steam plumes occasionally laden with ash occurred periodically from the base of Tyre's ghaut and were visible from MVO. The Hazard Level remained at 3.

Source: Montserrat Volcano Observatory (MVO)


22 April-28 April 2009

MVO reported that during 17-24 April activity from the Soufrière Hills lava dome was at a low level. On 24 April, a small pyroclastic flow traveled E down the Tar River Valley. The Hazard Level remained at 3.

Source: Montserrat Volcano Observatory (MVO)


8 April-14 April 2009

MVO reported that during 3-10 April activity from the Soufrière Hills lava dome was at a low level. Heavy rainfall during 8-9 April caused lahars in multiple river valleys. The Hazard Level remained at 3.

Source: Montserrat Volcano Observatory (MVO)


1 April-7 April 2009

MVO reported that during 27 March-3 April activity from the Soufrière Hills lava dome was at a low level. On 1 April, a small pyroclastic flow traveled E down the Tar River Valley. The Hazard Level remained at 3. On 6 April, the Washington VAAC reported that an ash plume drifting at altitudes of 2.7-4.9 km (9,000-16,000 ft) a.s.l. was seen by a pilot flying from Antigua to Beef Island, 200-300 km NW. Ash was not seen on satellite imagery.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


18 March-24 March 2009

MVO reported that observations during an overflight of the Soufrière Hills lava dome on 18 March confirmed that a seismic signal recorded earlier that day was from a pyroclastic flow; the flow traveled E down the Tar River Valley, almost reaching the sea.

Source: Montserrat Volcano Observatory (MVO)


4 March-10 March 2009

MVO reported that during 27 February-6 March activity from the Soufrière Hills lava dome was at a low level. On 6 March, a pyroclastic flow traveled E down the Tar River Valley to the sea. The Hazard Level remained at 3.

Source: Montserrat Volcano Observatory (MVO)


25 February-3 March 2009

MVO reported that during 20-27 February activity from the Soufrière Hills lava dome was at a low level. On 24 February, a pyroclastic flow traveled E as far as the previous Tar River Valley coastline. The next day, a pyroclastic flow that traveled halfway down Tyre's Ghaut produced a small ash plume that drifted W. The Hazard Level remained at 3.

Source: Montserrat Volcano Observatory (MVO)


18 February-24 February 2009

MVO reported that during 13-20 February activity from the Soufrière Hills lava dome was at a low level. Four rockfalls were detected and seismicity had increased slightly compared to previous weeks. On 16 February, heavy rainfall triggered a small pyroclastic flow on the N side of the lava dome and a substantial lahar NW in the Belham River. A thermal camera showed a large amount of steaming in the Dyer's area (NW) during this period, and occasionally for a few days after. The Hazard Level was lowered to 3 on 19 February.

Source: Montserrat Volcano Observatory (MVO)


11 February-17 February 2009

MVO reported that during 6-13 February activity from the Soufrière Hills lava dome was at a low level. Two rockfalls were detected and seismicity was low. On 13 February, one small pyroclastic flow that originated in a gully on the N side of the lava dome traveled less than 1 km. The Hazard Level remained at 4.

Source: Montserrat Volcano Observatory (MVO)


4 February-10 February 2009

MVO reported that during 30 January-6 February activity from the Soufrière Hills lava dome increased slightly, although seismic activity was low. Three rockfalls were detected. On 5 February, one small pyroclastic flow that originated in a gully on the N side of the lava dome traveled less than 1 km and stopped in Tyre's Ghaut (NW). The Hazard Level remained at 4.

Source: Montserrat Volcano Observatory (MVO)


28 January-3 February 2009

MVO reported that during 23-30 January activity from the Soufrière Hills lava dome was at a low level; seismicity was low, rockfalls were minimal, and lava-dome incandescence at night was absent. The Hazard Level remained at 4.

Source: Montserrat Volcano Observatory (MVO)


21 January-27 January 2009

MVO reported that during 16-23 January activity from the Soufrière Hills lava dome was at a low level; seismicity was low, rockfalls were minimal, and lava-dome incandescence at night was absent. The Hazard Level remained at 4.

Source: Montserrat Volcano Observatory (MVO)


14 January-20 January 2009

MVO reported that during 9-16 January activity from the Soufrière Hills lava dome was at a low level; seismicity was low, rockfalls were minimal, and lava-dome incandescence at night was absent. The Hazard Level remained at 4.

Source: Montserrat Volcano Observatory (MVO)


7 January-13 January 2009

MVO reported that during 2-3 January activity from the Soufrière Hills lava dome increased drastically. On 2 January, an energetic pyroclastic flow and associated surge traveled down Tyers Ghaut (NW) and reached the upper part of Belham River. On 3 January, after a period of elevated seismicity, two explosions produced ash plumes to altitudes greater than 10.7 km (35,000 ft) a.s.l. Ashfall affected most of the island at elevations of 1.2 km (4,000 ft) a.s.l. and above. The explosions had significant "jet components" to at least 500 m above the dome. In-column collapses resulted in pyroclastic flows that traveled W and reached Plymouth (about 5 km W). After the second explosion, the level of activity decreased dramatically and remained low through 9 January. The Hazard Level remained at 4.

Source: Montserrat Volcano Observatory (MVO)


31 December-6 January 2009

MVO reported that during 26 December-2 January activity from Soufrière Hills lava dome was characterized by significantly increased lava extrusion, ash emissions, and pyroclastic flows. Lava extrusion on the top, N, W, and SW sides of the dome continued, and incandescence on the dome was visible at night when weather was favorable. Pyroclastic flows regularly reached the bottom of Tyers Ghaut (NW); surges associated with the larger flows spilled into the next valley to the W. Deposits filling Tyers Ghaut caused the flows to travel farther, into the upper part of the Belham River. Pyroclastic flows were also noted in valleys to the W. Ash emissions from the top of the lava dome increased; although most pyroclastic flows originated from rockfalls, some originated at the vent. Ashfall was reported in areas 6-7 km NW. Large incandescent blocks, deposited by rockfalls and pyroclastic flows, were visible on multiple occasions at night in the lower parts of Tyers Ghaut. Fires triggered by surges were visible in the neighboring valley. The Hazard Level remained at 4.

Based on analysis of satellite imagery and information from MVO, the Washington VAAC reported large eruptions on 3 January. Ash plumes drifted NE at an altitude of 7.6 km (25,000 ft) a.s.l., E at an altitude of 10.7 km (35,000 ft) a.s.l., S at an altitude of 6.1 km (20,000 ft) a.s.l., and W at an altitude of 2.4 km (8,000 ft) a.s.l. A thermal anomaly was detected. According to news articles, about 70 people were evacuated from Area B, about 6-8 km NW. The next day, steam-and-gas plumes possibly containing ash drifted W and WSW.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC), Antigua Sun


24 December-30 December 2008

MVO reported that during 19-26 December activity from Soufrière Hills lava dome was characterized by increased lava extrusion, rockfalls, and pyroclastic flows. Lava extrusion on the N, W, and SW sides of the dome continued and incandescence on the dome was visible at night when weather was favorable. Rockfall events increased by 80 percent compared to the previous week. Pyroclastic flows began to enter Tyers Ghaut (NW) on 20 December and likely reached the bottom of the ghaut (ravine) on 21, 23, and 25 December. On 22 December, the Hazard Level was increased to 4 due to the repeated occurrences of pyroclastic flows in the lower part of Tyers Ghaut. On 24 December, a large pyroclastic flow that reached Plymouth (about 5 km W), and possibly the sea, generated an ash plume to an altitude of 3 km (10,000 ft) a.s.l. Large incandescent blocks, deposited by rockfalls and pyroclastic flows, were visible on multiple occasions at night in the upper and middle parts of Tyers Ghaut.

Based on analysis of satellite imagery, the Washington VAAC reported that during 26-30 December ash plumes drifted W, WSW, SW, and S. Intermittent thermal anomalies were detected on satellite imagery on 27 December. Plumes rose to altitudes of 2.1-4.9 km (7,000-16,000 ft) a.s.l. on 28 and 30 December.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


17 December-23 December 2008

MVO reported that during 12-19 December activity from Soufrière Hills lava dome was characterized by increased lava extrusion, ash venting, rockfalls, and pyroclastic flows. Frequent pulses of ash rose from multiple places on the NW face of the lava dome and from a low on the dome behind Gages Mountain (as seen from Salem). On 13 December a pyroclastic flow traveled E down the Tar River Valley and reached the sea. Nighttime incandescence from the NW face was present during 16-19 December. Frequent rockfalls and several small pyroclastic flows descended Gages Valley. The largest pyroclastic flow, on 17 December, produced an ash cloud that rose to an altitude of 3 km (10,000 ft) a.s.l. On 18 December, observations of the lava dome confirmed significant growth on the SW flank. Photographs showed that most of the growth had taken place since 8 December; lava was filling in the area between the lava dome and Chance's Peak. Initial calculations suggested that the dome grew at a rate of 1 cubic meter per second during this time. Two small pyroclastic flows descended Galway's Valley on 19 December.

Based on analysis of satellite imagery and information from MVO, the Washington VAAC reported that during 19-23 December ash plumes drifted W, WSW, SW, and S. Thermal anomalies were detected on satellite imagery on 19 and 21 December. A pilot observed an ash plume at an altitude of 4.3 km (14,000 ft) a.s.l. on 20 December.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


10 December-16 December 2008

MVO reported that seismicity from Soufrière Hills lava dome remained elevated during 6-10 December. On 10 December, seven pyroclastic flows traveled W down Gages Valley, at least two reached Plymouth (about 5 km W). A few small pyroclastic flows were detected during 11-12 December. Monitoring data indicated that the volcano continued to inflate.

Based on analysis of satellite imagery and information from MVO, the Washington VAAC reported that on 14 December an ash plume drifted W at an altitude of 1.8 km (6,000 ft) a.s.l. A diffuse gas-and-steam plume possibly containing ash drifted W the next day. On 13 December, a pilot reported that an ash plume rose to altitudes of 4.6-5.2 km (15,000-17,000 ft) a.s.l. On 15 December, ash plumes at altitudes of 2.4-3 km (8,000-10,000 ft) a.s.l. drifted SW. The next day an ash plume drifted S and a thermal anomaly was detected on satellite imagery.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


3 December-9 December 2008

MVO reported a total of four explosive events from the Soufrière Hills lava dome during 2-5 December. The first event was triggered by a small dome collapse on 2 December, occurred without precursory seismicity, and was followed by a pyroclastic flow on the W flank. Resultant ash plumes, accompanied by lightning strikes, rose to an altitude of 12.2 km (40,000 ft) a.s.l. and drifted W. Explosions ejected incandescent blocks up to 1.6 km away from the dome that landed on Gages Mountain (about 1 km WNW), leaving impact craters. The pyroclastic flow also generated multiple pyroclastic surges that traveled S and N, setting fire to trees and bushes.

On 3 December another explosion scattered incandescent blocks all over the NW side of Gages Mountain. The third eruptive event, forceful emissions of ash on 4 December, resulted in ash plumes that rose to an altitude of 4.6 km (15,000 ft) a.s.l. The fourth explosive event occurred on 5 December and ejected incandescent blocks that were deposited on the NW side of Gages Mountain. A pyroclastic flow traveled to the W down Gages valley into Plymouth (about 5 km W) and an ash plume drifted NW.

On 3, 4, and 5 December small, relatively slow moving pyroclastic flows traveled no more than 3.2 km down the Gages valley. In periods between the events, near-continuous emissions of ash-laden steam were noted. The Hazard Level remained at 3.

According to the Washington VAAC, MVO reported eruptions on 6 December. Ash was seen on satellite imagery expanding in multiple directions, then to the E, SE, and W.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


26 November-2 December 2008

MVO reported that during 21-28 November the activity level at the Soufrière Hills lava dome remained low, and there was no evidence of lava extrusion. Rockfalls were detected by the seismic network. The lava dome continued to emit steam vigorously from multiple places, including new fumarolic areas on the W and S sides. Long-exposure photographs revealed several hot spots on the dome. The vertical cliff face on the W side of the dome was cracked in several places and erosion was evident at the base.

At approximately 2135 on 2 December, an explosion occurred on the W side of the lava dome without any precursory seismicity. Large blocks were ejected up to 1 km from the dome and incandescent blocks were scattered over the NW side of Gages Mountain (about 1 km WNW). A pyroclastic flow traveled to the W down Gages valley into Plymouth (about 5 km W), and further to the sea. Buildings in Plymouth caught fire and could be seen burning from Salem (about 4 km N of Plymouth) for several hours afterwards. Ash plumes were accompanied by lightning strikes and drifted W. The Hazard Level remained at 3.

Based on analysis of satellite imagery, the Washington VAAC reported that on 28 November a puff of ash and steam drifted SW and S.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


19 November-25 November 2008

MVO reported that during 14-21 November the activity level at the Soufrière Hills lava dome remained low, and there was no evidence of lava extrusion. Rockfalls were detected by the seismic network. Visual observations were hindered by clouds and vigorous steaming from the dome. Weak ash venting possibly occurred briefly during the reporting period, including on 20 November. The Hazard Level remained at 3.

Source: Montserrat Volcano Observatory (MVO)


12 November-18 November 2008

MVO reported that during 7-14 November the activity level at the Soufrière Hills lava dome increased slightly, but remained low, and there was no evidence of lava extrusion. Rockfalls were detected by the seismic network. Visual observations were hindered by clouds and vigorous steaming from the dome. Weak ash venting possibly occurred briefly on 13 November. The Hazard Level remained at 3.

Source: Montserrat Volcano Observatory (MVO)


5 November-11 November 2008

MVO reported that during 31 October-7 November the activity level at the Soufrière Hills lava dome was low and there was no evidence of lava extrusion. Photographs taken during an aerial inspection of the dome confirmed that the SE side was a very high (150-200 m) free-standing cliff not supported by talus. Erosion continued on the NE side and at the E and SE bases of the dome, further deepening the moat in the talus around the dome. The morphology of the top of the dome was complex and highly irregular with multiple steep lava protrusions separated by areas of lower elevation. Several spines and a bulbous shear lobe were visible. The Hazard Level remained at 3.

Source: Montserrat Volcano Observatory (MVO)


29 October-4 November 2008

MVO reported that during 24-31 October the activity level at the Soufrière Hills lava dome was low. There was no evidence of lava extrusion. On 26 October, observers aboard a fixed-wing aircraft confirmed that a few small pyroclastic flows traveled about 1.5 km down the Tar River Valley. Erosion down several V-shaped chutes continued at the E and SE bases of the dome further deepened the moat in the talus around the dome. Ongoing erosion of the talus pile on the W flank resulted in a well-incised network of gullies leading into the White River. On 27 October, a small pyroclastic flow seen from MVO traveled about 1 km down the Tar River Valley and generated a small ash plume that drifted over unpopulated areas to the W and SW, towards Plymouth. The Hazard Level remained at 3.

Source: Montserrat Volcano Observatory (MVO)


22 October-28 October 2008

MVO reported that during 17-24 October the activity level at the Soufrière Hills lava dome was slightly higher than the previous week and consisted mainly of volcanic seismicity. There was no evidence of lava extrusion. On the evening of 17 October several points of incandescence from locations previously glowing on 8 October were observed through binoculars. On 20 October three pyroclastic flows descended the Tar River Valley. They generated small ash plumes that drifted over unpopulated areas to the W and SW, towards Plymouth. The Hazard Level remained at 3.

Source: Montserrat Volcano Observatory (MVO)


15 October-21 October 2008

MVO reported that during 10-17 October, the activity level at the Soufrière Hills lava dome was low and consisted mainly of mudflows. Mudflows were particularly numerous during 15-16 October due to the passage of hurricane Omar to the N. Erosion of the talus slope on the E side of the lava dome also significantly increased and as a result, a large gap in the talus was created that exposed the core of the dome. During an overflight on 17 October, the lava dome was seen vigorous steaming and thermal imagery revealed that the hottest temperatures were associated with the new Gages vent formed in August. The Hazard Level remained at 3.

Based on analysis of satellite imagery and information from MVO, the Washington VAAC reported that on 20 October a pyroclastic flow or a rockfall generated a plume that drifted about 45 km W and was detaching from the island.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


8 October-14 October 2008

MVO reported that during 3-10 October, the activity level at the Soufrière Hills lava dome was slightly higher than the previous week and consisted mainly of rockfalls and mudflows. As a result of slow and continuous erosion of the lower part of the dome, rockfalls occurred on both the W side in the gully over Gages Wall and on the E side in the Tar River Valley. The rate of lava extrusion had declined significantly. Thermal imagery captured during an overflight on 8 October revealed that a major E-W oriented fracture in the dome, aligned with the Gages Valley and extending vertically over a few tens of meters, was associated with very elevated temperatures. Several other very hot areas were also detected. These areas were visible using binoculars from MVO later that night. The Hazard Level remained at 3.

Source: Montserrat Volcano Observatory (MVO)


1 October-7 October 2008

MVO reported that during 27 September-3 October, the W side of the Soufrière Hills lava dome continued to grow. Rockfalls were detected by the seismic network. The Hazard Level remained at 3.

Source: Montserrat Volcano Observatory (MVO)


24 September-30 September 2008

MVO reported that during 20-26 September, the W side of the Soufrière Hills lava dome continued to grow. Rockfalls were detected by the seismic network. The Hazard Level remained at 3.

Source: Montserrat Volcano Observatory (MVO)


17 September-23 September 2008

MVO reported that during 13-19 September, data suggested that the W side of the Soufrière Hills lava dome continued to grow. Rockfalls continued to descend the W side of the dome. The Hazard Level remained at 3.

Source: Montserrat Volcano Observatory (MVO)


10 September-16 September 2008

MVO reported that during 6-12 September, visual observations and other data suggested that the W side of the Soufrière Hills lava dome continued to grow. Rockfalls descended the W side of the dome and the smell of volcanic gases was occasionally noticed when the wind blew N and NE. The Hazard Level remained at 3.

Source: Montserrat Volcano Observatory (MVO)


3 September-9 September 2008

MVO reported that during 29 August-5 September, data suggested that the W side of the Soufrière Hills lava dome continued to grow. Lahars and rockfalls dominated the activity. Lahars likely descended the Tar River valley on 29 and 31 August. On 1 September, a lahar descended the Belham River valley to the NW; the event lasted approximately 50 minutes. A new vent on the NW part of the lava dome, a little further N of the previous Gages vent, was observed during an overflight on 4 September. The smell of volcanic gases was occasionally noticed when the wind blew N and NE. The Hazard Level remained at 3.

Source: Montserrat Volcano Observatory (MVO)


27 August-2 September 2008

MVO reported that during 22-29 August, observations suggested that the W side of the Soufrière Hills lava dome continued to grow. Lahars descended numerous river valleys during 25-27 August. Incandescence originating from a scar on lava dome created by the 28 July explosion, and then further expanded by a pyroclastic flow on 25 August, was observed on clear nights. Incandescence was also observed from an area N of the scar. Rockfalls descended the W side of the dome. The Hazard Level remained at 3.

Source: Montserrat Volcano Observatory (MVO)


20 August-26 August 2008

MVO reported that during 15-22 August, evidence suggested that the W side of the Soufrière Hills lava dome continued to grow. Cloud cover prevented visual observations. Rockfalls and long-period seismicity increased. Most of the rockfalls occurred on the W side of the lava dome in a new channel that developed below Gages Wall. Ash plumes occasionally generated by the rockfalls were most noticeable on 16 and 17 August. On 19 August a pyroclastic flow descended the Tar River Valley. According to news reports, on 25 August a rainfall-induced pyroclastic flow occurred on the W flank, split into two parts, and caused ashfall and a strong scent of gases in areas N. The event enlarged and steepened the rockfall gully below Gages Wall. The Hazard Level remained at 3.

Sources: Montserrat Volcano Observatory (MVO), Caribbean Net News


13 August-19 August 2008

MVO reported that new lava extrusion from Soufrière Hills started from the W side of the lava dome sometime between the 28 July lava-dome collapse event and 8 August, when a new channel of fresh rockfall material was seen below Gages Wall. Cloud cover often prevented visual observations. During 8-15 August, seismicity and the rate of lava extrusion were generally low and sulfur dioxide emissions were elevated. On 14 August the W side of the dome was visible and the explosion crater that was generated on 28 July was almost completely filled with new lava. Lava spilled over the lower and W side of the crater and generated rockfalls below Gages Wall that were observed and heard from St. George's Hill. During 14-15 August, the scent of volcanic gases was noticeable at times in inhabited areas of Montserrat. The Hazard Level was 3.

Source: Montserrat Volcano Observatory (MVO)


6 August-12 August 2008

MVO reported that seismic levels from Soufrière Hills were relatively low during 1-8 August. Sulfur dioxide emissions (tons per day) were significantly higher than emissions prior to the partial lava-dome collapse on 28 July. Unconfirmed reports indicated the presence of an ash plume on 3 August. A small ash cloud was seen on 7 August.

Further investigation of the 28 July event revealed that the total amount of material that collapsed from the dome was about 200,000-300,000 cubic meters. Satellite radar images indicated that the vent above Gages wall was enlarged by the explosion to about 150 x 60 meters, elongated E-W. Precautionary access restrictions for areas in and around Belham valley were lifted because evidence suggested that the dome had not been destabilized due to the event.

A new Hazard Level System, designed by MVO and Disaster Management Coordination Agency (DMCA) in consultation with the Government of Montserrat and community groups, was implemented on 8 August. The system divides the southern two-thirds of the island into six zones, and includes two Maritime Exclusion Zones. The Hazard Level ranges from 1-5 and is set by the National Disaster Preparedness, Response, and Advisory Committee (NDPRAC) with advice from MVO. The Hazard Level restricts access into each of the zones depending on the number assigned and is unrelated to the Alert Level. The current Hazard Level was 3.

Source: Montserrat Volcano Observatory (MVO)


23 July-29 July 2008

MVO reported no evidence of lava-dome growth at Soufrière Hills during 18-26 July. At least six eruptive events occurred during 20-22 July, each producing ash plumes that rose to altitudes of 2 km (6,000 ft) a.s.l. or lower. The ash plumes drifted W; ashfall was reported in Old Towne. Rumbling noises were heard in nearby areas and lightning strikes were observed. Small pyroclastic flows during 20-21 July traveled E down the Tar River valley with the largest one reaching within 500 m of the ocean. The Alert Level remained elevated at 4 (on a scale of 0-5).

On 26 July, seismicity increased significantly and then decreased. Seismicity increased again at approximately 0100 on 27 July and continued at a high level until about 0935 when a short series of eruptive events started. The first and largest ash-venting event of this series produced an ash plume that rose to an altitude of 2.5 km (8,000 ft) a.s.l. and drifted W and NW. Ashfall was reported in Plymouth and St George's Hill. Two events that followed produced ash plumes to an altitude of 1.5 km (5,000 ft) a.s.l.

A partial lava-dome collapse began at 1127 on 28 July without any precursory activity. Part of the dome's W flank collapsed and generated pyroclastic flows that reached Plymouth and the sea. A few explosions during the collapse produced ash plumes; the largest ash plume rose to an altitude of 12 km (40,000 ft) a.s.l.

Source: Montserrat Volcano Observatory (MVO)


16 July-22 July 2008

MVO reported no evidence of lava-dome growth at Soufrière Hills during 11-18 July. Seismic activity remained low. The E talus slope continued to erode, producing minor rockfalls that descended into the Tar River Valley. Following a small swarm of volcano-tectonic earthquakes on 20 July, four eruptive events each produced ash plumes that rose to altitudes of 2 km (6,000 ft) a.s.l. and drifted W. The first two events generated plumes above the Tar River Valley possibly from small pyroclastic flows. Ashfall was reported in Old Towne. Rumbling noises were heard in nearby areas and lightning strikes were observed. The Alert Level remained elevated at 4 (on a scale of 0-5).

Source: Montserrat Volcano Observatory (MVO)


2 July-8 July 2008

MVO reported no evidence of lava-dome growth at Soufrière Hills during 28 June-4 July. Seismic activity remained low. The E talus slope continued to erode, producing minor rockfalls that descended into the Tar River Valley. The Alert Level remained elevated at 4 (on a scale of 0-5).

Source: Montserrat Volcano Observatory (MVO)


25 June-1 July 2008

MVO reported no evidence of lava-dome growth at Soufrière Hills during 21-27 June. Seismic activity remained low. Heavy rainfall resulted in minor mudflows down the Belham River. The E talus slope continued to erode, producing minor rockfalls that descended into the Tar River Valley. The Alert Level remained elevated at 4 (on a scale of 0-5).

Source: Montserrat Volcano Observatory (MVO)


18 June-24 June 2008

MVO reported no evidence of lava-dome growth at Soufrière Hills during 14-20 June. Seismic activity remained low. On 19 June, mild ash venting from the Gages vent (to the W) resulted in an ash plume that rose to an altitude less than 1.2 km (4,000 ft) a.s.l. and drifted E. The E talus slope continued to erode, producing minor rockfalls that descended into the Tar River Valley. The Alert Level remained elevated at 4 (on a scale of 0-5).

Source: Montserrat Volcano Observatory (MVO)


11 June-17 June 2008

MVO reported no evidence of lava-dome growth at Soufrière Hills during 7-13 June. Seismic activity remained low. The E talus slope continued to erode, producing minor rockfalls that descended into the Tar River Valley. The Alert Level remained elevated at 4 (on a scale of 0-5).

Source: Montserrat Volcano Observatory (MVO)


4 June-10 June 2008

MVO reported no evidence of lava-dome growth at Soufrière Hills during 31 May-6 June. Seismic activity remained low. The Alert Level remained elevated at 4 (on a scale of 0-5).

Source: Montserrat Volcano Observatory (MVO)


28 May-3 June 2008

MVO reported that an explosion at Soufrière Hills on 29 May produced an ash plume to an altitude of 3 km (10,000 ft) a.s.l. which drifted SW and generated a pyroclastic flow. The explosion had no precursory seismicity and was heard in multiple areas to the NW. The pyroclastic flow descended a few hundred meters to the W. Observations during an overflight the following day suggested that the explosion and pyroclastic flow originated from the Gages vent.

Source: Montserrat Volcano Observatory (MVO)


21 May-27 May 2008

MVO reported that activity at Soufrière Hills decreased slightly during 17-23 May. On 23 May, several pulses of ash venting from Gages vent to the W produced ash plumes to an altitude of approximately 1.8 km (5,900 ft) a.s.l. and drifted E.

Based on pilot reports, information from MVO, and observations of satellite imagery, the Washington VAAC reported that during 23-27 May steam plumes with small amounts of ash or possible ash rose to altitudes of 1.2-1.4 km (4,000-4,500 ft) a.s.l. and drifted W and NW.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


14 May-20 May 2008

MVO reported that activity at Soufrière Hills increased during 9-19 May. The seismic network recorded 17 rockfalls. An eruptive event on 13 May produced an ash plume to an altitude of 3 km (10,000 ft) a.s.l. and was accompanied by a single long-period earthquake. A blue sulfur dioxide plume was also noted. Ash emissions from two areas in the Gages vent to the W were observed on 15 May, but may have started on 14 May. The resultant ash plume rose about 200 m above the lava dome and drifted W. A small rockfall was noted and gentle roaring noises were reported. A new fumarolic area was seen on the SE side of Chances Peak. Ash emissions from Gages vent continued on 16 May. The Alert Level remained elevated at 4 (on a scale of 0-5).

Based on information from MVO and observations of satellite imagery, the Washington VAAC reported that steam plumes with small amounts of ash continued during 17-19 May and drifted N and WNW.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


7 May-13 May 2008

MVO reported that during 2-9 May the lava dome at Soufrière Hills changed very little, based on measurable parameters. A small pyroclastic flow descended the E flank on 5 May. Light ashfall was reported in the Old Town area about 9 km NW. Ash deposits were also evident in the Corkhill (NW) and St. Georges Hill (N) areas. Heavy rainfall generated lahars. The Alert Level remained elevated at 4 (on a scale of 0-5).

Based on information from MVO and observations of satellite imagery, the Washington VAAC reported that an ash plume rose to an altitude of 3 km (10,000 ft) a.s.l. and drifted NW on 13 May.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


30 April-6 May 2008

MVO reported that during 25 April-2 May the level of volcano-tectonic earthquakes at Soufrière Hills increased and was the highest since February 2006. Degassing from a vent above Gages Wall was audible in the St. George's Hill area to the NW. Steaming from the area above Tyre's Ghaut to the NW was visible. The Alert Level remained elevated at 4 (on a scale of 0-5).

Source: Montserrat Volcano Observatory (MVO)


16 April-22 April 2008

MVO reported that during 4-18 April the lava dome at Soufrière Hills changed very little, based on measurable parameters. Overflights on 9 and 16 April revealed that the E side of the lava dome continued to erode and exposed more resistant solid material below. A small pyroclastic flow traveled 500 m down the E flank on 10 April and generated a small ash plume that quickly dissipated to the W. Two more pyroclastic flows were observed on 16 April. The larger flow traveled 1 km down the E flank and was followed by relatively strong degassing. The Alert Level remained elevated at 4 (on a scale of 0-5).

Source: Montserrat Volcano Observatory (MVO)


2 April-8 April 2008

MVO reported that during 1-4 April the lava dome at Soufrière Hills changed very little, based on measurable parameters. Seismic activity was very low and one rockfall signal was recorded. The Alert Level remained elevated at 4 (on a scale of 0-5).

Source: Montserrat Volcano Observatory (MVO)


26 March-1 April 2008

MVO reported that during 25-31 March the lava dome at Soufrière Hills changed very little, based on visual observations and other measurable parameters. Fumarolic activity was concentrated on the NW and SE flanks, and at the head of Gages Valley to the W where the emissions were bluish. The Alert Level remained elevated at 4 (on a scale of 0-5).

Source: Montserrat Volcano Observatory (MVO)


19 March-25 March 2008

MVO reported that that during 19-25 March the lava dome at Soufrière Hills changed very little, based on visual observations and other measurable parameters. Fumarolic activity was concentrated on the NW and SE flanks where abundant sulfur deposits were noted, and at the head of Gages Valley to the W. The Alert Level remained elevated at 4 (on a scale of 0-5).

Source: Montserrat Volcano Observatory (MVO)


12 March-18 March 2008

MVO reported that that during 11-18 March the lava dome at Soufrière Hills changed very little, based on visual observations on 12 March and other measurable parameters. The E side of the lava dome continued to erode, with material accumulating in the Tar River Valley. Fumarolic activity was concentrated on the NW and SE flanks and at the head of Gages Valley to the W. The Alert Level remained elevated at 4 (on a scale of 0-5).

Source: Montserrat Volcano Observatory (MVO)


5 March-11 March 2008

MVO reported that that during 4-11 March the lava dome at Soufrière Hills changed very little, based on visual observations during an overflight on 6 March. The E talus slope continued to erode, with both fresh and older material accumulating in the Tar River Valley. Fumaroles around the lava dome were active, but less vigorous W in the Gages Wall area on 7 March. The Alert Level remained elevated at 4 (on a scale of 0-5).

Source: Montserrat Volcano Observatory (MVO)


27 February-4 March 2008

MVO reported that that during 27 February-4 March the lava dome at Soufrière Hills changed very little, based on limited visual observations during an overflight on 29 February and from ground locations. The E talus slope continued to erode, with both fresh and older material accumulating in the Tar River Valley. Active fumaroles around the lava dome were observed during breaks in cloud cover. The Alert Level remained elevated at 4 (on a scale of 0-5).

Source: Montserrat Volcano Observatory (MVO)


20 February-26 February 2008

MVO reported that that during 20-26 February the lava dome at Soufrière Hills changed very little, based on limited visual observations during an over flight on 21 February and from ground locations. The E talus slope continued to erode, with both fresh and older material accumulating in the Tar River Valley. Active fumaroles around the lava dome were observed during the overflight. Seismic activity was very low and low-level rockfall activity continued. The Alert Level remained elevated at 4 (on a scale of 0-5).

Source: Montserrat Volcano Observatory (MVO)


13 February-19 February 2008

MVO reported that that during 13-19 February the lava dome at Soufrière Hills changed very little, based on visual observations. Seismic activity was very low and low-level rockfall activity continued. Fumarolic activity on the N and E flanks continued. Active fumaroles were also noted in the Galway's area to the S of the dome. Clouds obscured views to the W in the Gages Wall area. Heavy rainfall triggered lahars in multiple drainages. On 13 February, the lower Belham river valley to the W was impassable for a short time due to lahars. The Alert Level remained elevated at 4 (on a scale of 0-5).

Source: Montserrat Volcano Observatory (MVO)


6 February-12 February 2008

MVO reported that that during 5-12 February the lava dome at Soufrière Hills changed very little, based on limited observations (due to inclement weather) during overflights. Seismic activity was very low and low-level rockfall activity continued. Fumarolic activity on the N and E flanks continued. Active fumaroles were also noted in the Galway's area to the S of the dome. Clouds obscured views to the W in the Gages Wall area. The Alert Level remained elevated at 4 (on a scale of 0-5).

Source: Montserrat Volcano Observatory (MVO)


30 January-5 February 2008

MVO reported that that during 30 January-5 February the lava dome at Soufrière Hills changed very little, based on visual observations during an over flight on 30 January and from multiple locations. Seismic activity was very low and low-level rockfall activity continued. Fumarolic activity on the N and E flanks continued. Active fumaroles were also noted in the Galway's area to the S of the dome and W in the Gages Wall area. The Alert Level remained elevated at 4 (on a scale of 0-5).

Source: Montserrat Volcano Observatory (MVO)


23 January-29 January 2008

MVO reported that the lava dome at Soufrière Hills changed very little, based on visual observations during an over flight on 23 January. Visual observations were limited during 22-28 January. Seismic activity was very low and low-level rockfall activity continued. Fumarolic activity on the N and E flanks continued. Active fumaroles were also noted in the Galway's area to the S of the dome and W in the Gages Wall area. The Alert Level remained elevated at 4 (on a scale of 0-5).

Source: Montserrat Volcano Observatory (MVO)


16 January-22 January 2008

MVO reported that the lava dome at Soufrière Hills had changed very little, based on visual observations during an over flight on 23 January. Visual observations were limited during 22-29 January. Seismic activity was very low and low-level rockfall activity continued. Fumarolic activity on the N and E flanks also continued, along with active fumaroles in the Galway's area to the S of the dome and W in the Gages Wall area. The Alert Level remained elevated at 4 (on a scale of 0-5).

Source: Montserrat Volcano Observatory (MVO)


9 January-15 January 2008

MVO reported that fumarolic activity on the N and E flanks of the Soufrière Hills lava dome continued during 28 December-15 January. Active fumaroles were also noted in the Galway's area to the S of the dome and W in the Gages Wall area. Occasional rockfalls occurred; one produced a small ash plume on 7 January. Observations during an overflight on 9 January confirmed that the lava dome morphology had not changed since 3 January. The Alert Level remained elevated at 4 (on a scale of 0-5).

Based on pilot reports, information from MVO, and observations of satellite imagery, the Washington VAAC reported that a steam-and-gas plume with light ash content drifted S and SW on 10 January.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


2 January-8 January 2008

MVO reported that fumarolic activity on the N and E flanks of the Soufrière Hills lava dome continued during 28 December-8 January. Active fumaroles were also noted in the Galway's area to the S of the dome and W in the Gages Wall area. Occasional rockfalls were restricted to the Tar River valley. Observations during an overflight on 3 January confirmed that the lava dome morphology had not changed since the previous reporting period. The Alert Level remained elevated at 4 (on a scale of 0-5).

Source: Montserrat Volcano Observatory (MVO)


26 December-1 January 2008

MVO reported that during 24-28 December the lava dome at Soufrière Hills changed very little, based on visual observations. Seismic activity was very low and low-level rockfall activity occurred in the Tar River valley. Fumarolic activity on the N and E flanks of the dome and W in the Gages Wall area continued. The Alert Level remained elevated at 4 (on a scale of 0-5).

Source: Montserrat Volcano Observatory (MVO)


19 December-25 December 2007

MVO reported that during 17-24 December the lava dome at Soufrière Hills changed very little, based on visual observations. Seismic activity was very low and low-level rockfall activity continued. Fumarolic activity on the N and E flanks of the dome continued. The Alert Level remained elevated at 4 (on a scale of 0-5).

Source: Montserrat Volcano Observatory (MVO)


12 December-18 December 2007

MVO reported that during 7-17 December the lava dome at Soufrière Hills changed very little, based on visual observations. Seismic activity was very low and low-level rockfall activity continued. Fumarolic activity on the N and E flanks of the dome continued. The Alert Level remained elevated at 4 (on a scale of 0-5).

Source: Montserrat Volcano Observatory (MVO)


5 December-11 December 2007

MVO reported that during 3-7 December the lava dome at Soufrière Hills changed very little, based on visual observations. Seismic activity was very low and low-level rockfall activity continued. Fumarolic activity on the N and E flanks of the dome continued. The Alert Level remained elevated at 4 (on a scale of 0-5).

Source: Montserrat Volcano Observatory (MVO)


28 November-4 December 2007

MVO reported that during 23 November-3 December the lava dome at Soufrière Hills changed very little, based on visual observations. Seismic activity was very low and low-level rockfall and pyroclastic flow activity continued. Fumarolic activity on the N and E flanks of the dome were observed. On 29 November, a regional M 7.4 earthquake occurred at 1500. A few minutes later, a small pyroclastic flow traveled down the E flank. At 1530, three more pyroclastic flows traveled E down the Tar River Valley. The Alert Level remained elevated at 4 (on a scale of 0-5).

Source: Montserrat Volcano Observatory (MVO)


31 October-6 November 2007

MVO reported that during 31 October-5 November the lava dome at Soufrière Hills changed very little, based on limited visual observations due to cloud cover. Seismic activity was very low and low-level rockfall and pyroclastic flow activity continued. The Alert Level remained elevated at 4 (on a scale of 0-5).

Source: Montserrat Volcano Observatory (MVO)


24 October-30 October 2007

MVO reported that during 24-30 October the lava dome at Soufrière Hills changed very little, based on visual observations. Seismic activity was very low and low-level rockfall and pyroclastic flow activity continued. During 25-26 October, vigorous lahar activity was noted, especially to the E, including the Tar River valley. Ashfall was subsequently visible over much of N Montserrat, possibly due to rockfall activity and steam venting. On 30 October a small pyroclastic flow was observed in the Tar River valley. The Alert Level remained elevated at 4 (on a scale of 0-5).

Source: Montserrat Volcano Observatory (MVO)


17 October-23 October 2007

MVO reported that during 17-23 October the lava dome at Soufrière Hills changed very little, based on visual observations. Seismic activity was very low and low-level rockfall activity continued. On 12 October, a small pyroclastic flow descended about 2 km E down the Tar River valley. A resultant ash plume drifted W. On 23 October, lahars descended down drainages on all sides of the volcano. The Alert Level remained elevated at 4 (on a scale of 0-5).

Source: Montserrat Volcano Observatory (MVO)


10 October-16 October 2007

MVO reported that during 10-16 October the lava dome at Soufrière Hills changed very little, based on visual observations. Seismic activity was very low and low-level rockfall activity continued. The Alert Level remained elevated at 4 (on a scale of 0-5).

Source: Montserrat Volcano Observatory (MVO)


3 October-9 October 2007

MVO reported that during 3-9 October the lava dome at Soufrière Hills changed very little, based on visual observations. Seismic activity was very low and low-level rockfall activity continued. On 3 October, lahars were noted in several drainages, including the Belham river valley to the NW. Steam venting was noted in the upper parts of Belham Valley and in Tyres Ghaut to the NW. The Alert Level remained elevated at 4 (on a scale of 0-5).

Source: Montserrat Volcano Observatory (MVO)


26 September-2 October 2007

MVO reported that during 26 September-2 October the lava dome at Soufrière Hills changed very little, based on visual observations. Seismic activity was very low and low-level rockfall activity continued. On 26 September, lahars were noted in several drainages, including the Belham river valley to the NW. The Alert Level remained elevated at 4 (on a scale of 0-5).

Source: Montserrat Volcano Observatory (MVO)


19 September-25 September 2007

MVO reported that during 19-25 September the lava dome at Soufrière Hills changed very little, based on visual observations. Seismic activity was very low and low-level rockfall activity continued. The Alert Level remained elevated at 4 (on a scale of 0-5).

Source: Montserrat Volcano Observatory (MVO)


12 September-18 September 2007

MVO reported that during 11-18 September the lava dome at Soufrière Hills changed very little, based on visual observations. Seismic activity was very low and low-level rockfall activity continued. Based on satellite imagery, the Washington VAAC reported that an ash plume drifted SW on 16 September. On 17 September, a lahar traveled down the Belham river valley to the NW. The Alert Level remained elevated at 4 (on a scale of 0-5).

Source: Montserrat Volcano Observatory (MVO)


5 September-11 September 2007

MVO reported that during 3-11 September the lava dome at Soufrière Hills changed very little, based on visual observations. Seismic activity was very low and low-level rockfall activity continued. The Alert Level remained elevated at 4 (on a scale of 0-5).

Source: Montserrat Volcano Observatory (MVO)


29 August-4 September 2007

MVO reported that during 28 August-3 September the lava dome at Soufrière Hills changed very little, based on visual observations. Seismic activity was very low and low-level rockfall activity continued. The Alert Level remained elevated at 4 (on a scale of 0-5).

Source: Montserrat Volcano Observatory (MVO)


22 August-28 August 2007

MVO reported that during 21-28 August the lava dome at Soufrière Hills changed very little, based on visual observations. Seismic activity was very low and low-level rockfall activity continued. On 23 August, heavy rainfall triggered small rockfalls and four pyroclastic flows to the E down the Tar River Valley. Ash and steam emissions from the dome produced a plume that drifted W. A lahar occurred in the Belham river valley to the NW. The Alert Level remained elevated at 4 (on a scale of 0-5).

Source: Montserrat Volcano Observatory (MVO)


15 August-21 August 2007

MVO reported that during 13-21 August the lava dome at Soufrière Hills changed very little, based on visual observations. Seismic activity was very low and low-level rockfall activity continued. The Alert Level remained elevated at 4 (on a scale of 0-5).

Source: Montserrat Volcano Observatory (MVO)


8 August-14 August 2007

MVO reported that during 3-13 August the lava dome at Soufrière Hills changed very little, based on visual observations. Seismic activity was very low and low-level rockfall activity continued. On 10 August, lahars were detected in all drainages due to heavy rainfall. The Alert Level remained elevated at 4 (on a scale of 0-5).

Source: Montserrat Volcano Observatory (MVO)


1 August-7 August 2007

MVO reported that during 27 July-3 August, the lava dome at Soufrière Hills changed very little, based on visual observations. Seismic activity was very low and low-level rockfall activity affected all sides of the dome. On 30 July, three pyroclastic flows traveled about 1.5 km down the N side of the Tar River Valley. The Alert Level remained elevated at 4 (on a scale of 0-5).

Source: Montserrat Volcano Observatory (MVO)


25 July-31 July 2007

MVO reported that based on visual observations, the lava dome at Soufrière Hills changed very little during 25-26 July. Seismic activity was very low and low-level rockfall activity continued. The Alert Level remained elevated at 4 (on a scale of 0-5).

Source: Montserrat Volcano Observatory (MVO)


18 July-24 July 2007

MVO reported that during 13-24 July, the lava dome at Soufrière Hills changed very little, based on visual observations. Seismic activity was very low and low-level rockfall activity continued. Heavy rainfall generated lahars in E drainages on 19 July. The Alert Level remained elevated at 4 (on a scale of 0-5).

Source: Montserrat Volcano Observatory (MVO)


11 July-17 July 2007

MVO reported that during 6-13 July the lava dome at Soufrière Hills changed very little based on visual observations, and seismic activity was very low. Low-level rockfall activity continued. The Alert Level remained elevated at 4 (on a scale of 0-5).

Source: Montserrat Volcano Observatory (MVO)


4 July-10 July 2007

MVO reported that during 29 June-10 July the lava dome at Soufrière Hills changed very little based on visual observations, and seismic activity was very low. Low-level rockfall activity continued, however, and predominantly affected the Tar River Valley to the E. Heavy rainfall generated lahars in E drainages during 4-6 July. The Alert Level remained at 4 (on a scale of 0-5).

Source: Montserrat Volcano Observatory (MVO)


27 June-3 July 2007

MVO reported that during 22-29 June the lava dome at Soufrière Hills changed very little based on visual observations, and seismic activity was very low. Low-level rockfall and pyroclastic flow activity continued, however, and predominantly affected the Tar River Valley to the E. The volume of the dome was an estimated 208 million cubic meters. The Alert Level remained at 4 (on a scale of 0-5).

Source: Montserrat Volcano Observatory (MVO)


20 June-26 June 2007

MVO reported that during 20-25 June the lava dome at Soufrière Hills changed very little based on visual observations, and seismic activity was very low. Low-level rockfall and pyroclastic flow activity continued, however, and predominantly affected the Tar River Valley to the E. The Alert Level remained at 4 (on a scale of 0-5).

Source: Montserrat Volcano Observatory (MVO)


13 June-19 June 2007

MVO reported that during 8-18 June the lava dome at Soufrière Hills changed very little based on visual observations, and seismic activity was very low. Low-level rockfall and pyroclastic flow activity continued. The Alert Level remained at 4 (on a scale of 0-5).

Source: Montserrat Volcano Observatory (MVO)


6 June-12 June 2007

MVO reported that during 1-12 June the lava dome at Soufrière Hills changed very little based on visual observations from a helicopter and seismic activity was very low. Low-level rockfall and pyroclastic flow activity continued during 1-12 June. On 8 June, a small pyroclastic flow was observed in the upper parts of Farrell's Plain to the N. Fresh pyroclastic deposits were also observed to the E in the Tar River Valley and on the S side of the lava dome. On 11 June, heavy rains generated lahars in all drainages. Two pyroclastic flows occurred. The Washington VAAC reported that on 11 June, an ash plume was visible on satellite imagery drifting NW. The plume may have reached an altitude of 3.7 km (12,000 ft) a.s.l. The Alert Level remained at 4 (on a scale of 0-5).

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


30 May-5 June 2007

MVO reported that during 25 May-1 June the lava dome at Soufrière Hills changed very little based on visual observations and seismic activity was very low. Low-level rockfall and pyroclastic flow activity continued. On 31 May, pyroclastic flows traveled approximately 1 km E in the Tar River Valley. The Alert Level remained at 4 (on a scale of 0-5).

Source: Montserrat Volcano Observatory (MVO)


23 May-29 May 2007

Based on visual observations, MVO reported that during 18-25 May lava-dome growth at Soufrière Hills likely ceased and the overall structure of the dome changed very little. Seismic activity was very low. The Alert Level remained at 4 (on a scale of 0-5).

Source: Montserrat Volcano Observatory (MVO)


16 May-22 May 2007

Based on visual observations, MVO reported that during 11-21 May lava-dome growth at Soufrière Hills likely ceased and the overall structure of the dome changed very little. Low-level rockfall and pyroclastic flow activity continued. Seismic activity was very low. The Alert Level remained at 4 (on a scale of 0-5).

Source: Montserrat Volcano Observatory (MVO)


9 May-15 May 2007

Based on visual observations, MVO reported that during 4-11 May lava-dome growth at Soufrière Hills likely ceased and the overall structure of the dome changed very little. Rockfall activity continued. The Alert Level remained at 4 (on a scale of 0-5).

Source: Montserrat Volcano Observatory (MVO)


25 April-1 May 2007

During 25 April-1 May, lava-dome growth at Soufrière Hills continued at a reduced rate. Rockfalls and pyroclastic flows occasionally occurred. On 30 April, two pyroclastic flows were observed to the NE in Tuitt's Ghaut.

Source: Montserrat Volcano Observatory (MVO)


18 April-24 April 2007

During 13-20 April, visual observations suggested that lava-dome growth at Soufrière Hills continued at a reduced rate. Material originating from the lava dome's growing E-facing shear lobe was shed down the Tar River Valley. Heavy rains resulted in lahars in several drainages 16-17 April. During 18-20 April, a gas plume drifted N and NE and a bluish haze containing sulfur dioxide was observed flowing down the N flanks due to light winds coming from the S.

Source: Montserrat Volcano Observatory (MVO)


11 April-17 April 2007

Based on visual observations, lava-dome growth at Soufrière Hills continued at a reduced rate during 6-13 April. Material originating from the E-facing shear lobe was shed down the Tar River Valley. Minor rockfalls and pyroclastic flows were noted. On 17 April, a small pyroclastic flow was observed to the NW in the upper part of Tyres Ghaut. The lava-dome volume was an estimated 208 million cubic meters.

Source: Montserrat Volcano Observatory (MVO)


4 April-10 April 2007

During 30 March-9 April, lava-dome growth at Soufrière Hills remained reduced or had possibly ceased. Small, intermittent pyroclastic flows originating from the E-facing shear lobe occurred in the Tar River Valley. Fumarolic activity was observed around the SE and NW regions of a collapse scar at the head of Tyres Ghaut, and to the W, above Gages Valley. Incandescent rockfalls from the E side of the dome were seen at night during 5-9 April.

Source: Montserrat Volcano Observatory (MVO)


28 March-3 April 2007

During 23 March-3 April, lava-dome growth at Soufrière Hills was reduced or possibly paused. Small, intermittent pyroclastic flows occurred in the Tar River Valley. Fumarolic activity was observed around the region of a collapse scar at the head of Tyres Ghaut and was audible during 28-29 March. The Washington VAAC reported that a SW-drifting, diffuse plume and a hotspot were visible on satellite imagery on 2 April.

Source: Montserrat Volcano Observatory (MVO)


21 March-27 March 2007

During 16-26 March, lava-dome growth at Soufrière Hills continued and was concentrated on the NE side. Pyroclastic flows mainly affected the sector from the ENE to the NW of the dome and traveled intermittently E down the Tar River Valley. Small flows (<500 m in length) occurred NW in Tyres Ghaut, and one flow was observed at the top of Farrell's Plain. On 18 March, steam venting following heavy rains was observed NW on Cork Hill.

Source: Montserrat Volcano Observatory (MVO)


14 March-20 March 2007

During 9-16 March, lava-dome growth at Soufrière Hills continued and was concentrated on the NE side. Intermittent pyroclastic flows, possibly originating from the large blocky spine on the edge of the E lobe, traveled E down the Tar River Valley and produced large ash plumes. One of the plumes on 12 March rose to an altitude of 3 km (10,000 ft) a.s.l. and drifted NW. On 13 March, a steam-rich plume rose to 2.4 km (8,000 ft) a.s.l. and drifted W. By 14 March, the spine was completely shed. On 15 March, heavy rains caused mudflow activity in several drainages. Pyroclastic flows were observed NW in Tyre's Ghaut and ashfall was reported from the Salem /Old Towne areas. On 16 March, pyroclastic flows were observed in Tyre's Ghaut and in the Tar River Valley. A resultant ash plume drifted WNW. Based on satellite imagery, the Washington VAAC reported that diffuse ash plumes drifted NW during 17-18 March.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


7 March-13 March 2007

During 2-9 March, lava-dome growth at Soufrière Hills continued and was concentrated on an E-facing lobe topped with blocky, spine-like protrusions. Rockfalls affected the E and NE flanks. Pyroclastic flows traveled 2 km and were confined E in the Tar River Valley. Heightened pyroclastic activity on 7 March resulted in an ash plume that rose to an estimated 2.4 km (8,000 ft) a.s.l. and drifted W. On 11 March, a pyroclastic flow traveled down the NE flank into White's Ghaut. On 12 March, a large, blocky spine leaned steeply towards the NE.

Based on satellite imagery, San Juan Weather Forecast Agency (WFO), and pilot reports, the Washington VAAC reported light ash and haze over several Caribbean islands during 7-10 March. Based on news articles, the presence of ash and dust from the Sahara Desert prompted some airlines in Puerto Rico to delay and cancel flights on 10 March.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC), Associated Press


28 February-6 March 2007

During 28 February-2 March, lava-dome growth at Soufrière Hills continued and was concentrated on the E and N sides. Ash venting and roaring noises originated from the W side of the dome, above Gages Wall. On 2 March, two small pyroclastic flows traveled down Tyres Ghaut to the NW.

Based on satellite data and pilot reports the Washington VAAC reported continuous ash emissions during 28 February-4 March. Resultant plumes rose to altitudes of 2.1 km (7,000 ft) a.s.l. and drifted mainly W. A thermal anomaly was detected in the crater on satellite imagery. On 6 March, an ash plume rose to altitudes between 1.8-2.7 km (6,000-9,000 ft) a.s.l. and drifted W and NW.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


21 February-27 February 2007

During 16-23 February, lava-dome growth at Soufrière Hills continued and was concentrated on the E and N sides. Small pyroclastic flows traveled down the Tar River Valley to the E, Gages to the W, and Tyres Ghaut to the NW. Ash venting and roaring noises originated from an area above Gages to the SW, where a new blocky lobe was visible. Moderately-sized pyroclastic flows traveled E down the Tar River Valley during 24-25 and 27 February. Bright incandescence at the dome was observed during the reporting period.

Based on satellite data, pilot reports, and information from the MVO, the Washington VAAC reported continuous ash emissions during 21-27 February. Resultant plumes rose to altitudes of 2.1-6.1 km (7,000-20,000 ft) a.s.l. and drifted mainly NE, NW, and W. A thermal anomaly was detected in the crater on satellite imagery.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


14 February-20 February 2007

During 9-16 February, seismic activity at Soufrière Hills was slightly elevated as compared to previous weeks. The lava-dome volume was estimated at 200 million cubic meters based on recent measurements from LIDAR data. Previous measurements over-estimated the lava-dome volume due to the perceived location of the dome and the lack of data from inside the crater. The height of the dome was about 1060 m a.s.l. During 17-18 February, rockfalls and small pyroclastic flows traveled W down Gages Valley and E down Tar River Valley. Incandescence was seen from the E and N sides of the dome. Rockfalls continued on 19 and 20 February.

Based on satellite data and information from the MVO, the Washington VAAC reported continuous emissions during 14-20 February. Resultant plumes rose to altitudes of km (5,000-8,000 ft) a.s.l. and drifted mainly NW, W, and S. A thermal anomaly in the crater was detected on satellite imagery.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


7 February-13 February 2007

During 7-13 February, growth of the Soufrière Hills lava dome continued on the W side. A small lobe was observed on 7 February growing to the SW. On 8 February, three pyroclastic flows traveled a maximum distance of a few kilometers E down the Tar River Valley. At least one of the pyroclastic flows was the result of a small collapse from the S or SW part of the dome. Small pyroclastic flows traveled NW down Tyres Ghaut on 9 February and down the northern flanks onto Farrell's Plain on 12 and 13 February. Based on satellite imagery, information from MVO, and pilot reports, the Washington VAAC reported that ash-and-gas and steam plumes drifted predominantly NW during 10-13 February. Plumes reached a maximum altitude of 2.7 km (9,000 ft) a.s.l. on 13 February

Based on a news article on 13 February, the lava-dome volume was approximately 250 million cubic meters, surpassing the previous record size of 240 million cubic meters in 2003.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC), Caribbean Net News


5 February-11 February 2007

During 27 April-8 May, visual observations suggested that lava-dome growth at Soufrière Hills continued at a reduced rate or ceased. Fresh deposits were evident at the head of Tyres Ghaut to the NW, the upper parts of Farrell's Plain and Tuitt's Ghaut to the N, and the upper parts of the Tar River Valley to the E. Pyroclastic activity was ongoing on the E and NE sides of the dome during 27 April-4 May and pyroclastic flows were observed in the Tar River Valley and on Farrell's plain, into Tuitt's Ghaut.

Source: Montserrat Volcano Observatory (MVO)


31 January-6 February 2007

Based on satellite imagery, the MVO, and pilot reports, the Washington VAAC reported that a diffuse plume from Soufrière Hills rose to an altitude of 1.5 km (5,000 ft) a.s.l. and drifted WNW on 31 January. Measurable activity was low and visual observations were limited due to cloud cover. On 6 January, a photograph taken from a helicopter showed that the dome had continued to grow towards the W side of the crater.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


24 January-30 January 2007

During 24-30 January, measurable activity at Soufrière Hills remained low. Based on satellite imagery, information from MVO, and a pilot report, the Washington VAAC reported that ash plumes were visible during 26-27 January. The plumes were likely a result of rockfall activity. On 28 January, a large pyroclastic flow traveled down the Tar River Valley and reached the sea.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


17 January-23 January 2007

During 17-23 January, measurable activity at Soufrière Hills was low and visual observations were limited due to cloud cover. Gas and ash venting that originated from the W side of the dome continued throughout the reporting period. A clear view on 22 January revealed that the collapse scar from the 8 January event was filled in. The NW sector vigorously degassed and a small spine was noted on the W side. On 23 January, a large pyroclastic flow traveled W down Gages Valley.

Source: Montserrat Volcano Observatory (MVO)


10 January-16 January 2007

During 10-16 January, lava-dome growth at Soufrière Hills continued and was focused on the entire NW quadrant of the dome. During 10-11 January, one pyroclastic flow was observed to the W in Gages Valley and one to the NW in Tyres Ghaut. On 15 January, a relatively large pyroclastic flow traveled S down the Tar River Valley and produced a cloud that drifted W. Gas and ash venting originated from the W side of the dome and seismicity remained at very low levels.

Source: Montserrat Volcano Observatory (MVO)


3 January-9 January 2007

Activity including rapid lava-dome growth, pyroclastic flows, and ash venting increased at Soufrière Hills during 3-9 January. Dome growth was concentrated in the NW quadrant which was the highest part of the dome. Pyroclastic flows, originating from the NW, were observed in Tyres Ghaut (NW), Gages Valley (W), and N, behind Gages Mountain and accompanied by ash venting. On 4 January, a notable event resulted in simultaneous pyroclastic flows in Tyres Ghaut and Gages Valley, and a resultant ash cloud reached an altitude of 2.5 km (8,200 ft) a.s.l. The maximum distance for the Gages Valley flow was 4 km. During 6-7 January, distances of pyroclastic flows increased in Tyres Ghaut and possibly exceeded 1.5 km.

Activity including rapid lava-dome growth, pyroclastic flows, and ash venting increased at Soufrière Hills during 3-9 January. Dome growth was concentrated in the NW quadrant which was the highest part of the dome. Pyroclastic flows, originating from the NW, were observed in Tyres Ghaut (NW), Gages Valley (W), and N, behind Gages Mountain and accompanied by ash venting. On 4 January, a notable event resulted in simultaneous pyroclastic flows in Tyres Ghaut and Gages Valley, and a resultant ash cloud reached an altitude of 2.5 km (8,200 ft) a.s.l. The maximum distance for the Gages Valley flow was 4 km. During 6-7 January, distances of pyroclastic flows increased in Tyres Ghaut and possibly exceeded 1.5 km.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


27 December-2 January 2007

During 22-29 December, the rate of lava-dome growth at Soufrière Hills increased and was focused on the W, where gas-and-ash venting occurred. A high whaleback lobe directed towards the SW was observed on 26 December. On 28 December, a small pyroclastic flow traveled W toward Gages valley. The Washington VAAC reported on-going steam and ash emissions that were visible on satellite imagery during 27 December-2 January.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


20 December-26 December 2006

During 15-22 December, moderate lava-dome growth at Soufrière Hills continued and was focused on the SW part of the dome. Rockfalls and pyroclastic flows occurred on the S side of the dome and in the upper parts of both White's and Tuitt's Ghauts. Based on satellite imagery and pilot reports, the Washington VAAC reported that steam emissions with variable amounts of ash drifted W on 23 and 24 December. A pilot reported that an ash plume rose to an altitude of 3 km (10,000 ft) a.s.l. and drifted W on 24 December. The MVO reported that the emissions originated from a vent on the W side of the dome. A small pyroclastic flow was visible NW in the upper reaches of Tyre's Ghaut and venting became more energetic. The alert level was raised to 4 (on a scale of 0-5). At night, incandescent rockfalls were visible from the NW and W.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


13 December-19 December 2006

During 8-15 December, moderate lava-dome growth at Soufrière Hills continued and was focused on the SW part of the dome. Most of the dome surface in a sector from the S to the NW was below 100°C based on thermal images and moisture along with sulfur deposits accumulated along the SE edge. The dome overtopped the NE crater wall and fresh rock and boulder deposits were observed in that region.

Source: Montserrat Volcano Observatory (MVO)


6 December-12 December 2006

During 1-8 December, the MVO reported that observations of Soufrière Hills were limited due to cloud cover. On 2 December, the lava dome was visible and growth was concentrated on the NE. Based on information from the MVO, satellite imagery, and pilot reports, the Washington VAAC reported a small explosion on 8 December. The resulting ash plume rose to an altitude of 2.4 km (8,000 ft) a.s.l. and drifted W.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


29 November-5 December 2006

During 24 November-1 December, lava-dome growth at Soufrière Hills continued and was concentrated on the NE part of the edifice. The two cracks in the curved back of the shear E-facing lobe on the summit have propagated downward and divided the lobe into three blocks. Rockfalls and small pyroclastic flows traveled down the sector between the SE and NE flanks and are also affecting the N part of the dome at the back of the lobe. Pyroclastic flows reached the upper region of Tuitts Ghaut on 27 November.

Source: Montserrat Volcano Observatory (MVO)


22 November-28 November 2006

During 17-24 November, lava-dome growth at Soufrière Hills continued and was concentrated on the NE part of the edifice. Ash venting originated from the westernmost of two cracks in the curved back of the shear E-facing lobe on the summit. Rockfalls and small pyroclastic flows traveled down the SW and NE flanks. Pyroclastic flows reached both the upper region of Tuitts Ghaut (N) and the sea via the Tar River Valley (E) on 23 November. An explosion produced an ash plume that rose to altitudes of 1.5-1.7 km (4,900-5,600 ft) a.s.l.

Source: Montserrat Volcano Observatory (MVO)


8 November-14 November 2006

During 3-10 November, lava-dome growth at Soufrière Hills continued and was concentrated on the E part of the edifice. Rockfalls and small pyroclastic flows originating from a large active lobe on the NE sector of the dome traveled down the SW and NE flanks. High-temperature rockfalls from the NNE sector were deposited on a ridge between Tuitt's and White's Ghauts. Sulfur dioxide measurements were higher than previous weeks, but still within the long-term average range.

Based on information from the MVO, satellite imagery, and pilot reports, the Washington VAAC reported continuous ash-and-gas emissions during 8-14 November. Resulting plumes drifted mainly W and S. A hotspot was detected on satellite imagery during 9-13 November.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


1 November-7 November 2006

During 27 October-3 November, lava-dome growth at Soufrière Hills continued and was concentrated on the E and NE part of the edifice. Rockfalls and small pyroclastic flows originating from the active lobe traveled down the NE flank. Aerial observation confirmed the existence of a large, shear, E-facing lobe on the NE side of the dome. Ash-and-steam venting continued.

Based on information from the MVO, satellite imagery, and the Piarco MWO, the Washington VAAC reported that ash and gas emissions during 1-6 November produced mainly diffuse plumes that drifted NW, W, and SW. Plumes reached altitudes of 2.7 km (9,000 ft) a.s.l. on 3 November. A hotspot was detected on satellite imagery on 3 and 5 November.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


25 October-31 October 2006

During 20-27 October, lava-dome growth at Soufrière Hills continued and was concentrated on the NE part of the edifice. Rockfalls and small pyroclastic flows originating from the active lobe traveled down the NE flank. Several small stubby spine-like structures were observed on the SE summit region of the dome.

Based on information from the MVO, satellite imagery, and the Piarco MWO, the Washington VAAC reported that continuous ash and gas emissions during 25-31 October produced plumes that drifted NW and W. Plumes reached altitudes of 2.1 km (7,000 ft) a.s.l. A hotspot was detected on satellite imagery during 25-27 October and 29 October.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


18 October-24 October 2006

During 13-20 October, lava-dome growth at Soufrière Hills continued and was concentrated on the NE part of the edifice. A new E-facing shear lobe with a smooth, curved back enlarged during the reporting period. Rockfalls and small pyroclastic flows originating from the active lobe affected the NE flank. On a few occasions, pyroclastic flows from the N flank spilled over Farrel's wall (the crater rim). The vent above Gage's wall was less active compared to the previous reporting period. A vent S of the active lobe periodically produced both ash and gas. Ash fell in northern areas of the island. Heavy rainfall resulted in mudflow activity in all drainage systems.

Based on information from the MVO, pilot reports, and the Piarco MWO, the Washington VAAC reported that continuous ash and gas emissions on 18, 20, and 22-23 October produced plumes that drifted W, NW, and NE. Plumes reached altitudes of 2.7 km (9,000 ft) a.s.l. A hotspot was detected on satellite imagery.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


11 October-17 October 2006

During 6-13 October, lava-dome growth at Soufrière Hills continued and was concentrated on the NE part of the edifice. The vents just inside Gage's wall and on the summit of the dome periodically produced both ash and gas. Heavy rainfall on 9 and 11-12 October resulted in mudflow activity in all drainage systems. Ash fell in the N part of the island.

Based on information from the MVO, pilot reports, and the Piarco MWO, the Washington VAAC reported that continuous ash and gas emissions during 10-17 October produced plumes that drifted NW, N, and NE. Plumes reached altitudes of 2.1-4.6 km (7,000-15,000 ft) a.s.l. A minor pyroclastic flow on 16 October produced an ash plume that drifted NNE. A hotspot was detected on satellite imagery from 12 to 17 October.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


4 October-10 October 2006

MVO reported that during 29 September-6 October the lava dome at Soufrière Hills continued to grow at a moderate rate. Rockfalls were concentrated on the N and NE sectors. The vents just inside Gage's wall and on the summit of the dome periodically produced both ash and gases. The lava-dome volume was estimated at 90 million cubic meters.

Based on information from the MVO, pilot reports, and the Piarco MWO, the Washington VAAC reported ongoing emissions during 5-10 October. Plumes reached altitudes of 2.4 km (8,000 ft) a.s.l. and drifted W.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


27 September-3 October 2006

Visual observations of Soufrière Hills during 22-29 September showed that the dome continued to grow at a moderate rate. Growth appeared to have occurred predominantly on the domes summit area, and on its eastern side, with a prominent lobe growing in this location. The vents just inside Gage's wall and on the summit of the dome periodically produced both ash and gases. There were also a number of pyroclastic flows during the period, some of which appear to have had explosive onsets in the seismic record. Northerly winds during 28 and 29 September resulted in minor ashfall in inhabited areas. The sulfur dioxide flux for the reporting period averaged around 450 tonnes/day, varying between 850 tonnes/day on 22 September and 190 tonnes/day on 26 September. Aviation ash advisories on 2-3 October described continuous ash emissions reaching 2.4 km (8,000 ft) a.s.l. that eventually extended 140 km W.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


20 September-26 September 2006

MVO reported that during 15-22 September the lava dome at Soufrière Hills continued to grow at a moderate rate, slower than earlier in the month. Growth appears to have occurred predominantly in the summit area and on the S and E sides of the dome. The vent situated in the Gages Wall is still active, with minor explosive activity seen during an observation flight on 19 September. An intense 30-minute episode of volcanic tremor on 19 September was accompanied by rockfall activity that caused minor pyroclastic flows down the N and NE flanks of the lava dome. On 22 September the volume of the dome was about 80 million cubic meters. Seismicity was dominated by rockfalls with a significant drop in earthquake activity relative to the previous reporting period. The alert level was reduced to 3 (on a scale of 0-5) on 21 September. Aviation ash advisories during this period noted continuous ash emissions.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


13 September-19 September 2006

MVO reported that during 8-15 September, the lava dome at Soufrière Hills continued to grow at a high rate. On 9 and 10 September, ash venting from the Gages wall was vigorous and accompanied by small explosions producing black jets up to 100 m above the vent. Pyroclastic flows from fountain collapse occurred on all sides of the dome and notably reached 1 km W down Gages valley. On 11 September, the collapse of an over-hanging lava lobe produced pyroclastic flows NE down the Tar River valley. On 13 September, one pyroclastic flow in the same area reached the sea. On 14 September, vigorous ash venting resumed.

Based on information from the MVO, pilot reports, and the Piarco MWO, the Washington VAAC reported that continuous ash and gas emissions during 13-19 September produced plumes that reached altitudes of 2.4-3.7 km (8,000-12,000 ft) a.s.l. and drifted predominantly NW, W, and SW. A hotspot was visible on satellite imagery.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


6 September-12 September 2006

During 6-12 September, lava-dome growth at Soufrière Hills was substantial and concentrated on the W part of the edifice. A vent that had opened above Gage's Wall on 31 August vigorously emitted plumes of hot gases. A second vent near the summit of the dome emitted ash-and-steam plumes.

Based on information from the MVO, pilot reports, and the Piarco MWO, the Washington VAAC reported that ash, gas, and steam emissions on 6 and 7 September produced diffuse plumes that drifted WNW. On 10, 11, and 12 September, ash-and-gas plumes reached altitudes of 3 km (10,000 ft) a.s.l. and drifted E and SW. A hotspot was detected on satellite imagery on 6, 7, and 10-12 September.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


30 August-5 September 2006

Based on satellite imagery and reports from the MVO, the Washington VAAC reported that the Soufrière Hills lava dome collapsed at 1740 on 29 August. Ash venting was seen on satellite imagery prior to the collapse at 0615 and 1245. The plumes reached altitudes of 2.4 km (8,000 ft) a.s.l., drifted N, and then shifted to the W and SW. According to the Antigua Aircraft Tower, the dome collapse produced a plume that rose to an altitude of about 9 km (30,000 ft) a.s.l. The upper portion of the cloud drifted E and the lower portion possibly drifted N and W. Pyroclastic flows reached the sea down the Tar River Valley.

On 30 August, small pyroclastic flows were visible on the NE and S flanks of the lava dome. On 31 August, two vigorous ash-and-steam vents opened on the W and N flanks accompanied by tremor. A pilot reported an ash plume at an altitude of 4.6 km (15,000 ft) a.s.l. drifting W. The Alert Level was raised to 4 (on a scale of 0-5). The Washington VAAC reported continuous gas and ash emissions during 1-4 September; plumes reached altitudes of 3 km (10,000 ft) a.s.l. and drifted W.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


23 August-29 August 2006

During 18-25 August, the Soufrière Hills lava dome continued to grow. A marked increase of long-period and hybrid earthquakes was noted from 18 to 20 August. Based on satellite imagery and reports from the MVO, the Washington VAAC reported that continuous emissions of ash and steam produced plumes that reached altitudes of 1.5 km (5,000 ft) a.s.l. on 28 August.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


16 August-22 August 2006

Lava dome growth continued at Soufrière Hills during 11-18 August. The activity was concentrated in the N half of the dome. Based on information from the MVO, pilot reports, and the Piarco MWO, the Washington VAAC reported continuous ash emissions on 18 and 19 August. The plumes reached altitudes of 2.4 km (8,000 ft) a.s.l. and drifted W.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


9 August-15 August 2006

During 4-11 August, the Soufrière Hills lava dome continued to grow. The sulfur-dioxide flux averaged 230 metric tons per day. The Alert Level remained at 3 (on a scale of 0-5).

Source: Montserrat Volcano Observatory (MVO)


2 August-8 August 2006

During 29 July-4 August, the Soufrière Hills lava dome continued to grow, mainly to the E. The loss of prominent spines made the dome appear more symmetrical. On 2 August, a small pyroclastic flow occurred and was associated with light ash fall to the N of the island. The Alert Level remained at 3 (on a scale of 0-5).

Source: Montserrat Volcano Observatory (MVO)


26 July-1 August 2006

Lava dome growth continued at Soufrière Hills during 21-28 July. On 27 July, the blocky spine first observed on 21 July was seen leaning to the E, and many new spines had formed along the S-N-trending crest of the lava dome. Seismic activity decreased during the reporting period. On 30 July, a thermal anomaly was visible on satellite imagery.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


19 July-25 July 2006

During 14-21 July, the Soufrière Hills lava dome grew noticeably. A blocky spine was observed on the NE side, where growth had been focused. On 18 July, the spine height was estimated at 895 m. The Alert Level remained at 3 (on a scale of 0-5).

Source: Montserrat Volcano Observatory (MVO)


12 July-18 July 2006

According to the Washington VAAC, the Montserrat Volcano Observatory reported a pyroclastic flow from Soufrière Hills on 13 July that reached the sea and produced an ash plume to an altitude of 2.4 km (8,000 ft) a.s.l.

Source: Washington Volcanic Ash Advisory Center (VAAC)


5 July-11 July 2006

The Montserrat Volcano Observatory estimated that the Soufrière Hills lava dome volume was 27 million cubic meters on 27 June, prior to the 30 June partial lava-dome collapse, which means the growth rate during the month of June averaged about 8 cubic meters per second. On 7 July, the Alert Level was lowered to 3 (on a scale of 0-5).

Source: Montserrat Volcano Observatory (MVO)


28 June-4 July 2006

Due to increased seismic activity at Soufrière Hills during approximately 24-29 June, the Alert Level was raised to 4 (on a scale of 0-5). On 30 June around 1300, the lava dome partially collapsed and produced pyroclastic flows to the E. According to the Washington VAAC, a pilot reported that an ash plume reached an altitude of 3 km (10,000 ft) a.s.l. and drifted NW. The VAAC also reported that the Montserrat Volcano Observatory indicated a second dome collapse occurred at 1830 on 30 June that also generated ash plumes to altitudes of 3 km (10,000 ft) a.s.l.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC), Associated Press, Antigua Sun, Radio Jamaica


21 June-27 June 2006

During 16-23 June, only brief observations of the Soufrière Hills lava dome were possible due to inclement weather. The lava dome filled the base of the crater, which suggested a high rate of growth. On 17 June, lahars reached the Belham and other valleys on the lower flanks. Wet ash accumulated NW in the Salem and Olveston areas.

Source: Montserrat Volcano Observatory (MVO)


14 June-20 June 2006

During 9-16 June, the Soufrière Hills lava dome continued to grow, but at a slower rate than during the 2-9 June reporting period. Vigorous ash-and-gas venting occurred from a vent to the N of the lava dome.

Source: Montserrat Volcano Observatory (MVO)


7 June-13 June 2006

During 2-9 June, the Soufrière Hills lava dome continued to grow at a high rate of 10 cubic meters per second on average (average growth rate during January-April was 6 cubic meters per second). Vigorous ash-and-gas venting occurred from a vent to the W of the lava dome. According to a pilot report and MVO, the Washington VAAC reported on 9 June that a steam plume with little ash content reached an altitude of 1.5 km (5,000 ft) a.s.l. Weak incandescence was observed on satellite imagery on 10 June.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


31 May-6 June 2006

During 26 May to 2 June, the Soufrière Hills lava dome continued to grow at a high rate of 10 cubic meters per second (average growth rate during January-April was 6 cubic meters per second). Numerous rockfalls and vigorous ash venting occurred from a vent to the W of the lava dome. A pilot reported that a small ash plume extended NW on 31 May. Ash plumes extending W and NW were visible on satellite imagery during 1-5 June and reached a maximum altitude of 2.7 km (9,000 ft) a.s.l. on 3 and 5 June. An ash plume on 4 June extended N of Puerto Rico.

According to the Washington VAAC, ash-plume emissions continued during 24-30 May. On 24 May, emission of small volumes of gas and thin ash plumes continued and drifted W and SW. A pilot near St. Croix (NW) reported that the ash/haze layer reached an altitude of 1.5 km (5,000 ft) a.s.l. Ashfall was reported at San Juan (NW) airport. During 25-30 May, ash plumes reached an altitude of 4.6 km (15,000 ft) a.s.l. and drifted W and NW. On 24-26 May, a hot spot was visible on infrared satellite imagery.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


24 May-30 May 2006

During 24-30 May, lava-dome growth continued at Soufrière Hills. On 23 May, the new lava dome was observed for the first time since the 20 May dome collapse. The new lava dome was darker than the previous lava dome and on 25 May, reached a height of 767 m. Rockfalls were observed on the NE and SW sectors of the new lava dome. The largest of several active vents were on the W side of the dome and were responsible for ash-venting episodes.

According to the Washington VAAC, ash-plume emissions continued during 24-30 May. On 24 May, emission of small volumes of gas and thin ash plumes continued and drifted W and SW. A pilot near St. Croix (NW) reported that the ash/haze layer reached an altitude of 1.5 km (5,000 ft) a.s.l. Ashfall was reported at San Juan (NW) airport. During 25-30 May, ash plumes reached an altitude of 4.6 km (15,000 ft) a.s.l. and drifted W and NW. On 24-26 May, a hot spot was visible on infrared satellite imagery.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


17 May-23 May 2006

MVO reported that on the morning of 20 May a major lava-dome collapse at Soufriére Hills occurred over a time period of less than three hours. Approximately 90 million cubic meters of the lava dome material was shed from the summit leaving a broad, deep, eastward-sloping crater. Pyroclastic flows traveled E down the Tar River Valley and were estimated to extend out to 3 km over the sea. Lahars due to excessive rain were produced NW in the Belham River Valley, N in the Trants area, and to the NE. An ash cloud reached 16.8 km (55,000 ft) a.s.l. by 0740, the highest reported ash cloud during the 10 years of the eruption, and traveled NW. Lithics (average size of 3.5 cm across) fell NW of the volcano. On 21 May, ash and mud fell on the northern parts of the island. Prior to the lava-dome collapse, during 12 May and 19 May, lava extrusion had continued.

The Washington VAAC reported that the ash plume from the 20 May dome collapse initiated at approximately 0700. On 21 May, the remnant ash cloud from 20 May was at a height of ~11.3 km (37,000 ft) a.s.l. along the northern coast of South America and the Southern Caribbean. An ash cloud at a height of ~7 km (23,000 ft) a.s.l. extended S of Puerto Rico and the Dominican Republic. According to news reports, the ash cloud on 20 May forced the suspension of some international flights in areas of the Caribbean through 21 May. On 22 May, multi-spectral imagery indicated that an ash plume at a height of ~3 km (10,000 ft) a.s.l. extended over the islands of Anguilla, St. Martin, and St. Kitts. On 23 May, a thin ash plume was visible on satellite imagery and moved WNW.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC), Associated Press


10 May-16 May 2006

During 5-12 May, the new lobe of the lava dome at Soufrière Hills that developed towards the S produced rockfalls that predominantly extended from the W to the SE. On the 12th, the lava dome volume was approximately 80 million cubic meters, having grown at an average rate of 8 cubic meters per second through April. Seismicity typical of this current growth phase was dominated by rockfall activity during the report period. The average sulfur-dioxide flux during the week was 702 metric tons per day.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


26 April-2 May 2006

Observations of Soufrière Hills during 21-28 April revealed that lava extrusion continued. Dome growth occurred over a sector extending SW to NE. The eastward facing lobe continued to grow on the NE side of the dome and a central spine was observed on 28 April. Small rockfalls and pyroclastic flows continued to initiate from the active E flank of the dome, adding to the talus in the upper reaches of the Tar River Valley. Rockfalls were accompanied by minor ash venting. Thermal images taken on 27 April indicated some very hot (in excess of 400 degrees centigrade) areas on the E flank of the dome. During the report period seismicity was dominated by rockfalls, as has been the case throughout the on-going phase of dome growth. The sulfur-dioxide flux averaged 520 metric tons per day, close to the long-term average for the entire eruption.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


19 April-25 April 2006

Observations of Soufrière Hills' lava dome during 14-21 April suggested that lava extrusion continued. Growth occurred over a sector extending E to N, and on 18 April observers noted a smooth area of the dome resembling a whale's back. Numerous small rockfalls continued from the active eastern flanks of the lava dome, adding to the talus in the upper reaches of the Tar River Valley. Rockfalls were accompanied by minor ash venting. Due to unusual wind conditions, plumes were predominately transported N and NW, shifting to the E on 20 April. As a result of this process, light ashfall occurred over much of Montserrat.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


12 April-18 April 2006

Observations of the lava dome at Soufrière Hills suggested that lava extrusion continued during 7-14 April. Growth occurred over a sector extending E to N, and an eastward-facing lobe developed on the NE side of the dome. Numerous small rockfalls continued from the active eastern flanks of the dome, adding to the talus in the upper reaches of the Tar River valley. Rockfalls were accompanied by minor ash venting. Due to the wind coming from the S in contrast to the normal prevailing wind direction (from the E) during the second half of the report period, ash fell over many parts of Montserrat: notably after a minor pyroclastic flow occurred at 0645 on 14 April. During the report period, the sulfur-dioxide flux averaged 540 metric tons per day. The hydrogen chloride to sulfur dioxide ratio on 12 April was 3.75, higher than 2.64 measured the previous week.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


5 April-11 April 2006

Low extrusion rates occurred at Soufrière Hills' lava dome at the beginning of the interval 31 March to 7 April. Continued lava-dome growth was focused E, with a lava lobe growing in that direction and the majority of rockfalls and pyroclastic flows occurring in the SE to NE sector. Photographs taken on 6 April clearly showed slightly elevated extrusion rates with lobe development on the E side of the dome. One moderate-sized pyroclastic flow occurred around 1030 on 2 April, resulting in minor ashfall to the W of the island. During the report period, the sulfur-dioxide flux averaged 578 metric tons per day. The hydrogen chloride to sulfur dioxide ratio was 2.3 and 2.6 on 4 and 5 April, respectively.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


29 March-4 April 2006

During 24-31 March, lava-dome growth at Soufrière Hills was focused towards the E, with a lava lobe growing in that direction and the majority of rockfalls and pyroclastic flows occurring in the SE and NE sectors of the volcano. The largest pyroclastic flows traveled as far as 2 km NE down Tar River Valley. The sulfur-dioxide flux averaged 523 metric tons per day.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


22 March-28 March 2006

Observations of Soufrière Hills during 17-24 March revealed that lava-dome growth was focused in the summit area and towards the E and NE. The N side of the lava dome showed little change. Rockfalls and pyroclastic flows were restricted to the Tar River Valley and they were particularly numerous on 19-20 March. The largest pyroclastic flows traveled as far as 2 km down Tar River Valley. There was an increase in gas emission during the report period. The sulfur-dioxide flux averaged 1,034 metric tons per day, with high gas emissions occurring on days of elevated pyroclastic-flow activity. The hydrogen chloride to sulfur dioxide ratio was 2.8 on 22 March. The ground-deformation network continued to indicate deflation across the volcano.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


15 March-21 March 2006

Cloudy conditions during 10-17 March limited visual observations of Soufrière Hills, however, lava-dome growth continued to be focused towards the E, NE, and NW as was evidenced by the production of large numbers of rockfalls and small pyroclastic flows. The ground deformation network showed a continuing trend of line shortening across the volcano. The sulfur-dioxide flux averaged 480 metric tons per day. The hydrogen chloride to sulphur dioxide ratio ranged between 1.1. and 2.1.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


8 March-14 March 2006

During 3-10 March, lava-dome growth continued at Soufrière Hills in a northerly direction and the dome reached a height of ~950 m. The active lava lobe shed rockfalls and small pyroclastic flows to the W, N, and E. A very vigorous gas vent was seen on the W side of the lava dome on 8 March, above Gages valley. Small fumaroles were visible at the top of Gages valley and below the lava dome remnant that stands at the top of Gages Valley. The shortening monitored by Electronic Distance Measurement (EDM) on the NE flank of the volcano between Jack Boy Hill and Hermitage Estate since mid-February appeared to have eased. Recently processed Global Positioning System (GPS) baseline data suggested continued deflation, with the distance between Mongo Hill and South Soufrière Hill (N/S baseline) reducing, and E/W baselines remaining largely unchanged. The sulfur-dioxide flux varied greatly, but produced an overall average of 454 metric tons per day for the week.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


1 March-7 March 2006

On 26 February, rapid vertical growth of the lava dome at Soufrière Hills was visible on camera images, and by 27 February a large spine about 30 m wide and at least 30 m high had developed at the dome's summit. By 28 February this spine had split into two parts and was leaning precariously to the NE. At about 2115 on 28 February the overhanging parts of the spine disintegrated and generated pyroclastic flows that travelled down the Tar River Valley almost as far as the coast. A low-level ash cloud drifted W. There were further changes to the shape of the spines and the upper NE flank of the volcano in the following days as they disintegrated further. Rockfalls were visible on the N, NE, and E flanks of the volcano. Some fumaroles were observed on the upper outside part of Gages Wall (W of the lava dome) on 27 February suggesting movement of fluids in this area.

The sulfur-dioxide flux was low, with an average of 388 metric tons measured daily. Electronic Distance Measurement surveys showed a shortening of the distance between Jack Boy Hill and Hermitage on the NE flank of the volcano of 6 mm since 10 February. Similarly, the distance between Windy Hill and a reflector on Farrell's on the N flank of the volcano shortened by 6 mm in the same period. The last significant detected change in these measurements was in response to the onset of lava-dome growth in August 2005.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


22 February-28 February 2006

Photographs of Soufrière Hills taken during 17-24 February confirmed ongoing lava-dome growth. The newest lobe, which appeared on the dome's NW side on 10 February, continued to grow on all sides. It appeared to have filled in the gap between the lava dome and the N and W crater walls. It also grew significantly to the E, overtopping the older lobe by the end of the report period. After 22 February, incandescent rockfalls were visible at night, coursing down the N,E, and SW sides of the dome and into the Tar River Valley. The sulfur-dioxide flux was low, with an average of 286 metric tons per day.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


15 February-21 February 2006

MVO reported that during vigorous ash-and-steam venting at Soufrière Hills on 10 February, a small dark lobe of lava was observed on the western side of the lava dome in the crater. By early on 11 February this lobe had advanced rapidly towards the NE side of the dome and was visible as a steep-sided plateau of lava from inhabited areas around Salem. Photographs from fixed cameras showed continued changes to this lava lobe over the next few days, and the NE margin could be seen glowing at night and shedding rockfalls into the NE part of the crater. The initial growth rate of this lobe was well over 5 cubic meters per second, but the rate declined around 17 February. The new lava lobe began to fill the gap between the lava dome and the northern and western crater walls, raising the possibility that small rockfalls could spill over those areas in coming weeks.

The sulfur-dioxide flux averaged 568 metric tons per day. Data from Fourier Transform Infra Red spectrometry measurements indicated an increase in the hydrogen chloride/sulfur dioxide mass ratio in the gas plume from 2.0 in the last reporting period to an average of 2.5 on 13 February.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


8 February-14 February 2006

MVO reported to the Washington VAAC that increased activity began at Soufrière Hills on 10 February. That day, satellite imagery showed a prominent hotspot at the volcano and a NW-drifting ash plume at a height of ~3 km (10,000 ft) a.s.l. Ash-and-gas emissions continued through 15 February, producing plumes to a height of ~2.7 km (9,000 ft) a.s.l. MVO reported that on 15 February, there was markedly less volcanic activity, with steam and a small amount of ash emitted to ~1.4 km (4,450 ft) a.s.l.

Source: Washington Volcanic Ash Advisory Center (VAAC)


1 February-7 February 2006

Volcanic and seismic activity at Soufrière Hills were at elevated levels during 27 January to 3 February. Images taken by a remote camera at the beginning of the report period indicated that the lava dome continued to grow over a broad sector extending from the SW around to the NE. A pair of spines was observed on the SE side of the dome on 29 January, although both these and the fin-like structures (relatively thin, vertical planar spines) on the SE flank of the dome collapsed during the report period. Numerous small rockfalls were observed emanating from the S,E, and NE flanks of the lava dome, adding to the talus in the upper reaches of the Tar River Valley. Continued lava-dome growth was observed, particularly at the southern end, which was higher than the northern end of the dome. The sulfur-dioxide flux averaged 594 metric tons per day.

Source: Montserrat Volcano Observatory (MVO)


25 January-31 January 2006

Activity at Soufrière Hills remained elevated during 20-27 January. Images taken by a remote camera showed that the lava dome continued to grow over a broad sector extending from the SW around to the NE. On 22 January, two new fin-like structures (relatively thin, vertical planar spines) were seen on the southeastern flank of the lava dome. Numerous small rockfalls were observed falling from the S, E, and NE flanks of the dome, adding to the talus in the upper reaches of the Tar River valley. Helicopter observations indicated continued dome growth, particularly in the SE.

Source: Montserrat Volcano Observatory (MVO)


18 January-24 January 2006

Activity at Soufrière Hills remained elevated during 13-20 January 2006. The seismic network recorded 61 rockfall signals, 17 long-period earthquakes, and 15 long-period rockfall signals. Measured sulfur dioxide fluxes ranged between 350 and 1,160 metric tons/day (t/d); the weekly average was 767 t/d. Images taken by the remote camera on Perches Mountain show that the dome continued to grow over a broad sector extending from the SW around to the NE. A central spine was first observed on 17 January when cloud cleared briefly from the. Continuing small rockfalls from the S, E, and NE flanks of the dome are visible at, and are adding to the talus in the upper reaches of the Tar River valley.

Source: Montserrat Volcano Observatory (MVO)


11 January-17 January 2006

Activity at Soufrière Hills remained at elevated levels during 6-13 January. Photographs revealed that the lava dome continued to grow throughout the report period over a broad sector extending from the E around to the N. Numerous small rockfalls continued from the E and NE flanks of the lava dome, adding talus in the upper reaches of the Tar River valley. The sulfur-dioxide flux averaged 724 metric tons per day.

Source: Montserrat Volcano Observatory (MVO)


4 January-10 January 2006

Activity at Soufrière Hills remained at elevated levels during 30 December to 6 January. Photographs revealed that the lava dome continued to grow throughout the report period over a broad sector extending from the SW around to the NE. Numerous small rockfalls continued from the S, E, and NE flanks of the lava dome, adding talus in the upper reaches of the Tar River valley to the NE. The sulfur-dioxide flux averaged 522 metric tons per day.

Source: Montserrat Volcano Observatory (MVO)


28 December-3 January 2006

Volcanic and seismic activity at Soufrière Hills remained at elevated levels during 23-30 December. Images indicated that the lava dome continued to grow over a broad sector extending from the SW around to the NE. Numerous small rockfalls continued on the S, W, and NE sides of the lava dome, adding to the talus in the upper reaches of the Tar River Valley to the NE. The sulfur-dioxide flux averaged 510 metric tons per day.

Source: Montserrat Volcano Observatory (MVO)


21 December-27 December 2005

Volcanic and seismic activity at Soufrière Hills remained elevated during 16-23 December. Images revealed that the lava dome continued to grow during the report period. Growth occurred over a broad sector extending from the SW around to the NE. Vertical growth was focused to the S and SW, with lateral growth in the E and SE sectors. Numerous small rockfalls traveled down the S, E, and NE flanks of the lava dome, adding to the talus in the upper reaches of the Tar River Valley to the NE. The sulfur-dioxide flux averaged 415 metric tons per day.

Source: Montserrat Volcano Observatory (MVO)


14 December-20 December 2005

During 9-16 December, seismic and volcanic activity remained at elevated levels at Soufrière Hills. Images taken during the report period showed that the lava dome continued to grow. Growth occurred over a broad sector extending from the SW around to the NE, but was mostly focused towards the S and SW. Numerous small rockfalls traveled down the S, E, and NE flanks of the lava dome, adding to the talus in the upper reaches of the Tar River valley. The sulfur-dioxide flux averaged 489 metric tons per day.

Source: Montserrat Volcano Observatory (MVO)


7 December-13 December 2005

Activity at Soufrière Hills remained at elevated levels during 2-9 December. Camera images of the lava dome indicated that extrusion rates were slightly lower than during previous report periods. The height of the lava dome only slightly increased. Most growth was focused towards the SE where the flank had been pushed out laterally. Incandescence was visible in this area. Numerous small rockfalls occurred on the SE flank, adding to the talus apron in the upper reaches of the Tar River valley. The sulfur-dioxide flux averaged 1,114 metric tons per day.

Source: Montserrat Volcano Observatory (MVO)


30 November-6 December 2005

Activity at Soufrière Hills remained elevated during 25 November-2 December 2005. The seismic network recorded 158 rockfall signals, one volcano-tectonic earthquake, 93 long-period earthquakes, two hybrid earthquakes, and 17 long-period rockfall signals during the reporting period. Measured sulfur dioxide fluxes varied between 600 metric tons per day (t/d) measured on 30 November and 830 t/d on 26 November, with a weekly average of 690 t/d. Dome growth continued on all flanks, although activity was most intense on the S and E; incandescence was observed at night on the SE and E flanks throughout the reporting period. Large rockfalls and small pyroclastic flows collapsed off the E flank of the dome during this period and entered the upper reaches of the Tar River Valley.

Source: Montserrat Volcano Observatory (MVO)


23 November-29 November 2005

Activity at Soufrière Hills increased during 18-25 November in comparison to the previous week. Growth of the volcano's lava dome was focused towards the E and S, with minor activity to the S and W. Continuous incandescence was observed at night on the SE and E sides of the lava dome. A pyroclastic flow was seen in the upper reaches of the Tar River Valley on 22 November. Minor ash emissions occurred from the volcano, including one on the afternoon of 24 November that sent an ash cloud several hundred meters above the volcano's summit. Measurements of sulfur-dioxide emissions were only possible on 2 days due to the wind direction. An average of 1,055 metric tons of sulfur dioxide was measured daily.

Source: Montserrat Volcano Observatory (MVO)


16 November-22 November 2005

Seismic and volcanic activity at Soufrière Hills remained at elevated levels during 11-18 November. Clear observations of the lava dome on the morning of 18 November indicated that it continued to grow and was shedding rockfalls to the E, S, W, and NW. A pyroclastic flow was observed in the Tar River valley on 15 November and reached to within a kilometer of the sea. The ash cloud associated with this event rose to ~2.1 km (~7,000 ft) a.s.l. The sulfur-dioxide flux averaged 650 metric tons per day.

Source: Montserrat Volcano Observatory (MVO)


9 November-15 November 2005

Volcanic and seismic activity at Soufrière Hills remained elevated during 4-11 November. Images showed incandescence at the lava dome at night, and growth of the E, S, and SE sectors. Radar imaging of the lava dome indicated that its volume was about 6.5 million cubic meters, suggesting a growth rate over the past 2 weeks between 1.3 and 1.8 cubic meters per second. The sulfur-dioxide flux averaged 445 metric tons per day.

Source: Montserrat Volcano Observatory (MVO)


2 November-8 November 2005

Volcanic and seismic activity remained elevated at Soufrière Hills during 28 October to 4 November. Observations on 4 November confirmed that lava-dome growth continued, predominantly above the volcano's S flank.

Source: Montserrat Volcano Observatory (MVO)


26 October-1 November 2005

Volcanic and seismic activity at Soufrière Hills remained at elevated levels during 21-28 October. On 26 October around 2400, a pyroclastic flow traveled ~2 km down the volcano's NE flank. The pyroclastic flow was confined to the Tar River Valley. During the report week, the lava dome continued to grow and incandescence was visible at night. The sulfur-dioxide flux averaged 420 metric tons per day (t/d), below the long-term eruption average of 500 t/d. The hydrogen-chloride to sulfur-dioxide ratio measured on 26 October was at 1.3. According to the Washington VAAC, a pilot reported observing a thin layer of ash at a height of ~2.4 km (8,000 ft) a.s.l. above St. Croix on 28 October at 1010.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


19 October-25 October 2005

During 14-21 October, elevated seismic and volcanic activity continued at Soufrière Hills. A majority of the volcano-tectonic earthquakes recorded during the week occurred during a 36-hour period over 17-18 October when a lobe on the S part of the lava dome was developing. At this time there were also a large number of rockfalls, which continued until 20 October. The daily sulfur-dioxide flux averaged 658 metric tons per day (t/d), above the long-term eruption average of 500 t/d. The hydrogen-chloride versus sulphur-dioxide ratio increased to about 1.15. Limited camera observations suggested that the lava dome was growing at a rate of less than 2 cubic meters per second.

Source: Montserrat Volcano Observatory (MVO)


12 October-18 October 2005

Volcanic and seismic activity at Soufrière Hills remained at elevated levels during 7-14 October. Lava-dome growth mostly occurred on the W side of the dome, which was largely obscured by clouds and steam. Observations suggested that the lava-dome growth rate increased, with preliminary calculations suggesting a rate of at least 2 cubic meters per second. Incandescence was visible at the lava dome on a video camera at night. The sulfur-dioxide flux averaged 580 metric tons per day (t/d), above the long-term eruption average of 500 t/d. The hydrogen-chloride versus sulfur-dioxide ratio increased to about 1.

Source: Montserrat Volcano Observatory (MVO)


28 September-4 October 2005

Volcanic and seismic activity at Soufrière Hills remained at elevated levels during 23-30 September. Slow lava-dome growth continued at the volcano. The daily sulfur-dioxide flux averaged 950 metric tons per day (t/d), above the long-term eruption average of 500 t/d.

Source: Montserrat Volcano Observatory (MVO)


21 September-27 September 2005

Volcanic and seismic activity at Soufrière Hills remained at elevated levels during 16-23 September. Observations on 20 September suggested that slow lava-dome growth continued. The daily sulfur-dioxide flux averaged 680 metric tons per day (t/d), above the long-term eruption average of 500 t/d.

Source: Montserrat Volcano Observatory (MVO)


14 September-20 September 2005

Activity at Soufrière Hills remained at elevated levels during 9-16 September. Observations made during the week suggested that slow lava-dome growth continued on the dome's eastern side, but the western side was obscured by steam. The sulfur-dioxide flux averaged 533 metric tons per day (t/d), slightly above the long-term eruption average of 500 t/d.

Source: Montserrat Volcano Observatory (MVO)


7 September-13 September 2005

Activity at Soufrière Hills remained at elevated levels during 2-9 September. Observations made on 5 September suggested that slow lava-dome growth continued. The sulfur-dioxide flux averaged 410 metric tons per day (t/d), below the long-term eruption average of 500 t/d.

Source: Montserrat Volcano Observatory (MVO)


24 August-30 August 2005

Volcanic and seismic activity at Soufrière Hills remained at elevated levels during 19-26 August. During the report week, there was little ash venting and the daily sulfur-dioxide flux averaged 900 metric tons per day (t/d), above the long-term eruption average of 500 t/d.

Source: Montserrat Volcano Observatory (MVO)


17 August-23 August 2005

Volcanic and seismic activity remained at elevated levels at Soufrière Hills during 12-19 August. Periodic ash venting continued, with a vigorous episode occurring on 18 August at 1800. On 16 August, the presence of a small blocky lava dome with talus slopes was confirmed. There was some ash venting from the dome, but no significant rockfalls were seen. The daily recorded sulfur-dioxide flux averaged 570 metric tons per day (t/d), above the long-term eruption average of 500 t/d.

Source: Montserrat Volcano Observatory (MVO)


10 August-16 August 2005

Volcanic and seismic activity at Soufrière Hills remained at elevated levels during 5-12 August. The volcano's seismic network recorded three volcano-tectonic, three hybrid, and five long-period earthquakes. It also recorded 14 rockfall signals. Periodic ash venting continued during the report period, with a vigorous episode on 6 August sending a plume to ~1.8 km above the volcano (or ~9,400 ft. a.s.l.). Evidence of uplift and fracturing were observed on the crater floor, and an area of blocky lava resembling a small lava dome was observed. Due to poor visibility further observations will be necessary to determine if the feature is a new dome or was caused by the collapse, or uplift, of old dome rock.

Source: Montserrat Volcano Observatory (MVO)


3 August-9 August 2005

Seismic activity at Soufrière Hills remained elevated from 3 to 9 August. Analysis of the ash from the 28 June explosion showed no evidence for the involvement of fresh magma.The daily recorded sulfur dioxide flux varied from 300 metric tons/day (t/d) on 4 August to 2,200 t/d on 2 August, with an average of 986 t/d for the week. This is above the long-term average for the eruption of 500 t/d.

Source: Montserrat Volcano Observatory (MVO)


27 July-2 August 2005

Seismic and volcanic activity at Soufrière Hills remained at elevated levels during 22-29 July. The seismic network recorded 29 volcano-tectonic, four hybrid, and five long-period earthquakes. It also recorded one explosion and 23 rockfalls. An explosion on 27 July at 0114 deposited ash between Plymouth on the island's W side, and Brades on the island's NW side. The explosion was similar to, but smaller than, an explosion on 18 July. Occasional ash venting also occurred during the report week. The daily recorded sulfur-dioxide flux averaged 510 metric tons per day (t/d), slightly above the long-term average of 500 t/d.

Source: Montserrat Volcano Observatory (MVO)


20 July-26 July 2005

Seismic and volcanic activity remained at elevated levels at Soufrière Hills during 15-22 July. The seismic network recorded 19 volcano-tectonic, 16 hybrid, and 13 long-period earthquakes. It also recorded 11 rockfalls and one explosion. The explosion occurred on 18 July at 0301 and deposited ash between Fogarty Hill in the NW of the island and Brodericks Yard in the SW. The deepest ash deposits were recorded at Weekes. An ash plume rose to at least 6.1 km (20,000 ft). The explosion was similar to, but slightly larger than, an explosion on 3 July. Analysis of ash from an explosion on 28 June showed no evidence for the involvement of fresh magma. The sulfur-dioxide flux reached an average of 608 metric tons per day during the report period.

Source: Montserrat Volcano Observatory (MVO)


13 July-19 July 2005

Volcanic and seismic activity at Soufrière Hills remained at elevated levels during 8-15 July. The seismic network recorded 10 hybrid and two volcano-tectonic earthquakes during the report period. Also, several ash-venting events occurred and there was an explosion on 9 July at 2000. The average daily sulfur-dioxide flux remained above the average for the eruption. FTIR measurements of the hydrogen chloride to sulfur dioxide ratio on 12 July were consistent with values measured since the current eruptive pause began in July 2003.

Source: Montserrat Volcano Observatory (MVO)


6 July-12 July 2005

During 1-8 July, seismic and volcanic activity at Soufrière Hills remained at elevated levels. The seismic network recorded 15 hybrid earthquakes, 11 long-period earthquakes, 9 volcano-tectonic earthquakes, and 11 rockfalls. Periodic ash venting continued and an explosion occurred on 3 July at 0130, which was similar to an explosion on 28 June. The reversal of deformation to an inflationary trend that began in mid-July continued during the report period. The daily recorded sulfur-dioxide flux varied from 241 metric tons per day (t/d) on 4 July to 1700 t/d on 1 July, with an average of 767 t/d for the week. This was above the long-term average for the eruption of 500 t/d.

Source: Montserrat Volcano Observatory (MVO)


29 June-5 July 2005

During 24 June to 1 July, seismic and volcanic activity at Soufrière Hills was elevated in comparison to the previous week. Periodic episodes of intense ash venting continued during the report period, culminating in an explosive event beginning on 28 June at 1306. During the event, ballistics were ejected onto the Farrell's plain (to the NW) and a column collapse produced pyroclastic flows. The pyroclastic flows reached the sea at the Tar River delta (to the NE) and a smaller volume of material flowed into the top of Tyre's Ghaut (to the N). Ash analyses from a venting episode on 13 June did not indicate the presence of fresh magma.

Preliminary analysis of recent ground deformation data from the GPS network at the volcano showed that deflation during April to mid June 2005 had later reversed, and the volcano appeared to be inflating. The daily recorded sulfur-dioxide flux varied from 300 metric tons per day (t/d) on 28 June to 700 t/d on 29 June, with an average of 470 t/d for the week.

Source: Montserrat Volcano Observatory (MVO)


22 June-28 June 2005

Seismic and volcanic activity at Soufrière Hills were at elevated levels during 17-24 June. The seismic network at the volcano recorded 8 hybrid earthquakes, 5 long-period earthquakes, 4 volcano-tectonic earthquakes, and 3 rockfalls. On 27 June a steam and ash cloud at ~3 km (9,800 ft) a.s.l. was reported to be drifting W. The daily recorded sulphur dioxide flux varied from a low of 430 metric tons per day (t/d) on 20 June, to a maximum of 1150 t/d on 23 June, with an average of 627 t/d for the week. By 28 June satellite imagery shows a plume of ash and steam at ~1.8 km (5,900 ft) a.s.l. extending NW of the volcano.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


15 June-21 June 2005

Seismic and volcanic activity at Soufrière Hills were at elevated levels during 10-17 June. The seismic network at the volcano recorded 17 hybrid earthquakes, 20 long period earthquakes, 46 volcano-tectonic earthquakes, and 7 rockfalls. A period of ash venting that began on 13 June at 0600 declined in intensity during the report week. The ash venting was caused by the rapid release of steam and other volcanic gases, possibly triggered by intense rainfall on the night of 12 June. The daily recorded sulfur-dioxide flux varied from 170 metric tons per day (t/d) on 10 June, to a maximum of 750 t/d on 14 June, with an average of 460 t/d for the week.

Source: Montserrat Volcano Observatory (MVO)


8 June-14 June 2005

On 13 June at 0600 there was an increase in volcanic and seismic activity at Soufrière Hills. A series of volcano-tectonic earthquakes was accompanied by low-level tremor and a period of ash venting. An ash plume reached a height of ~2.4 km (7,900 ft) a.s.l and drifted NE, depositing light ash in Lookout, Geralds, and St. Peters. Activity decreased significantly after 0900.

Prior to the activity increase, during 3-10 June, the seismic network at Soufrière Hills recorded 17 volcano-tectonic earthquakes and one rockfall. Steam venting continued on the NW side of the crater. The daily recorded sulfur-dioxide flux varied from a low of 142 metric tons per day (t/d) on 4 June to a maximum of 671 t/d on 7 June, with an average of 399 t/d for the week. This was below the eruption's long-term average of 500 t/d.

Source: Montserrat Volcano Observatory (MVO)


1 June-7 June 2005

The seismic network at Soufrière Hills recorded 8 volcano-tectonic earthquakes during 27 May to 3 June. Steam venting continued on the NW side of the crater. The daily recorded sulfur-dioxide flux ranged from a low of 167 metric tons per day (t/d) on 2 June to a maximum of 392 t/d on 30 May, with an average of 261 t/d for the week. This was below the long-term eruption average of 500 t/d.

Source: Montserrat Volcano Observatory (MVO)


25 May-31 May 2005

During 20-27 May, the seismic network at Soufrière Hills recorded 67 volcano-tectonic earthquakes (mostly during 20-21 May) and steam venting continued on the NW side of the crater. A sulfur-dioxide flux of 880 metric tons was recorded on 26 May, above the long-term average of 500 metric tons per day.

Source: Montserrat Volcano Observatory (MVO)


18 May-24 May 2005

During 13-20 May, the seismic network at Soufrière Hills recorded 18 volcano-tectonic earthquakes (most occurred on 17 May) and 3 hybrid earthquakes. Steam venting that began on the NW side of the crater on 15 April continued. The daily recorded sulfur-dioxide flux varied from a low of 222 metric tons per day (t/d) on 16 May to a maximum of 363 t/d on 14 May, with an average of 286 t/d. This was below the eruption's long-term average of 500 t/d.

Source: Montserrat Volcano Observatory (MVO)


11 May-17 May 2005

The seismic network recorded 38 volcano-tectonic (VT) earthquakes, one hybrid earthquake and one rockfall during 6-13 May. Steam venting on the NW side of the crater continued. The daily recorded sulfur dioxide flux varied from a low of 221 metric tons per day (t/d) on 11 May to a maximum of 537 t/d on the 9th. The average of the six measurements during the week was 398 t/d, below the long-term eruption average of 500 t/d.

Source: Montserrat Volcano Observatory (MVO)


4 May-10 May 2005

Steam venting continued during the week of 29 April-6 May from the NW side of the crater. Sulfur dioxide flux measurements were made every day, resulting in an average of 439 metric tons/day, below the long-term average for the eruption (500 tons/day).

Source: Montserrat Volcano Observatory (MVO)


27 April-3 May 2005

Steam venting that began at the NW side of Soufrière Hills' crater on 15 April continued during 22-29 April. An average sulfur-dioxide flux of 304 metric tons per day was measured during 4 days in the report week. This value was below the long-term eruption average of 500 metric tons per day.

Source: Montserrat Volcano Observatory (MVO)


20 April-26 April 2005

Beginning on 15 April, vigorous steam-and-ash venting occurred on the NW side of Soufrière Hills crater. It was accompanied by tremor, which decreased during the following days and stopped on 18 April. Rainfall on 21 April caused a small mudflow in the Belham River Valley to the NE of the volcano. There was light ashfall W of the volcano during 23-24 April. An average of 365 metric tons of sulfur dioxide was measured daily, below the long-term average for the eruption of 500 metric tons per day.

Source: Montserrat Volcano Observatory (MVO)


16 March-22 March 2005

Seismic activity at Soufrière Hills remained at low levels during 11-18 March. The seismic network recorded six volcano-tectonic earthquakes and one rockfall. The sulfur-dioxide flux ranged between 235 and 630 metric tons per day, with an average of 425 metric tons per day. This was below the long-term average for the eruption of 500 metric tons per day.

Source: Montserrat Volcano Observatory (MVO)


9 March-15 March 2005

Seismicity remained at low levels at Soufrière Hills during 4-11 March. The sulfur-dioxide flux remained around the same level as the previous week, with an average of 695 metric tons recorded daily. During the week, a strong sulfurous smell was noticed across the northern part of Montserrat. MVO attributed this to a deviation from the normal prevailing wind direction.

Source: Montserrat Volcano Observatory (MVO)


2 March-8 March 2005

MVO reported that during 25 February to 4 March, seismic activity at Soufrière Hills remained at low levels. The sulfur-dioxide flux remained fairly stable, averaging 672 metric tons per day. FTIR (Fourier-Transform Infrared Spectroscopy) measurements on 3 March yielded a hydrogen chloride to sulphur dioxide mass ratio of 0.35, showing no significant change since the last measurement in February. Views of the entire summit on 3 March revealed that there were no surficial changes at the volcano. There was still a small pond in the 3 March 2004 explosion pit.

A news article reported that hazy skies over St. Martin (NE of Soufrière Hills) and the surrounding islands on 6 March were the result of increased activity at Soufriere Hills. Several people in the eastern section of St. Martin reported a thin film of "dust" on their homes and vehicles. According to the Washington VAAC, a very faint area of possible ash was visible on satellite imagery on 6 March extending NE.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC), The Daily Herald


2 February-8 February 2005

During 28 January- 4 February, seven long-period, one volcano-tectonic, and two hybrid earthquakes were recorded at Soufrière Hills. On 28 January, the daily sulfur-dioxide flux was 410 metric tons. No significant morphological changes were observed at the volcano's edifice during a flight on 1 February.

Source: Montserrat Volcano Observatory (MVO)


19 January-25 January 2005

During 14-21 January, at Soufrière Hills two hybrid earthquakes and two rockfalls were recorded by the seismic network. Sulfur-dioxide flux rates of 300 and 380 metric tons per day were recorded on 15 and 16 January, respectively. No significant change in the morphology of the volcanic edifice was seen during an observational flight on 19 January.

Source: Montserrat Volcano Observatory (MVO)


29 December-4 January 2005

During 24-31 December, one long-period, six hybrid, and two volcano-tectonic earthquakes were recorded at Soufrière Hills. The sulfur-dioxide flux averaged 410 metric tons per day and ranged between 300 and 550 metric tons per day.

Source: Montserrat Volcano Observatory (MVO)


22 December-28 December 2004

During 17-24 December, six hybrid earthquakes and one volcano-tectonic earthquake were recorded by the seismic network at Soufrière Hills. Sulfur-dioxide flux ranged 200-500 metric tons per day, with an average of 325 metric tons per day. An observation flight revealed the continued existence of an explosion-pit pond and no lava-dome growth.

Source: Montserrat Volcano Observatory (MVO)


15 December-21 December 2004

During 10-17 December, at Soufrière Hills six hybrid earthquakes and seven volcano-tectonic earthquakes were recorded by the seismic network. The sulfur-dioxide flux ranged 290-450 metric tons per day, averaging 360 tons per day. During the late afternoon of 15 December, heavy rain caused a mudflow in the Belham Valley.

Source: Montserrat Volcano Observatory (MVO)


24 November-30 November 2004

During 19-26 November, the seismic network at Soufrière Hills recorded 25 hybrid earthquakes, five volcano-tectonic earthquakes, three rockfalls, and one long-period earthquake. The sulfur-dioxide flux was between 125 and 330 metric tons per day, averaging 195 metric tons per day during the report period.

Source: Montserrat Volcano Observatory (MVO)


10 November-16 November 2004

During 8-15 November, volcanic and seismic activity at Soufrière Hills remained elevated. The seismic network recorded one rockfall and nine hybrid earthquakes. Weather conditions limited measurements of sulfur dioxide emissions during 8-15 November. Reliable data were only available for two days when the plume blew over the sensors, yielding SO2-flux estimates of 141 and 501 metric tons per day. Circumstances prevented visual status reports on the crater.

Source: Montserrat Volcano Observatory (MVO)


3 November-9 November 2004

During 29 October to 5 November, volcanic and seismic activity at Soufrière Hills remained elevated. The seismic network recorded one rockfall, 33 hybrid earthquakes, and 39 volcano-tectonic earthquakes. The increased hybrid and volcano-tectonic activity was thought to be related to rainfall. In association with the rainfall, minor mudflow activity was recorded on 1 and 3 November. The sulfur-dioxide flux averaged about 290 metric tons per day, with a high of 440 metric tons on 30 October. An observation flight over the volcano on 4 November revealed the continued existence of standing water in the explosion pit produced by the 3 March 2004 event and no evidence of a re-start of lava-dome growth.

Source: Montserrat Volcano Observatory (MVO)


27 October-2 November 2004

Volcanic and seismic activity at Soufrière Hills continued to be at elevated levels during 22-29 October. The seismic network recorded one volcano-tectonic and 40 hybrid earthquakes. Like the previous week, the increased hybrid earthquake activity was thought to be related to heavy rainfall during the report period. In association with the heavy rainfall, minor mudflow activity was recorded and observed in the Belham River. An observation flight over the volcano on 28 October revealed the continued existence of standing water in the explosion pit produced by the 3 March 2004 event and no evidence of a re-start of lava-dome growth.

Source: Montserrat Volcano Observatory (MVO)


20 October-26 October 2004

Seismic activity at Soufrière Hills was at elevated levels during 15-22 October in comparison to previous weeks. The seismic network recorded four rockfall events and 49 hybrid earthquakes, and one volcano-tectonic earthquake. MVO scientists thought that increased hybrid earthquake activity was related to heavy rainfall during the week. The sulfur dioxide gas flux varied from 250 to 1,100 metric tons per day during the report period. Mudflows were recorded during 15, 19, and 21 October.

Source: Montserrat Volcano Observatory (MVO)


13 October-19 October 2004

Volcanic and seismic activity at Soufrière Hills remained at slightly elevated levels during 8-15 October, as they have since mid-September 2004. The seismic network recorded one rockfall and nine hybrid earthquakes. Sulfur-dioxide flux measurements were only possible on 2 days; 156 and 553 metric tons per day were recorded.

Source: Montserrat Volcano Observatory (MVO)


6 October-12 October 2004

Volcanic and seismic activity at Soufrière Hills remained at slightly elevated levels during 1-8 October. The seismic network recorded one rockfall, two long-period earthquakes, and eight hybrid earthquakes. The sulfur-dioxide flux ranged between 187 and 1,144 metric tons per day, with a weekly average of 462 metric tons per day.

Source: Montserrat Volcano Observatory (MVO)


29 September-5 October 2004

Volcanic and seismic activity at Soufrière Hills during 24 September to 1 October remained slightly elevated, as has been the case for several weeks. The seismic network recorded three rockfalls, one long-period earthquake, and eight hybrid earthquakes. Sulfur-dioxide flux ranged between 200 and 540 metric tons per day, with a weekly average of 340 metric tons.

Source: Montserrat Volcano Observatory (MVO)


22 September-28 September 2004

Volcanic and seismic activity at Soufrière Hills remained slightly elevated throughout 17-24 September. The seismic network recorded two rockfalls, two long-period earthquakes, and eight hybrid earthquakes. The sulfur-dioxide flux averaged 312 metric tons per day, reaching a maximum of 454 metric tons on 18 September. An unusual wind direction occasionally brought the volcanic plume across inhabited areas, causing people in the area to experience the plume's characteristic sulfur smell.

Source: Montserrat Volcano Observatory (MVO)


15 September-21 September 2004

Activity at Soufrière Hills during 10-17 September was slightly elevated. The seismic network recorded one rockfall, one long-period, and 14 hybrid earthquakes. The weekly average for daily sulfur dioxide emissions was 180 metric tons. Unusual winds brought the volcanic plume across inhabited areas from time to time, causing people to experience its characteristic sulfurous smell. Mudflows, due to heavy rain, were recorded on 14 and 16 September.

Source: Montserrat Volcano Observatory (MVO)


8 September-14 September 2004

Volcanic and seismic activity at Soufrière Hills remained at low levels during 3-10 September. The seismic network recorded two rockfalls and one volcano-tectonic earthquake. Sulfur-dioxide flux ranged between 175 and 405 metric tons per day, averaging 270 metric tons daily. A small pond, first observed during the week of 27 August, was still visible in the explosion pit formed on 3 March 2004.

Source: Montserrat Volcano Observatory (MVO)


1 September-7 September 2004

Volcanic and seismic activity at Soufrière Hills remained at low levels during 27 August to 3 September. The seismic network recorded two hybrid earthquakes. The sulfur-dioxide flux ranged between 240 and 456 metric tons per day. A small pond was observed on the volcano for the first time since the beginning of the eruption. The water in the pond pooled in the explosion pit formed on 3 March 2004.

Source: Montserrat Volcano Observatory (MVO)


25 August-31 August 2004

Seismic and volcanic activity at Soufrière Hills remained at low levels during 20-27 August. The seismic network recorded one hybrid earthquake and one rockfall. Sulfur-dioxide flux ranged between 175 and 310 metric tons per day.

Source: Montserrat Volcano Observatory (MVO)


18 August-24 August 2004

Volcanic and seismic activity at Soufrière Hills remained at low levels during 13-20 August. The seismic network recorded one hybrid earthquake, one volcano-tectonic earthquake, and one rockfall. Sulfur-dioxide flux measurements were generally around 200 metric tons per day.

Source: Montserrat Volcano Observatory (MVO)


11 August-17 August 2004

Volcanic and seismic activity at Soufrière Hills remained at low levels during 6-13 August. The seismic network recorded one hybrid earthquake and three rockfalls. The sulfur-dioxide flux varied between about 125 and 300 metric tons per day, averaging 200 metric tons. Ground deformation data from July suggested a reversal in trend from shortening between stations across the volcano to slight extension.

Source: Montserrat Volcano Observatory (MVO)


4 August-10 August 2004

Volcanic and seismic activity at Soufrière Hills remained at low levels during 30 July to 6 August. The seismic network recorded one hybrid earthquake and eight rockfalls. The sulfur-dioxide flux varied between 90 and 280 metric tons per day, which was lower than the long-term eruption average of ~500 metric tons per day.

Source: Montserrat Volcano Observatory (MVO)


28 July-3 August 2004

Volcanic and seismic activity remained at low levels at Soufrière Hills during 23-30 July. The seismic network recorded two hybrid earthquakes and eight rockfalls. The sulfur-dioxide flux ranged between 175 and 300 metric tons per day, which is lower than the long-term eruption average of ~500 metric tons per day.

Source: Montserrat Volcano Observatory (MVO)


21 July-27 July 2004

Volcanic and seismic activity at Soufrière Hills remained at low levels during 16-23 July. The seismic network recorded seven hybrid earthquakes and seven rockfalls. No long-period events or volcano-tectonic earthquakes were recorded. The sulfur-dioxide flux on 16 and 23 July was 170 and 400 metric tons per day, respectively.

Source: Montserrat Volcano Observatory (MVO)


7 July-13 July 2004

During 2-9 July, low-level activity continued at Soufrière Hills. MVO reported 4 volcano-tectonic earthquakes, 8 hybrid earthquakes, and 10 rockfalls. Emission rates of sulphur dioxide gas (120 to 160 tonnes per day) reached the lowest levels since the collapse event of 12-13 July 2003.

Source: Montserrat Volcano Observatory (MVO)


30 June-6 July 2004

Volcanic and seismic activity at Soufrière Hills were at low levels during 25 June to 2 July. The seismic network recorded 2 long-period earthquakes, 6 volcano-tectonic earthquakes, 5 hybrid earthquakes, and 8 rockfalls. A peak sulfur-dioxide flux of ~365 metric tons was measured on 27 June.

Source: Montserrat Volcano Observatory (MVO)


23 June-29 June 2004

Activity at Soufrière Hills remained at low levels during 18-25 June. Most seismic activity occurred during 18-20 June, with extremely low seismicity during the remainder of the report period. The upper portions of the lava-dome complex within the crater were visible for the first time since 7 May 2004, revealing that parts of the dome had been lost. This explained the rockfall signals recorded during the previous weeks. Technical problems prevented measurements of the sulfur-dioxide flux.

Source: Montserrat Volcano Observatory (MVO)


16 June-22 June 2004

Activity at Soufrière Hills remained at low levels during 11-18 June. The seismic network recorded five hybrid earthquakes and 20 rockfalls. The sulfur-dioxide flux was low during the majority of the report period, reaching a peak of ~480 metric tons on 14 June.

Source: Montserrat Volcano Observatory (MVO)


9 June-15 June 2004

Activity at Soufrière Hills remained at low levels during 4-11 June. The seismic network recorded three hybrid earthquakes and nine "mixed events," which were thought to have originated at shallow depths within the remnants of the lava dome and around the top of the conduit. The sulfur-dioxide flux peaked at ~790 tons on 7 June and decreased sharply to ~170 tons per day by the end of the report period.

Source: Montserrat Volcano Observatory (MVO)


2 June-8 June 2004

During 28 May to 4 June, activity at Soufrière Hills remained low with four hybrid and 16 mixed earthquakes recorded. Sulfur-dioxide emissions fluctuated but remained low.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


26 May-1 June 2004

Volcanic and seismic activity at Soufrière Hills remained at low levels during 21-28 May. Seismicity was dominated by signals from mudflows associated with the heavy rain of 21 May. The mudflows occurred during about 1420-1636 and were followed by a swarm of 44 small earthquakes. The sulfur-dioxide flux varied, reaching values between about 225 and 920 tons per day.

Source: Montserrat Volcano Observatory (MVO)


19 May-25 May 2004

Volcanic and seismic activity at Soufrière Hills during 14-21 May remained at low levels. On 21 May intense rainfall produced large mudflows in the Belham Valley. At the peak of the activity, the entire width of the valley floor at Belham Bridge was flooded and standing waves up to 2 m high were observed. The sulfur-dioxide flux was low for most of the report period.

Source: Montserrat Volcano Observatory (MVO)


12 May-18 May 2004

Volcanic and seismic activity at Soufrière Hills remained at low levels during 7-14 May. Spasmodic tremor ceased on 7 May, ending a protracted period of low-to-moderate amplitude tremor that began on 15 March. The sulfur-dioxide flux was at low-to-moderate levels, reaching the lowest recorded value on 13 May (146 metric tons per day) since the major explosions and collapse event during 12-15 July 2003.

Source: Montserrat Volcano Observatory (MVO)


5 May-11 May 2004

Volcanic and seismic activity at Soufrière Hills remained at low levels during 30 April to 7 May. Seismicity during the report period was dominated by low-level tremor, switching to spasmodic tremor during the early hours of 6 May. A small amount of ash venting from the volcano's summit occurred on 2 May around 1815. The sulfur-dioxide flux was low (200-300 metric tons per day) for most of the report period before increasing sharply to ~670 metric tons on 6 May.

Source: Montserrat Volcano Observatory (MVO)


28 April-4 May 2004

Volcanic activity at Soufrière Hills was at low levels during 23-30 April. Seismicity included low-level tremor, spasmodic tremor, and small numbers of long-period and hybrid earthquakes. A large hybrid earthquake on 29 April at 1540 resulted in a small amount of ash venting from the summit. The sulfur-dioxide flux was low throughout the report period.

Source: Montserrat Volcano Observatory (MVO)


21 April-27 April 2004

Volcanic and seismic activity at Soufrière Hills were at low levels during 16-23 April. Seismicity was characterized by periods of continuous and spasmodic tremor punctuated by long-period hybrid earthquakes. Continuous low-level tremor occurred on 16 April with a second episode during 18-19 April. The sulfur-dioxide flux varied during the report period, reaching a peak of 1,030 metric tons per day on 16 April.

Source: Montserrat Volcano Observatory (MVO)


14 April-20 April 2004

During 10-16 April, activity at Soufrière Hills remained low with only one long-period earthquake recorded. Nearly continuous low-level tremor and moderate sulfur-dioxide emissions occurred throughout the reporting week.

Source: Montserrat Volcano Observatory (MVO)


7 April-13 April 2004

During 2-9 April, seismic and volcanic activity at Soufrière Hills was at low-to-moderate levels. Seismicity was dominated by near-continuous low-to-moderate level tremor. The sulfur-dioxide flux was low during most of the report period.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


31 March-6 April 2004

Seismic and volcanic activity were at moderate levels at Soufrière Hills during 26 March to 2 April. Seismicity was dominated by near-continuous low-to-moderate tremor. Vigorous steam venting was visible from several areas of the crater, but no new lava-dome growth occurred. The sulfur-dioxide flux remained at moderate levels.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


24 March-30 March 2004

During 19-26 March, activity remained elevated at Soufrière Hills. The seismic network recorded four long-period and seven hybrid earthquakes. Continuous low-level tremor was interrupted by several periods of moderate-level tremor lasting from less than 1 hour to 12 hours. Sulfur-dioxide flux ranged between 550 and 700 metric tons per day. On 29 March at 0745, the Washington VAAC reported that a ~9-km-wide ash plume was observed at a height of ~1 km a.s.l. The plume initially drifted SW until about 1015 the same day when it was observed in satellite imagery drifting NE. On 30 March an ash plume was observed that reached a height of ~2 km and drifted NE.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


17 March-23 March 2004

Seismic and volcanic activity at Soufrière Hills during 12-19 March increased in comparison to the previous week. Seismicity was dominated by moderate-to-strong tremor beginning around 0300 on 15 March, with five episodes of moderate tremor. The tremor was accompanied by gas-and-ash venting. At 1622 on 15 March an increase in the energy level of the tremor was recorded and a convecting ash cloud rose to ~2 km above the volcano. At 1745 emergent pulsating ash clouds were observed, although no eruption column was established. Ash drifted WSW away from populated areas over Plymouth, Amersham, and areas farther S. Tremor remained at elevated levels throughout the night peaking around 2245, coincident with a vigorous venting episode that produced an ash cloud to ~4.5 km above the volcano accompanied by lightning. Vigorous gas-and-ash venting continued through 16 March. The amount of ash in the gas plume decreased during 17 March and ash venting had all but ceased by the end of the day. The sulfur-dioxide flux remained at moderate levels during the report period.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


10 March-16 March 2004

Following a lava-dome collapse at Soufrière Hills on 3 March, activity was relatively lower during 5-12 March. Around 0330 on 10 March a short period of elevated seismic activity lasting around 10-20 minutes occurred. Later that day fresh pyroclastic-flow deposits were observed toward the NE in the upper reaches of the Tar River Valley. Several short periods of ash-and-steam venting were observed during 9-12 March, with ash deposited as far N as St. Georges Hill. The sulfur-dioxide flux peaked at 1,250 metric tons on 9 March.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


3 March-9 March 2004

Volcanic and seismic activity increased significantly at Soufrière Hills during 27 February to 5 March, with a lava-dome collapse on 3 March. Low-level tremor occurred from around 1900 on 2 March until 1444 on 3 March when seismicity increased significantly and an explosion and lava-dome collapse event lasting about 10 minutes occurred. According to the Washington VAAC, the ash cloud produced by the explosion reached a height of ~6 km a.s.l. During 1445-1500, pyroclastic flows swept NE down the Tar River, reaching the sea at the Tar River Fan at least twice. By 1525 seismicity had returned to background levels, although vigorous ash venting continued until around 0700 on 4 March. Low-level tremor began soon after the main event, lasting ~18 hours. Several hybrid earthquakes occurred during the evening of 3 March.

No ash fell in populated areas, rather it drifted SW over the southern parts of Plymouth, Amersham, and areas farther S. Visual observations suggested that the explosion removed the small lava dome that had grown in the collapse scar in late July 2003. A portion of the north-western remnant of the 1995-1998 lava dome also collapsed during the event. A small explosion on 5 March at 1009 was followed by ash venting. During the report period, the sulfur-dioxide flux reached a maximum value of 820 metric tons around 1 March, before falling to 540 metric tons on 2 March. As of 5 March seismic and volcanic activity remained at elevated levels.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC), Associated Press


25 February-2 March 2004

Volcanic and seismic activity remained at low levels at Soufrière Hills during 20-27 February. A period of low-level tremor began on 21 February around 0600 that continued for ~36 hours and consisted of many small long-period earthquakes. On 24 February around 0915 mudflows swept down the Belham valley (NW of the volcano) for ~40 minutes during intense rainfall. Signs of mudflows were also seen in the city of Plymouth (SW of the volcano). The sulfur-dioxide flux reached a peak daily value of 920 metric tons on 23 February.

Source: Montserrat Volcano Observatory (MVO)


18 February-24 February 2004

During 13-20 February, volcanic and seismic activity remained low at Soufrière Hills. The seismic network recorded one rockfall and three hybrid earthquakes. Sulfur-dioxide flux was at moderate levels, reaching between 350 and 650 metric tons per day.

Source: Montserrat Volcano Observatory (MVO)


11 February-17 February 2004

Volcanic and seismic activity at Soufrière Hills remained at low levels during 6-13 February. The seismic network recorded one volcano-tectonic earthquake and three hybrid earthquakes. Sulfur-dioxide flux was low and relatively constant at 350-450 metric tons per day.

Source: Montserrat Volcano Observatory (MVO)


4 February-10 February 2004

Volcanic and seismic activity at Soufrière Hills during 30 January to 6 February increased slightly in comparison to the previous week. The seismic network recorded 15 rockfalls, 1 volcano-tectonic earthquake, 7 long-period earthquakes, and 9 hybrid earthquakes. In addition, a weak long-period earthquake swarm began on 30 January. The swarm was comprised of ~1,000 separate events occurring over a ~30-hour period, although only four events were large enough to trigger the seismic-event detection systems. The sulfur-dioxide flux peaked on 1 February at 1,017 tons per day before decreasing to 439 tons on 5 February.

Source: Montserrat Volcano Observatory (MVO)


28 January-3 February 2004

Volcanism at Soufrière Hills remained at very low levels during 23-30 January. The seismic network recorded 8 rockfalls, 10 hybrid earthquakes, 1 volcano-tectonic earthquake, and 1 long-period earthquake. Sulfur-dioxide emissions were between 500 and 700 tons per day (no measurements were possible on 24 and 25 January).

Source: Montserrat Volcano Observatory (MVO)


21 January-27 January 2004

Activity at Soufrière Hills remained at low levels during 16-23 January, although there was a slight increase in seismic activity. The seismic network recorded 1 rockfall, 1 volcano-tectonic earthquake, and 38 long-period and 9 hybrid earthquakes. An unusual seismic event began on 18 January around 0600, consisting of a low-amplitude swarm of long-period earthquakes. The swarm continued for 36 hours and was comprised of ~1,000 separate events every ~2 minutes, although only 37 were large enough to trigger the seismic-event detection systems.

Source: Montserrat Volcano Observatory (MVO)


14 January-20 January 2004

Volcanic activity at Soufrière Hills remained at low levels during 9-16 January. The seismic network recorded 5 rockfalls and 1 long-period and 18 hybrid earthquakes. The sulfur-dioxide flux from the volcano was low at the beginning of the report period (less than 200 tons per day), increasing to around 350 tons per day after a minor ash-venting event on 9 January.

Source: Montserrat Volcano Observatory (MVO)


7 January-13 January 2004

Volcanic activity at Soufrière Hills remained low during 2-9 January, with low counts of all seismic signals. The seismic network recorded 2 rockfalls and 2 hybrid earthquakes. Sulfur-dioxide fluxes were also low and stable at around 300 tons per day.

Source: Montserrat Volcano Observatory (MVO)


31 December-6 January 2004

Volcanic activity at Soufrière Hills was low during 26 December to 2 January, with low counts of all seismic signals. The seismic network recorded 2 rockfalls, 9 hybrid earthquakes, and a swarm of small hybrid earthquakes during 31 December to 2 January. A sulfur-dioxide flux rate of 500 tons per day was measured at the beginning of the report period, but instrument problems and unfavorable wind directions hampered measurements during the rest of the week.

Source: Montserrat Volcano Observatory (MVO)


24 December-30 December 2003

Volcanic activity at Soufrière Hills remained low during 19-26 December, with low counts of all seismic signals. The seismic network recorded 1 rockfall and 2 hybrid earthquakes until 24 December.

Source: Montserrat Volcano Observatory (MVO)


17 December-23 December 2003

During 12-19 December, volcanic activity at Soufrière Hills was low, with few counts of all types of seismic signals. Only 2 rockfalls and 12 hybrid earthquakes were recorded. Sulfur-dioxide emissions remained fairly stable at around 500 tons per day during most of the week, but there was a significant increase to 3,600 tons on 18 December.

Source: Montserrat Volcano Observatory (MVO)


10 December-16 December 2003

Volcanic activity at Soufrière Hills was at low levels during 5-12 December, with low counts of all types of seismic signals. Visual observations confirmed that no new lava-dome growth occurred in the crater since July 2003, although some old lava-dome material from the crater walls had slumped and wall rocks had degraded due to steaming. Sulfur-dioxide flux measurements varied during the week from 800-900 tons per day at the beginning of the report period to 300-500 tons per day towards the end of the week.

Source: Montserrat Volcano Observatory (MVO)


26 November-2 December 2003

Volcanic activity at Soufrière Hills was lower during 21-28 November than during the previous week, with fewer hybrid earthquakes and low counts of other types of seismic signals. The seismic network recorded five rockfalls, one long-period earthquake, one volcano-tectonic earthquake, and 50 hybrid earthquakes. Around 500 tons of sulfur dioxide were recorded during the 2 days weather conditions were appropriate for measurements.

Source: Montserrat Volcano Observatory (MVO)


12 November-18 November 2003

During 7-14 November, volcanic activity at Soufrière Hills remained at low levels. The seismic network recorded three rockfall signals, one long-period earthquake, one long-period rockfall, and 36 hybrid earthquakes. Sulfur-dioxide emissions generally decreased from ~800 to ~200 tons per day during the report period.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


29 October-4 November 2003

Volcanic activity at Soufrière Hills during 24-31 October remained at low levels. No morphological changes were seen at the volcano's summit and no new lava was observed in the vent area. According to the Washington VAAC, on 1 November a low-level plume of re-suspended ash was visible on satellite imagery.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


22 October-28 October 2003

Volcanic activity at Soufrière Hills remained at low levels during 17-24 October. The lava dome was visible on 23 October when a volume survey was carried out. The small lava dome that extruded in July had not grown further, appearing to be stagnant with alteration and degradation causing it to break apart. The pit crater associated with the July 2003 explosions widened slightly, although MVO believes this is due to passive slumping of material rather than volcanic activity. Sulfur-dioxide emission rates remained high during the report week. Low-level ash clouds were sometimes visible on satellite imagery.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


15 October-21 October 2003

Activity at Soufrière Hills during 10-17 October remained at low levels. Seismicity indicated that 12 rockfalls occurred as well as nine hybrid earthquakes. Lahars were also noted during periods of heavy rainfall. Sulfur-dioxide emissions increased from 600-900 tons per day at the beginning of the week to a peak of 1,900 tons on 13 October, and descended to 720 tons on 16 October. Low-level ash plumes were occasionally seen on satellite imagery.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


8 October-14 October 2003

Volcanic activity at Soufrière Hills during 3-10 October was at a lower level than during the previous week. A period of low-amplitude tremor was recorded during 3-8 October that coincided with light ash venting. No direct views of the summit were possible due to poor visibility. Sulfur-dioxide emission rates were high during the week. Ash plumes were visible on satellite imagery.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


1 October-7 October 2003

Volcanic activity at Soufrière Hills during 26 September to 3 October was slightly higher than during the previous week. During 30 September to 1 October, tremor coincided with vigorous ash venting that produced clouds to between 2 and 2.5 km a.s.l. The ash clouds drifted W over the town of Plymouth. No new lava-dome growth was seen during the report week and sulfur-dioxide emission rates were generally at moderate-to-high levels.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


24 September-30 September 2003

Volcanic activity at Soufrière Hills remained at low levels during 19-26 September. Sulfur-dioxide emission rates were slightly lower than the previous week, ranging between 500 and 600 tons per day. According to the Washington VAAC, MVO reported that ash emissions on 30 September rose to a height of ~2.4 km a.s.l. and drifted W.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


17 September-23 September 2003

Volcanic activity at Soufrière Hills remained at low levels during 5-12 September. No new lava-dome growth occurred, although there were several ash-venting episodes that were accompanied by a few small earthquakes. Sulfur-dioxide emission rates were relatively low during the report week.

Source: Montserrat Volcano Observatory (MVO)


10 September-16 September 2003

Volcanic activity at Soufrière Hills remained at low levels during 5-12 September. No new lava-dome growth occurred, although there were several ash-venting episodes that were accompanied by a few small earthquakes. Sulfur-dioxide emission rates were relatively low during the report week.

Source: Montserrat Volcano Observatory (MVO)


3 September-9 September 2003

Activity at Soufrière Hills remained at low levels during 29 August to 5 September. No growth occurred at the new lava dome. During the later part of the week gas emission rates could not be measured because the plume was blown out of reach of the spectrometer in unusual wind directions caused by Hurricane Fabian.

Source: Montserrat Volcano Observatory (MVO)


27 August-2 September 2003

Activity at Soufrière Hills remained at low levels during 22-29 August. No changes or growth occurred at the lava dome. Small changes occurred in the 12 July collapse scar, with new fumaroles opening to the SE of the main explosion crater towards the upper Tar River Valley. Blue haze visible N of the volcano on 25 August and a strong sulfur smell were caused by the passage of a weather system and did not reflect an activity increase.

Source: Montserrat Volcano Observatory (MVO)


20 August-26 August 2003

Volcanic and seismic activity at Soufrière Hills remained at relatively low levels during 15-22 August. Views of the lava dome inside the explosion crater showed that no further growth had occurred. Some very small rockfalls were produced from the interior of the 12 July collapse scar, and in several places large fumaroles formed. Sulphur-dioxide emissions ranged from 400 to 900 tonnes per day, with the maximum being recorded on 18 August.

Source: Montserrat Volcano Observatory (MVO)


13 August-19 August 2003

Volcanic activity at Soufrière Hills was at low levels during 8-15 August. Views of the new lava dome indicated that no further growth had taken place; it remained a small lobe over 100 m across. Several small slumps occurred from the interior wall of the 12 July scar, producing rockfalls and a small amount of ash in the plume. Sulfur-dioxide emissions were generally high during the week, with maximum emission rates on 11-12 August.

Source: Montserrat Volcano Observatory (MVO)


6 August-12 August 2003

During 25 July to 1 August, volcanic activity at Soufrière Hills was low, with only a few seismic events triggering the network. Activity increased at the end of the report week, on 1 August, with episodes of powerful ash venting from the explosion crater. There were many strong bursts of gas and jets of ash; an ash plume rose to over 3 km. During 1-8 August, activity fluctuated, with a period of relative quiet separating episodes of intense degassing and hybrid-earthquake activity. Occasional rockfalls and hybrid earthquakes occurred during most of the report week. The lava dome was visible on 5 August; there was a small southerly-directed lobe in the dome that was growing extremely slowly, if at all. Sulfur-dioxide emission rates were high for most of the report week.

Source: Washington Volcanic Ash Advisory Center (VAAC)


30 July-5 August 2003

As of 1 August, ash emissions were continuing from Soufrière Hills. Low-level ash clouds were visible on satellite imagery.

Source: Washington Volcanic Ash Advisory Center (VAAC)


23 July-29 July 2003

During 18-25 July, volcanic and seismic activity at Soufrière Hills were at very low levels, with only a few events triggering the seismic network. The pattern of earthquakes during the week indicated that lava-dome growth within the explosion crater had probably restarted, although this could not be confirmed because Soufrière Hills was obscured by low-level meteorological clouds. Sulfur-dioxide flux declined somewhat in comparison to the previous week.

Source: Montserrat Volcano Observatory (MVO)


16 July-22 July 2003

After a lava-dome collapse at Soufrière Hills on 12 July volcanic activity was at relatively high levels until 13 July when it slowly subsided. On the 13th activity had declined to very low levels, then the following morning a sudden vulcanian explosion occurred at the lava dome. Two more explosions occurred during the next 2 days. Pumice from these explosions reached 15 cm in size at Richmond Hill, declining to 4 cm in Olveston. Heavy ashfall from the collapse occurred over all the inhabited parts of Montserrat. The greatest ash thickness was recorded at the Vue Pointe Hotel, where it exceeded 15 cm in depth. After an explosion on 15 July, volcanic and seismic activity were relatively low, with only a few hybrid earthquakes and rockfalls each day. Scientists saw an open explosion crater in the collapse scar, with no new lava extruded. The bulk of the lava-dome structure was removed during the collapse. Pyroclastic flows impacted the area between Tar River Valley and Spanish Point.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


9 July-15 July 2003

High levels of pyroclastic-flow activity began at Soufriere Hills on 12 July. A hybrid earthquake swarm that began on 9 July merged at 0700 on 12 July into a continuous tremor signal. Prolonged and heavy rainfall occurred on the 12th during 0600-0900, causing mudflows into the Belham Valley. Pyroclastic flows began to travel into the Tar River Valley, with a moderate-sized flow occurring at 0653. A series of similar-sized pyroclastic flows traveled in the Tar River Valley throughout the morning. The first pyroclastic flow reached the sea at 1045. Pyroclastic-flow activity increased slowly through the afternoon until it became almost continuous. Flows also occurred into Tuitt's and White's ghauts. The activity picked up markedly at 1827, with more energetic pyroclastic flows. The level of activity fluctuated thereafter, with several smaller pyroclastic flows into the Tar River Valley, before escalating again at 2005 with another phase of near-continuous pyroclastic flows. The flows increased in size and several surges traveled 2 km over the sea at the mouth of the Tar River Valley. Pyroclastic flows also reached the sea in White's Ghaut and the Spanish Point area. These flows resulted in heavy ashfall and accretionary lapilli, particularly between Salem and Woodlands. A number of explosive events took place during this collapse, with the largest occurring between 2300 and 2400. The Washington VAAC reported that ash clouds rose to a maximum height of ~15 km a.s.l.

Heavy falls of ash and rock fragments occurred over all of the inhabited parts of Montserrat. The ashfall deposit was 115 mm thick at Lime Kiln Bay. The ash burden resulted in the collapse of several wooden buildings in the Salem area. Vegetation damage was extensive with downed trees and branches broken from many others. Many birds were killed by the ash or trapped alive in it. Ashfall from this event was reported on the islands of Nevis, St Kitts, Anguilla, and St Maarten, and resulted in the closure of several airports. At 0910 on 13 July an explosive eruption occurred, following 2 hours of very low seismic activity. The Washington VAAC estimated a cloud height of ~12 km a.s.l.

During a helicopter reconnaissance flight on the morning of 14 July, a large collapse scar was seen in the lava dome directed down the Tar River Valley. The Tar River Valley was extensively modified and eroded with a deep canyon gouged by the pyroclastic flows. The fan had been extended eastwards into the sea and northwards along the coast. The area north of the Tar River Valley extending to Killyhawk Ghaut was devastated.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC), Associated Press, Reuters


2 July-8 July 2003

During 27 June- 4 July, activity at Soufrière Hills increased in comparison to the previous week. Pyroclastic flows and rockfalls mainly traveled down the lava dome's N flank, mostly into Tuitt's Ghaut and to a lesser extent into Tyre's and White's ghauts. Sporadic pyroclastic flows also traveled W to the Gages area. The sulfur-dioxide emission rate was relatively low during the week.

Source: Montserrat Volcano Observatory (MVO)


25 June-1 July 2003

Volcanic and seismic activity at Soufrière Hills remained at low levels during 20-26 June, but increased on 27 June. There were no apparent changes at the summit region since it was last observed several weeks previously. During 20-25 June, rockfalls and sporadic pyroclastic flows occurred on the lava dome's E and N flanks and traveled into the Tar River Valley, and White's, Tuitt's, and Tyre's ghauts. Hybrid earthquake activity developed into a diffuse swarm on 22 and 23 June. Some of the larger hybrid earthquakes were located at depths of about 3 km beneath the lava dome. On 27 June activity was mainly confined to the northern flanks with numerous small pyroclastic flows into Tuitt's and Tyre's ghauts.

Source: Montserrat Volcano Observatory (MVO)


18 June-24 June 2003

Volcanic and seismic activity remained at low levels during 13-20 June. Small rockfalls and sporadic pyroclastic flows traveled down the E and N flanks of the lava dome into the Tar River Valley, White's Ghaut, and the top of Tuitt's Ghaut. Sulfur-dioxide emission rates were relatively low during the first half of the report period, increasing slightly during the middle of the week.

Source: Montserrat Volcano Observatory (MVO)


11 June-17 June 2003

Volcanic activity at Soufrière Hills decreased to low levels during 6-13 June, with sporadic rockfalls and pyroclastic flows traveling down the volcano's E and NE flanks to the Tar River Valley, and White's and Tuitt's ghauts. Several energetic pyroclastic flows occurred in the Tar River Valley in the early hours of 11 June and again on the morning of 13 June.

Source: Montserrat Volcano Observatory (MVO)


4 June-10 June 2003

Volcanic activity at Soufrière Hills generally declined to moderate-to-low levels during 30 May to 6 June. Most activity was focused on the E and NE flanks of the lava dome, producing rockfalls and numerous pyroclastic flows in the Tar River Valley and occasionally in White's and Tuitt's ghauts. On the morning of 3 June activity briefly increased on the lava dome's NW flank, when numerous rockfalls and three pyroclastic flows entered Tyre's Ghaut. Sulfur-dioxide emission rates in the volcanic plume were moderate, averaging 540 tons per day, which is very similar to the long-term average for the entire eruption. Low-level ash plumes were sometimes visible on satellite imagery.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


28 May-3 June 2003

Volcanic activity at Soufrière Hills decreased slightly during 23-30 May. Most activity was focused on the lava dome's ENE flank, producing rockfalls and numerous pyroclastic flows along the N side of the Tar River Valley and occasionally in White's and Tuitt's ghauts. Rockfalls and small pyroclastic flows also spilled off the lava dome's northern flanks onto Farrell's Plain. The lava dome began to grow more centrally, building vertically upwards and accumulating debris on the summit region. The sulfur dioxide emission rate was approximately average at the beginning of the week, but increased towards the middle of the week. Small low-level ash plumes were occasionally visible on satellite imagery.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


21 May-27 May 2003

Volcanic activity at Soufrière Hills was generally at high levels during 16-23 May, although there was a slight decrease in intensity on 19 and 20 May. Most activity was focused on the lava dome's NE flank, producing rockfalls and numerous pyroclastic flows along the northern side of Tar River Valley. During the last 3 days of the report period, activity increased on the N flank, with pyroclastic flows traveling into the top of Farrell's Plain and entering the top of Tyre's and Tuitt's ghauts. Pulses of vigorous ash venting were observed from the dome's summit. Intense glow was seen on the summit and NE flank on the evenings of 20 and 21 May. Low-level ash plumes were sometimes visible on satellite imagery.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


14 May-20 May 2003

Activity at Soufrière Hills remained high during 9-16 May. The direction of lava-dome growth switched to the NE during the report period. Rockfalls and pyroclastic flows travelled NE along the N side of the Tar River Valley and occasionally occurred in White's Ghaut. On 12 and 13 May several flows were observed on the lava dome's N and NW flanks in the area of Farrell's Plain and in the upper portions of Tyre's Ghaut. Pulses of vigorous ash venting were observed. SO2 emission rates fluctuated from moderate-to-high levels. The Washington VAAC reported that low-level ash plumes were sometimes visible on satellite imagery.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


7 May-13 May 2003

During 25 April to about 6 May, volcanic activity was at moderate levels at Soufrière Hills, with pyroclastic flows and rockfalls mainly traveling NE. During about 6-9 May there was a general increase in the size of pyroclastic flows, some of which were among the largest and most energetic seen for several months. Most flowed along the N side of the Tar River Valley, and a few also flowed into White's and Tuitt's ghauts. Sulfur-dioxide emission rates were low during about the first week of the report period, then fluctuated from moderate to high levels. The Washington VAAC reported that low-level ash plumes were sometimes visible on satellite imagery.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


16 April-22 April 2003

During 16-22 April, dome extrusion continued at Soufrière Hills. Poor visibility prevailed for parts of the week, but seismicity and SO2 fluxes remained significant. Numerous rockfalls and pyroclastic flows have occurred on the eastern flanks of the dome in the Tar River Valley. An observation flight indicated that rockfalls were beginning to spill southwards into the head of the White River. Observers noted that a very large spine had extruded on the dome=s summit. Despite frequent cloud cover during the week, satellite infrared sensors sometimes detected the thermal radiation from the dome, and other sensors continued to detect plumes from the volcano, typically tens of kilometers in length and blowing W.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


9 April-15 April 2003

Activity at Soufrière Hills was generally at moderate levels during 4-11 April, although there were short periods of more elevated activity. Rockfalls and pyroclastic flows mainly occurred on the E side of the lava dome in the Tar River Valley. Pyroclastic flows were also observed on the NE flank in White's and Tuitt's ghauts. Torrential rainfall late in the evening of 10 April produced mudflows in the Belham River and triggered pyroclastic flows on the E, N, and NW flanks of the lava dome. The Washington VAAC reported that low-level ash plumes were sometimes visible on satellite imagery.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


2 April-8 April 2003

Volcanic activity at Soufrière Hills increased slightly during 28 March to 4 April and for the last 2 days of the report period activity was at moderately high levels. A prominent extrusion lobe was established on the E and SE sides of the lava dome's summit. A large vertical spine was extruded at the back of this lobe during the night of 1-2 April. During the report week, activity was dominated by rockfalls and pyroclastic flows mainly in the Tar River Valley. Rockfall activity also continued on the dome's S side. Some pyroclastic flows also occurred on the NE flanks in White's Ghaut and Tuitt's Ghaut, and on most days rockfalls and small pyroclastic flows initiated on the NW flanks, often moving into the upper reaches of Tyre's Ghaut. Sulfur dioxide emission rates fluctuated during the report period. The Washington VAAC reported that low-level ash plumes were sometimes visible on satellite imagery.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


26 March-1 April 2003

Activity at Soufrière Hills during 21-28 March remained at moderate levels. A lava dome continued to grow centrally from its summit region. Activity was dominated by rockfalls and pyroclastic flows that spilled off the active summit in a broad arc extending from the S and around the E flanks to the NW. Most activity was towards the NW, with pyroclastic flows occurring in the Tar River Valley. Small pyroclastic flows also traveled down the dome's N flank into White's Ghaut, Tuitt's Ghaut, the upper reaches of Tyre's Ghaut, and on Farrell's Plain. After a brief, intense rainstorm there was a 4- to 5-hour-long period of increased pyroclastic-flow and rockfall activity. Observations on 27 and 28 March revealed that rockfalls and small pyroclastic flows had begun to spill off the dome's S flank and a large vertical spine had extruded on the S side of the summit. Sulfur dioxide emission rates fluctuated considerably during the report week. The Washington VAAC reported that low-level ash plumes were visible on satellite imagery.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


19 March-25 March 2003

Volcanic and seismic activity at Soufrière Hills remained at moderate levels, as they have for several weeks. Lava-dome growth continued near the center of the dome complex, where a series of spines and ridges formed. The dome's summit reached a height of 1,098 m, the highest measured thus far. Activity was dominated by rockfalls and pyroclastic flows originating from the NE/central region of the dome that mainly traveled to the Tar River Valley. Also, several small pyroclastic flows occurred in White's and Tuitt's Ghauts, and one was observed in the upper part of Tyre's Ghaut on 20 March. Ash venting continued from the active part of the lava dome. The Washington VAAC reported that low-level ash plumes were visible on satellite imagery.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


12 March-18 March 2003

During 7-14 March, volcanic and seismic activity at Soufrière Hills were at moderate levels that were similar to those of the previous 2 weeks. The lava dome continued to grow, but was not focused in any particular direction. Lava extruded into the center of the summit-dome complex, increasing the dome height to just over 1,100 m. Rockfalls and pyroclastic flows occurred down all of the volcano's flanks. Spectacular incandescence was visible at night in the Tar River Valley, NW in Tuitt's Ghaut, and on the N talus slopes. Small rockfalls and pyroclastic flows infrequently descended the volcano's W flank, to the top of Gage's Valley. Ash vented continuously in the dome summit area and sulfur dioxide emission rates were relatively low during the week. The Washington VAAC reported that several low-level ash plumes were visible on satellite imagery.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


5 March-11 March 2003

During 28 February to 7 March, volcanic activity at Soufrière Hills remained at similar levels to the previous few weeks, with continued lava-dome growth and moderate pyroclastic-flow activity. Lava extrusion was accompanied by rockfalls and pyroclastic flows to the NE and N talus slopes and valleys. Pyroclastic flows occurred most frequently in Tuitt's Ghaut, and a few on Farrell's Plain, with run-out distances up to 1 km. Sulfur dioxide emission rates were variable. The Washington VAAC stated that several low-level ash plumes were visible on satellite imagery.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


26 February-4 March 2003

Activity at Soufrière Hills increased slightly during 21-28 February in comparison to the previous week. During an observation flight on 27 February, scientists saw that lava-dome growth was concentrated towards the NE. Pyroclastic flows and rockfalls traveled down the lava dome's E and NE flanks via the Tar River Valley and Tuitt's Ghaut. There were also several periods of activity on the N flank, with pyroclastic flows at the top of Farrell's Plain. SO2 emission rates were moderate for much of the report period, with the exception of 22-23 February, when rates increased. The Washington VAAC stated that several low-level ash plumes were visible on satellite imagery.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


19 February-25 February 2003

Activity at Soufrière Hills remained at moderate levels during 14-21 February. Remote camera footage indicated continued lava-dome growth on the NE lobe. Pyroclastic flows and rockfalls were concentrated more on the E flank of the lava dome and in the Tar River Valley than in recent weeks, although there were several periods of activity on the N flank, with pyroclastic flows in Tuitt's Ghaut and at the top of Farrell's Plain. SO2 emission rates were at low-to-moderate levels. The Washington VAAC stated that several low-level ash plumes were visible on satellite imagery.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


12 February-18 February 2003

Activity at Soufrière Hills was at moderate levels during 7-14 February. Lava-dome growth was focused towards the NNE and produced pyroclastic flows and rockfalls in Tuitt's Ghaut, White's Ghaut, and along the N side of the Tar River Valley. Rockfalls and small pyroclastic flows also occurred off the N flank of the dome onto the area of Riley's Estate. The Washington VAAC stated that several low-level ash plumes were visible on satellite imagery.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


5 February-11 February 2003

Activity at Soufrière Hills remained at moderate levels during 31 January to 7 February. Growth of the lava dome was focused on a large, steep lobe directed to the NE. Continuous growth and failure of the lobe produced pyroclastic flows and rockfalls in Tuitt's Ghaut, White's Ghaut, and along the N side of the Tar River Valley. A small amount of rockfall material was directed W towards Fort Ghaut. SO2 emission rates were slightly lower than the previous week. The Washington VAAC stated that several low-level ash plumes were visible on satellite imagery.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


29 January-4 February 2003

Activity at Soufrière Hills was at moderate levels at the beginning of the report period (24-31 January), but increased late in the evening of 25 January and remained high for the remainder of the week. Growth of the active extrusion lobe continued on the N side of the lava dome. The direction of growth was generally towards the NNE, although the focus of rockfall and pyroclastic-flow activity varied from day to day. Numerous small-to-moderate pyroclastic flows occurred in White's Ghaut, the Tar River Valley, and Tuitt's Ghaut. A pulse of activity occurred at midday on 30 January, during which pyroclastic flows simultaneously descended several flanks of the lava dome traveling to the Tar River Valley, White's Ghaut, Tuitt's Ghaut and W to Fort Ghaut. SO2 emission rates fluctuated throughout the week. The Washington VAAC stated that several low-level ash plumes were visible on satellite imagery.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


22 January-28 January 2003

Volcanic and seismic activity were at moderate levels at Soufrière Hills during 17-24 January. Lava extrusion occurred NE of the lava-dome complex that was associated with rockfalls and small pyroclastic flows down Tar River Valley, White's Ghaut, Tuitt's Ghaut, and on the northern talus slopes. On 18, 20, and 24 January small pyroclastic flows traveled ~ 1 km down Tyer's Ghaut. SO2 emission rates were moderate throughout the week. The Washington VAAC stated that several low-level ash plumes were visible on satellite imagery.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


15 January-21 January 2003

The level of activity at Soufrière Hills fluctuated during 10-17 January, but generally declined from high to moderate levels. The active extrusive lobe on the lava dome's N side continued to grow, producing pyroclastic flows and rockfalls during the first days of the report period down White's Ghaut and the Tar River Valley, and to a lesser extent to Tuitt's Ghaut and the top of Tyre's Ghaut and Farrell's Plain. During 15-17 January almost all pyroclastic flows occurred in the Tar River Valley, with only minor rockfalls traveling down the dome's NE and N sides. SO2 emission rates were variable, with periods of heightened emission lasting a few hours followed by very low levels of emission. The Washington VAAC stated that several low-level ash plumes were visible on satellite imagery.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


8 January-14 January 2003

Activity at Soufrière Hills during 3-10 January remained at high levels. The active extruded lobe on the lava dome continued to grow mainly towards the NNE, although some growth also occurred on the N side of the summit region. Rockfalls and small-to-moderate pyroclastic flows spilled off of the active lobe mostly into White's Ghaut and to a lesser extent into Tuitt's Ghaut and the Tar River Valley. Pyroclastic flows and rockfalls also spilled off the domes's N and NW flanks onto Farrell's Plain and into Tyre's Ghaut. During the report week, the Washington VAAC stated that several low-level ash plumes were visible on satellite imagery.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


31 December-6 January 2003

Activity at Soufrière Hills was at high-to-very-high levels during most of 27 December to 3 January, but decreased during 3 January. Activity escalated to very high levels on the night of the 27th. For the first 5 days of the report period continuous rockfalls and numerous pyroclastic flows spalled off the active extruded lobe on the NNE side of the lava dome. Most of the pyroclastic flows occurred in White's Ghaut and the Tar River Valley, and to a lesser extent in Tuitt's Ghaut. Small flows and rockfalls also spilled off the N and NW flanks of the dome onto Farrell's Plain and into Tyre's Ghaut. Activity decreased considerably on the night of 2 January to moderate levels on the 3rd, with rockfalls and small pyroclastic flows confined to the NNE and to a lesser extent the N flanks of the dome. The large spine that grew on the summit at the end of the previous week was observed on several days at the beginning of the current reporting period, but was not present when the summit was next seen on 2 January.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


24 December-30 December 2002

Activity at Soufrière Hills during 20-27 December remained at high levels. The active extruded lobe on the N side of the lava dome continued to grow, giving rise to rockfalls and small-to-moderate pyroclastic flows across a broad sector of the NE and N flanks. Spectacular incandescence was observed on most nights. Growth was focused mainly towards the NNE, producing pyroclastic flows in White's Ghaut, the Tar River Valley, and Tuitt's Ghaut. Extrusion also occurred on the N side of the summit and occasionally on the NW. A large spine was pushed up at the back of the active extruded lobe during the night of 26-27 December. The Washington VAAC reported that on 28 December around 1130 a 3-km-high ash cloud generated from pyroclastic flows drifted over the islands of St. Kitts and Nevis.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


18 December-24 December 2002

Volcanic activity at Soufrière Hills increased to a high level during 13-20 December. Activity generally remained at moderate levels during the first half of the report period, but increased to a high level over the last 3 days. Spectacular incandescence of the dome was observed on most nights. The active extruded lobe on the dome's N side continued to grow, producing numerous rockfalls and small-to-moderate pyroclastic flows. Most of the activity was concentrated on the NNE and N flanks, producing numerous pyroclastic flows in White's Ghaut, the Tar River Valley and Tuitt's Ghaut. Pyroclastic flows and rockfalls also traveled down the W and NW flanks. On 19 December mudflows occurred in White River, Tar River Valley and Fort Ghaut.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


11 December-17 December 2002

Reports of activity at Soufrière Hills covered the interval 6-13 December. Activity increased during the first 3 days of this interval, peaking in a dome-collapse event on the night of 8 December. Following this event, activity returned to moderate levels for the remainder of the week.

On 6 and 7 December most activity occurred on the N and NE flanks of the active extruded lobe, producing numerous pyroclastic flows in Tuitt's and White's ghauts, and the Tar River Valley. On 8 December, activity was focused NNE, producing numerous small-to-moderate pyroclastic flows in White's Ghaut. A sustained dome collapse began on 8 December at 2045, producing energetic pyroclastic flows down White's Ghaut to the sea at Spanish Point. Ash clouds rose to ~3 km a.s.l. and drifted WNW. In Plymouth and Richmond Hill 4 mm of ash was deposited. Seismic activity returned to background levels on 9 December by 0045 and several days of weak tremor occurred.

The collapse scar formed on the dome's NNE flank was estimated to have had a volume of 4-5 million cubic meters. This was being filled rapidly with freshly extruded lava. Observations on 13 December revealed a large amount of fragmental lava extruded in a northerly direction on the summit. A large spine was also extruded on the NW side of the summit.

SO2 emission rates were generally low during the first 3 days of the report period (280 metric tons per day on average), but following the dome-collapse event, on 9 December, they reached an average of 2,350 tons per day. On 10 December emission rates decreased to an average of 620 tons per day.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


4 December-10 December 2002

Activity at Soufrière Hills during 29 November to 6 December remained at moderate levels. Growth of the active lava dome in the N part of the dome complex continued. A number of small, short-lived spines formed at the base of this lobe, shedding material E into White's Ghaut and the Tar River Valley. Lava blocks continued to spall off the front of the lobe, shedding material NE into Tuitt's Ghaut and onto the northern talus slope. An average of one moderate-sized pyroclastic flow occurred per day during the report week. They traveled no farther than 1-1.5 km from the lava dome into Tuitt's and White's ghauts and into the Tar River Valley. During 5-6 December, rockfalls and small pyroclastic flows occurred more frequently on the northern talus slope and on the NW, at the top of Tyer's Ghaut.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


27 November-3 December 2002

Volcanic and seismic activity at Soufrière Hills remained at moderate levels during 22-29 November. Growth of the active extruded lobe on the N side of the lava dome continued to produce rockfalls and small-to-moderate pyroclastic flows. Pyroclastic-flow activity was confined mainly to Tuitt's and White's Bottom ghauts, and also along the N edge of the Tar River Valley. On 29 November the active lobe had a broad whaleback-shaped upper surface, which was oriented towards the NNE. SO2 emission rates were generally high.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


20 November-26 November 2002

Activity at Soufrière Hills remained moderate during 15-22 November. The lava dome was not visible during the week due to cloudy conditions. Rockfalls and small pyroclastic flows were concentrated on the volcano's E and NE flanks. During the 15th to 19th, small pyroclastic flows traveled 1-1.5 km from the dome every few hours in Tuitt's Ghaut to the NE and in the Tar River Valley to the E. On 9 November small pyroclastic flows traveled down the Tar River Valley. Rockfalls continued to occur on the NW flank of the lava dome throughout the report period. SO2 emission rates were relatively low.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


13 November-19 November 2002

Activity at Soufrière Hills increased slightly during 8-15 November. On the 8th and 9th pyroclastic flows traveled 900-1,000 m NW into Tyer's Ghaut at the headwaters of the Belham Valley. From the 10th to 15th, lava-dome growth and ash venting were concentrated to the NE at the base of the NW lava lobe. Rockfall and pyroclastic-flow debris were shed predominantly NE down Tar River Valley and Tuitt's Ghaut and occasionally down the NW flank. During the last 3 days of the report period, the size and energy of the pyroclastic flows increased slightly. SO2 emission rates were higher than the previous week, with a mean emission rate of 520-560 tons per day.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


6 November-12 November 2002

Volcanic activity at Soufrière Hills during 1-8 November was at similar levels to the past few weeks. Lava-dome growth on the N part of the dome continued through the report period, although it was less directed, with rockfalls dispersed over the summit and flanks. The lobe shed rockfall debris predominately down Tuitt's Ghaut and Tar River Valley, although also onto the NW flank and into the top of Gage's Valley. SO2 emission rates were generally low throughout the week, with a peak on 4 November. According to the Washington VAAC, on the 8th strong pyroclastic flows produced ash-and-gas clouds to a height of ~1.5 km.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


30 October-5 November 2002

Activity at Soufrière Hills during 25 October to 1 November generally increased in comparison to the previous week. The volcano was observed using a remote camera and during a flight on 31 October. The active extruded lobe in the NW continued to steadily grow, bulking out on the N and W sides. Rockfalls and pyroclastic flows traveled down the E and N flanks, particularly within Tuitt's Ghaut and the Tar River Valley. A considerable amount of debris also spalled off the W flank of the active extruded lobe and accumulated in the upper parts of Fort Ghaut. SO2 emission rates were low throughout the week.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


23 October-29 October 2002

Volcanic and seismic activity at Soufrière Hills remained at a similar level during 18-25 October to that of the previous week. Occasional clear views of the lava dome revealed that the active extrusion lobe in the NW continued to grow steadily, increasing in height and bulging out on the N and W sides. The most notable event of the week occurred on the afternoon of 22 October when intense rainfall at midday produced large mudflows NW in the Belham Valley where residents had recently been evacuated. At the peak of flow, the entire width of the valley floor at Belham Bridge was flooded and standing waves up to 2.5 m high were observed. By 1430, pyroclastic-flow activity began. For several hours, pyroclastic flows were generated off of the N flank of the dome and were channeled northeastwards into the upper parts of Tuitt's Ghaut, from where they crossed over into White's Bottom Ghaut. Flows also occurred on the dome's E flank in the Tar River Valley. SO2 emission rates were low at the beginning of the report period and increased towards the end of the week.

Sources: Montserrat Volcano Observatory (MVO), Associated Press


16 October-22 October 2002

Volcanic and seismic activity at Soufrière Hills remained at moderate levels during 11-18 October. Signals associated with rockfalls and pyroclastic flows continued to dominate the seismicity. The NW extrusion lobe of the lava dome continued to grow steadily. Growth remained centralized and there was noticeable bulking up of the lobe's summit area. Rockfalls and small pyroclastic flows traveled mainly down the northern flanks of the volcano, although some also traveled E into the incised channel on the N side of the Tar River Valley, and W into the upper portions of Fort Ghaut. Talus continued to accumulate behind the NW buttress and in the head of Tyre's Ghaut. SO2 emission rates varied considerably during the report period.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


9 October-15 October 2002

During 4-11 October, volcanic and seismic activity at Soufrière Hills remained at moderate levels. The NW extrusion lobe of the lava dome continued to grow steadily; early in the report period it grew to the NW, but later growth was more centralized. There was a noticeable bulking up of the summit area of the lobe. Rockfalls and small pyroclastic flows were shed into the upper portions of Fort Ghaut and Tuitt's Ghaut. Minor mudflow activity occurred during the evening of the 9th. The growth of the lava dome towards the NW increased the probability of pyroclastic flows entering the Belham River system. In order to reduce the level of risk this poses, populated areas along the fringes of the lower part of the Belham Valley (~300 people) were evacuated on 8 and 9 October, and were declared part of the Exclusion Zone. A relatively small pyroclastic flow traveled NNE down the flanks of the volcano on the 13th.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC), Associated Press


2 October-8 October 2002

Volcanic and seismic activity at Soufrière Hills increased significantly during 26 September to 4 October following the previous week's major switch in lava-dome extrusion direction. On the 27th a 4-hour-period of heightened activity occurred in the afternoon and evening, with small semi-continuous pyroclastic flows traveling down the N flanks and eastwards into the upper portions of Tuitts Ghaut and then into Whites Bottom Ghaut. A newly extruded lobe was visible on the 28th almost directly to the NW with a broad headwall over the N, NW, and W flanks. On the evening of the 29th there was another period of heightened activity on the northern flanks that lasted 1.5 hours, with pyroclastic flows just reaching the sea along Whites Bottom Ghaut. It was estimated that during this small event only 2-3 million m3 of the N edge of the active NW lobe was shed. Observations on 1 October revealed that re-growth of the collapsed area had occurred. A brief period of heavy rain on the 2nd triggered a moderate-sized mudflow down the Belham Valley. Analysis of seismic data suggested that pyroclastic-flow activity on the 2nd began at 13:10 and sustained dome collapse continued for 6 hours. Low-energy pyroclastic flows were observed reaching the sea on the Tar River's flanks throughout the collapse, and ash clouds were produced that drifted to the NW. Heavy ashfall occurred in the residential areas of Salem, Old Towne, and Olveston, with deposits up to 9 mm thick. Subsequent observations revealed that this collapse was confined to the volcano's eastern flanks, and that this was again a relatively small event (less than 5 million m3 of material was shed off of the eastern side of the dome complex).

According to the Washington VAAC, after daybreak on 3 October there were several reports of ashfall in Puerto Rico, and visible satellite imagery at 1115 confirmed that an ash cloud at a height of around 2.4 km a.s.l. covered most of the island. At 1615 the area of very thin ash was not visible on satellite imagery. By the next day, ash from the previous day's emissions had drifted W and around 0902 it was located over southern Puerto Rico nearest to the city of Ponce. A thin plume of ash also extended SSW of St. Croix island.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


25 September-1 October 2002

During 20-27 September, activity at Soufrière Hills' dome complex increased in comparison to the previous week, with a major change in direction of extrusion following a hybrid earthquake swarm the previous week. Growth of the previously active NE lobe stagnated during the 21st to 22nd. A near vertical spine was extruded in the central area around the 21st, possibly indicating a switch in growth direction. Observations on the 26th revealed a large new lobe that had extruded towards the W in the area previously known as Gages Wall. Material spalling off of this lobe produced rockfalls and small pyroclastic flows down Gages Valley for up to 1 km. The most notable events were pyroclastic flows on the evening of the 25th and the morning of the 27th. Growth and rockfall activity then changed towards the northern flanks, suggesting a possible stagnation of the recently extruded western lobe. Spectacular incandescence and semi-continuous rockfall activity were observed on the NE and N flanks of the dome on the night of the 26th and the early hours of the 27th. The Washington VAAC reported that a low-level ash cloud from an emission on the 29th at 1510 was visible over E Puerto Rico on satellite imagery through the following day. On the 30th a light dusting of white ash fell in E Puerto Rico at Roosevelt Roads Naval Air Station.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


18 September-24 September 2002

During 13-20 September, activity at Soufrière Hills increased in comparison to the previous week. Lava-dome growth was directed to the NE, with frequent rockfalls and small pyroclastic flows sending material to a sector extending from the central Tar Valley on the E flank to the NE flanks above Tuitt's Ghaut. Some material tumbled down a notch onto the northern flank. SO2 flux remained at low-to-moderate levels when recorded during the beginning of the report week. Low-level ash-and-steam clouds were sometimes visible on satellite imagery.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


11 September-17 September 2002

During 6-13 September, activity at Soufrière Hills remained at moderate levels. Growth on the lava-dome complex remained centralized on the E flank, with frequent rockfalls and small pyroclastic flows. At the beginning of the week most of these spilled eastward along the N side of the Tar River Valley, but later in the week activity appeared to refocus northward onto Tuitt's Ghaut. SO2 flux remained at moderate levels. On 11 September a faint ash plume was visible on satellite imagery.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


4 September-10 September 2002

Volcanic and seismic activity remained at moderate levels at Soufrière Hills during 30 August-6 September, although there was an increase in activity in comparison to the previous week. Lava-dome growth continued to be focussed on the N side of the dome complex although it became more centralized. The summit height exceeded 1,050 m. Frequent rockfalls and small pyroclastic flows travelled down the volcano's NE flank. Most were channeled into the upper portions of Tuitt's Ghaut, although some spilled eastward along the northern side of the Tar River Valley. SO2 flux remained at low-to-moderate levels.

Source: Montserrat Volcano Observatory (MVO)


28 August-3 September 2002

During 23-30 August, volcanic and seismic activity at Soufrière Hills remained at moderate levels. Small pyroclastic flows traveled mainly down the NE flank where they were channeled into the upper portions of Tuitt's Ghaut, although some spilled eastwards along the northern side of the Tar River Valley. Talus also continued to accumulate in the notch in the NW sector of the old lava dome, which leads towards Tyre's Ghaut. SO2 flux remained at moderate levels.

Source: Montserrat Volcano Observatory (MVO)


21 August-27 August 2002

Volcanic and seismic activity at Soufrière Hills were at moderate levels during 16-23 August. Lava-dome growth continued to be focused on the N side of the dome complex and rockfall talus continued to accumulate to the N in the upper reaches of Tuitt's Ghaut. In addition, there were overspills of talus from the northern side of the Tar River Valley into the two tributaries of White's Ghaut. Talus also slowly accumulated in the notch in the NW sector of the old dome that leads towards Tyre's Ghaut. During intense rainfall in the early hours of Wednesday morning, a small collapse occurred in the Tar River Valley. SO2 flux remained at moderate levels.

Source: Montserrat Volcano Observatory (MVO)


14 August-20 August 2002

Volcanic and seismic activity at Soufrière Hills remained at high levels during 9-16 August. Lava-dome growth remained focused on the N side of the dome complex. Rockfall talus accumulated in the upper portions of Tuitt's Ghaut, and small pyroclastic flows occurred to the N in both Tuitt's and White's ghauts. The active lobe also shed rockfall talus into the notch in the north-western sector of the old dome which leads towards Tyre's Ghaut. SO2 fluxes remained at moderate levels.

Source: Montserrat Volcano Observatory (MVO)


7 August-13 August 2002

During 2-9 August, activity at Soufrière Hills continued at a high level. Lava-dome growth remained focussed on the N side of the dome complex, with the development of a massive curved lobe of lava. During the early part of the week, the lobe repeatedly crumbled, producing rockfalls and small pyroclastic flows that reached the upper portion of Tuitt's Ghaut. Limited activity occurred on the NW part of the dome, although one small pyroclastic flow occurred in the notch between the central and north-western buttresses. Over the last 3 days of the report period, rockfall activity decreased substantially. This was due to the lobe becoming more coherent and not collapsing, not due to the activity stagnating. During the report week SO2 mass flux increased.

Source: Montserrat Volcano Observatory (MVO)


31 July-6 August 2002

Volcanic and seismic activity at Soufrière Hills during 26 July-2 August continued at an elevated level. The swarm of low-amplitude long-period earthquakes that began on 19 July continued, but decreased during the last 3 days of the report period. A flight on 1 August revealed that the new extrusion lobe on the N side of the summit had a broad whaleback form. Growth of the lobe was directed toward the N, giving rise to rockfalls and small pyroclastic flows in the upper parts of Tuitt's Ghaut and White's Ghaut. Torrential rainfall produced mudflows in the Belham Valley in the early hours of 28 August. SO2flux remained low.

Source: Montserrat Volcano Observatory (MVO)


24 July-30 July 2002

Volcanic and seismic activity at Soufrière Hills during 19-26 July increased significantly in comparison to the previous week. A swarm of low-amplitude long-period earthquakes began on 19 July and increased in strength over the following 4 days. Observations of the lava dome on 21 July indicated that significant growth had recommenced, with the extrusion of a new lobe on the NE side of the summit region. Growth of the new lobe gave rise to rockfalls and small pyroclastic flows off the dome's NE flank. A notable event occurred on the morning of 23 July, when a minor collapse produced small but continuous pyroclastic flows for about an hour. These mainly flowed into the upper parts of Tuitt's Ghaut and down White's Ghaut for about half the distance to the coast. A few also flowed into the upper part of the Tar River Valley. A similar event, lasting for about 20 minutes, occurred in the early hours of the morning of 26 July. Sulphur dioxide flux was low at the beginning of the report period, but increased from 22 July onwards.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


17 July-23 July 2002

Activity at Soufrière Hills increased slightly during 12-19 July, but remained at relatively low levels. Observations of the lava dome on 15 July suggested that dome growth had continued at a very slow rate on the SE side of the dome. The level of rockfall activity from this active lobe increased slightly on 15 July, with a small pyroclastic flow traveling down the Tar River Valley at 0800. SO2 flux remained low.

Source: Montserrat Volcano Observatory (MVO)


10 July-16 July 2002

Volcanic and seismic activity at Soufrière Hills were at low levels during 5-12 July. No change in lava-dome morphology occurred. The level of rockfall activity increased slightly between the 6th and 8th, before decreasing to very low levels for the remainder of the week. SO2 fluxes remained low, but increased slightly over the last 3 days of the report period.

Source: Montserrat Volcano Observatory (MVO)


3 July-9 July 2002

During 28 June-5 July, volcanic and seismic activity were at very low levels at Soufrière Hills in comparison to the previous week. No change in lava dome morphology was observed during the report period. Heavy rain on the evening of 2 July generated substantial mudflows in Plymouth. The level of rockfall activity on the dome increased slightly on the morning of 3 July and a small, low ash cloud drifted over Plymouth around 1000. SO2 flux remained consistently low.

Source: Montserrat Volcano Observatory (MVO)


26 June-2 July 2002

Volcanic and seismic activity were at low levels during 21-28 June at Soufrière Hills. Growth of the extruded lobe on the SE side of the lava dome appeared to have stagnated. The number of rockfalls decreased abruptly on the afternoon of 22 June, remained at low levels for the rest of the week, and declined to very low levels during the last 3 days of the report period. SO2 emission rates also decreased to very low levels by the end of the report period.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


19 June-25 June 2002

Volcanic activity at Soufrière Hills during 14-21 June was slightly higher than it had been the previous week. Rockfall activity increased abruptly on the night of 14 June and remained at moderately high levels until the 18th, when it declined. The active lobe on the SE side of the lava dome continued to grow and was topped by a small, low-angle spine extruded towards the SE. Rockfalls and small pyroclastic flows traveled towards the E, and several small pyroclastic flows traveled down the volcano's NE flank.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


12 June-18 June 2002

Volcanic and seismic activity remained at low levels at Soufrière Hills during 7-14 June. The massive extrusive lobe on the SE side of the lava dome continued to grow steadily throughout the week, although there was a low level of rockfall and seismic activity. Minor rockfall activity occurred on the E flank of the dome, increasing slightly during the latter half of the week.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


5 June-11 June 2002

The level of volcanism at Soufrière Hills was low during 31 May-7 June. During 31 May-4 June, the lava dome was seen clearly for the first time in several months. Since early April a large lobe had been extruded on the SE side of the dome's summit. This lobe is 150 m wide and rises to 1,023 m a.s.l. Its upper surface is spiny and slab-like. A small lobe-like protrusion also developed on the W side of the summit. Minor rockfalls traveled down the E flank of the dome and the W flank of the summit.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


29 May-4 June 2002

During 24-31 May, the level of volcanism at Soufrière Hills decreased in comparison to the previous week. The summit region of the active lava dome was broad and blocky in appearance. Lava-dome growth appeared to have become concentrated on the SE, leading to rockfalls and small pyroclastic flows down the flank. There was little activity on the NE flank of the dome.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


22 May-28 May 2002

During 17-24 May, the level of volcanism at Soufrière Hills remained similar to that in the previous week. Cloudy conditions obscured visual observations, but lava-dome growth appeared to be concentrated on the volcano's E flank. Numerous rockfalls and small pyroclastic flows travelled to the upper portions of the Tar River Valley. The number of rockfalls increased slightly on the 21st, but declined again on the 23rd.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


15 May-21 May 2002

During 10-17 May, volcanic activity was generally higher than it had been the previous week. Lava-dome growth continued to be concentrated on the E flank. Rockfall, pyroclastic-flow, and long-period earthquake activity was relatively high during the first half of the report period, but declined slightly during 15-17 May.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


8 May-14 May 2002

During 3-10 May, the level of volcanism at Soufrière Hills was generally lower at the beginning of the report period than it had been the previous week, but it increased during the 8th to 10th. Growth of the lava dome to the E continued to produce rockfalls and small pyroclastic flows down the E flank. Beginning on 8 May, activity increased and rockfalls and pyroclastic flows were concentrated on the dome's NE flank. Incandescence was visible several nights during the report period.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


1 May-7 May 2002

Volcanism at Soufrière Hills during 26 April-3 May remained at high levels. The lava dome continued to grow on the E side of the dome complex. Numerous rockfalls and small pyroclastic flows occurred at the E face of the dome as a result of material spalling off of the active extrusion lobe. Pyroclastic-flow activity was confined mainly to the upper part of the Tar River Valley, although several flows reached the pyroclastic fan at the mouth of the valley, where it disgorged into the sea. SO2 emission rates decreased slightly during the report week.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


24 April-30 April 2002

Volcanic activity at Soufrière Hills was at high levels during 19-26 April. The direction of lava-dome growth switched during the earlier part of the week, becoming focussed on the southeastern part of the dome complex. Rockfalls travelled down the SE flank of the dome almost continuously. The lobe on the SE portion of the dome reached 1,041 m a.s.l. and the NE lobe, which had been highly active the previous two weeks, stagnated at a height of 1,020 m a.s.l. Fluctuations in SO2 emission rates appeared to reflect variations in the intensity of rockfall activity.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


17 April-23 April 2002

During 12-19 April, the level of volcanism at Soufrière Hills slightly decreased in comparison to the previous week. Lava-dome growth was concentrated on the SE area of the dome complex, although small rockfalls occurred in other areas. The lava dome evolved from a large striated lobe at the beginning of the week, to a series of small spines by week's end. Small, low-level ash clouds were occasionally visible on satellite imagery.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


10 April-16 April 2002

During 5-12 April, volcanism slightly decreased at Soufrière Hills in comparison to the previous week. Lava-dome growth over the entire summit region produced rockfalls that travelled predominately to the SE, E, and NE. Several pyroclastic flows travelled E for ~2 km down the Tar River Valley, reaching the sea. At the beginning of the report week, ash from ongoing rockfalls and venting of the dome fell to the NW and N of Montserrat.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


3 April-9 April 2002

During 29 March-5 April, volcanism slightly decreased at Soufrière Hills in comparison to the previous week. Lava-dome growth over the entire summit region produced rockfalls that travelled predominately to the SE, E, and NE. Several pyroclastic flows travelled E ~2 km down the Tar River Valley, reaching the sea. At the beginning of the report week, ash from ongoing rockfalls and venting of the dome fell to the NW and N of Montserrat.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


27 March-2 April 2002

During 23-29 March, the level of volcanism remained high at Soufrière Hills. Lava-dome growth continued to be focused to the E of the summit region, producing numerous rockfalls and small pyroclastic flows into the upper portions of the Tar River Valley. Minor amounts of rockfall debris from the NE flank of the dome spilled into the head of Tuit's Ghaut. During the first half of the report period, ash from venting, rockfalls, and pyroclastic flows drifted W over Plymouth and the Richmond Hill area. Later in the week, ash drifted to the NW and N and was deposited in populated areas. SO2 emission rates remained high (1,110-1,200 metric tons per day).

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


20 March-26 March 2002

The level of volcanic activity at Soufrière Hills remained high during 15-22 March. Lava-dome growth continued to be focused on the E side of the summit region. Throughout the report period large (50-70 m high), fast-growing, spines developed on the dome's summit. These spines periodically collapsed, producing pyroclastic flows down the volcano's E flank that sometimes reached the Tar River fan. Small ash clouds produced from these events reached ~1 km above the volcano and drifted westward over Plymouth and Richmond Hill. Ash predominately fell into the sea. SO2 emission rates remained high. Theodolite measurements of the dome taken on 20 March yielded a dome height of 1,039 m.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


13 March-19 March 2002

During 8-15 March, the level of volcanic activity at Soufrière Hills was higher than during the previous week. Activity began to increase on the 8th, remaining at elevated levels for the remainder of the report period. Lava-dome growth continued to be concentrated towards the E, sending rockfalls and small pyroclastic flows to the upper portions of the Tar River Valley. The summit of the dome had a generally spiny appearance and minor episodes of ash venting occurred from it. Incandescence was visible at the summit during the night. SO2 emission rates were higher than average during the week (430 to 860 metric tons per day).

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


6 March-12 March 2002

During 1-8 March, volcanism decreased at Soufrière Hills in comparison to the previous week. Lava-dome growth continued to be concentrated towards the E, sending rockfalls and small pyroclastic flows to the upper portions of the Tar River Valley. Incandescence was visible on the upper parts of the dome during the night. Minor episodes of ash venting occurred from the summit of the dome. SO2 emission rates decreased dramatically during the first half of the report period.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


27 February-5 March 2002

The level of volcanism at Soufrière Hills during 22 February-1 March was higher than it had been in previous weeks. The continued growth of the lava dome towards the E led to almost continuous rockfalls and small pyroclastic flows that travelled to the upper portion of the Tar River Valley. During the week a large, steeply inclined spine was extruded on the summit of the dome. By 26 February the spine was 90 m tall, making the volcano's summit 1,080 m a.s.l. This is the highest the summit has been during the entire eruption to date. Minor episodes of ash venting occurred from the summit throughout the report period.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


20 February-26 February 2002

During 15-22 February, volcanism was generally high at Soufrière Hills. Lava-dome growth continued to be focused on the E sector. Activity increased during the second half of the report period; near-continuous rockfalls and minor pyroclastic flows travelled down the volcano's E flank. Minor rockfalls were also observed on the N flank of the active lava dome. Minor episodes of ash venting occurred from the summit of the dome, and on a number of evenings large parts of the summit were incandescent. SO2emission rates decreased during the report period; on 16 February 600-780 metric tons were measured, while on 19 February 90-130 metric tons were measured.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


13 February-19 February 2002

During 8-15 February volcanism at Soufrière Hills decreased slightly in comparison to the previous week. Lava-dome growth continued to be focussed towards the E and NE, producing numerous rockfalls and small pyroclastic flows in the upper portions of the Tar River Valley. Minor rockfalls of old inactive dome material travelled W to the upper portion of the Gages region. Minor episodes of ash venting occurred throughout the report period and SO2 emissions were slightly lower than the previous week.

Source: Montserrat Volcano Observatory (MVO)


6 February-12 February 2002

During 1-8 February volcanism slightly increased at Soufrière Hills in comparison to the previous week. Lava-dome growth continued to be focused on the E and NE sides of the dome. The summit of the dome was blocky and massive, rather than covered with spines like it was during the previous week. New pyroclastic-flow deposits were seen in Tar River to the E of the volcano and in White River to the SW.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


30 January-5 February 2002

During 25 January-1 February, the level of activity at Soufrière Hills was similar to the previous week. Lava-dome growth continued on the E side of the dome, producing numerous rockfalls and small pyroclastic flows to the upper portion of the Tar River Valley. These events were of similar size and energy to those of the previous week. Minor episodes of ash venting occurred throughout the report period. Ash clouds rose to a maximum height of ~2.5 km a.s.l.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


23 January-29 January 2002

During 18-25 January, volcanic activity remained high at Soufrière Hills. Continued growth on the E side of the lava dome produced numerous rockfalls and small pyroclastic flows down the volcano's E flank. On the 21st the dome was crowned by a large 40- to 50-m tall spine inclined steeply upwards towards the E. While the number of rockfalls gradually decreased over the previous 3 weeks, their size and duration significantly increased during the report period, exceeding total energy rates during the past few months.

Source: Montserrat Volcano Observatory (MVO)


16 January-22 January 2002

During 11-18 January volcanic activity was slightly lower at Soufrière Hills compared to the previous week. Growth appeared to be concentrated on the lava dome's E flank, where intense rockfall activity and small pyroclastic flows continued. On 12 January a long-period earthquake was accompanied by an ash plume that rose to ~2.5 km above the dome. This event was followed by a series of pyroclastic flows that traveled down the Tar River Valley to the sea. A large steam plume was generated when the pyroclastic flows entered the sea. The steam plume and a dense ash cloud drifted W over the Plymouth, Richmond Hill, and Fox's Bay area. Minor mudflows occurred in the Belham Valley on the morning of 18 January.

Source: Montserrat Volcano Observatory (MVO)


9 January-15 January 2002

During 4-11 January volcanic activity remained high at Soufrière Hills. Observations on 10 January revealed that the summit region had increased in volume considerably over the past several weeks and that the lava dome was broad with several spines sticking out from it. The highest spine reached 1,015 m a.s.l. on the 12th. The western side of the zone appeared to be inactive. A large extrusion lobe was active on the upper E flank of the dome, just below the summit. The E flank of the dome was very active, producing numerous rockfalls and pyroclastic flows. On 5 January a series of pyroclastic flows traveled down the Tar River Valley to the sea. This event was accompanied by vigorous venting of ash from the summit, producing a pulsating ash-laden plume that drifted to the W. Seismicity remained at a similar level in comparison to the previous week. SO2 and HCl emissions were high; 898 and 1,122 metric tons of SO2 were measured on 1 and 10 January, respectively. Low-level ash emissions occurred throughout the week.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


2 January-8 January 2002

During 28 December-4 January volcanic activity at Soufrière Hills remained high, with vigorous rockfalls travelling down the volcano's E flank. The most notable event during the week was the collapse of several million cubic meters of volcanic material down the volcano's NE flank on 28 December. The collapse, during about 1330-1500, continuously generated pyroclastic flows down the Tar River Valley to the sea. A dense W-drifting ash plume was generated that deposited up to a centimeter of ash in the vicinity of the town of Plymouth. The average flux of SO2 in the volcanic plume was ~460 metric tons on 3 January, in comparison to 851 metric tons measured on 27 December. A 30-minute-long sustained event began on 5 January around 1640 and produced an ash cloud to a height of ~2.4 km a.s.l.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


26 December-1 January 2002

During 21-28 December volcanic activity increased at Soufrière Hills, with a large number of rockfalls, an increase in SO2 flux, and periods of continuous ash emission. Most lava-dome growth was concentrated on the E side of the dome, where spectacular incandescent rockfalls were seen on the nights of 26 and 27 December. Rockfall seismicity increased throughout the week. There was a large increase in SO2 flux; an average emission rate of 851 metric tons was measured on 27 December in comparison to 181 metric tons on 19 December. The increase in SO2 flux coincided with an increase in rockfalls. According to the Washington VAAC, continuous ash-and-steam venting beginning on 27 December at 0315 produced an ash plume that remained below ~3 km a.s.l. A large area of dense ash below 3 km a.s.l. was observed on satellite imagery from an emission that began on 28 December at 1330. On 1 January a high number of rockfalls generated low-level ash clouds (up to 1.5 km).

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


19 December-25 December 2001

During 14-21 December, volcanic activity at Soufrière Hills remained high. Observations of the lava dome on 16 December revealed that it had increased in volume since it was last seen in late November. The top of the dome was broadly rounded and had a blocky appearance. Most of the growth appeared to occur on the W side of the dome, but rockfalls and small pyroclastic flows also occurred on the E and S flanks. Periods of weak, but sustained ash-venting occurred on most days and seismicity was dominated by rockfall signals. Intense rainfall on the morning of 21 December produced large mudflows NW of the volcano in Belham Valley.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


12 December-18 December 2001

High levels of volcanic and seismic activity continued at Soufrière Hills during 7-14 December. Seismicity was dominated by signals attributed to rockfalls, which gradually increased throughout the week. Continuous, weak tremor recorded on 13 December was associated with ash venting, and produced columns that rose to at least 4 km.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


5 December-11 December 2001

Volcanic activity at Soufriere Hills remained at a high level, similar to the previous week. Elevated activity on 2 December produced pyroclastic flows in the Tar River Valley that reached the sea. The flows originated in several places along the E face of the new lava dome. Two small pyroclastic flows also occurred in the upper reaches of White River, originating from the old dome material closest to Chances Peak. Short periods of pyroclastic-flow activity occurred in both valleys on 4 and 6 December. On 8 December a low-level plume of ash (~1.8 km a.s.l.) was visible extending ~140 km to the W of the volcano.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


28 November-4 December 2001

Volcanic activity at Soufrière Hills remained at a high level, similar to the previous week. Lava dome growth on the western side of the dome complex produced rockfalls to the W that were confined by the collapse scar formed on 29 July 2001. The dome complex consists of the stagnant E lobe (870 m a.s.l.), an inactive central lobe (930 m a.s.l.), and the active W lobe (960 m a.s.l. on 27 November). The hybrid and long-period earthquake swarm, which began on the 14th of November, continued without intensifying. Low-level ash emissions occurred on 3 December.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


21 November-27 November 2001

The level of volcanic activity at Soufrière Hills increased during 16-23 November in comparison to the previous week. Morphological changes were observed at the volcano's summit; lava-dome growth shifted from the E to the W and the summit area was crowned by spines with an average elevation of 940 m a.s.l. Rockfall activity was relatively low, but intensified towards the end of the report week. Rockfalls were mainly concentrated on the W side of the active area, rather than the E as in previous weeks. Incandescent material was visible at night on the E and W sides of dome. A hybrid and long-period earthquake swarm began on 14 November, reaching a peak on 21 November before slightly declining.

Source: Montserrat Volcano Observatory (MVO)


14 November-20 November 2001

Volcanic activity at Soufrière Hills during 9-16 November was generally diminished compared to the previous week. The lava dome continued to grow mainly towards the E and its highest point was measured on 9 November to reach 876 m a.s.l. Small pyroclastic flows and rockfalls were generated by material avalanching off the flanks of the dome. The largest of these events was a pyroclastic flow on the night of 14 November, which travelled E and reached the lower parts of the Tar River Valley. The seismicity cycles, which had been a dominant feature since early August, appeared to have stopped. Rockfall seismicity was most intense on 9 and 10 November, but then declined significantly and remained low after 12 November. The Washington VAAC reported that ash was visible in satellite imagery on 17 November at 0845 below 6.1 km a.s.l. and on 18 November at 0845 below 3 km a.s.l., extending ~42 km NE towards Antigua. The satellite imagery showed that a thin portion of the ash cloud may have reached Antigua.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


7 November-13 November 2001

Activity at Soufrière Hills increased slightly during 2-7 November, and intensified on the 8th and 9th. The lava dome continued to grow mainly towards the E and at night parts of it were incandescent. Small pyroclastic flows and numerous rockfalls were generated by material avalanching off the flanks of the dome; they travelled mainly down the volcano's eastern flank, and to a lesser extent down the NE flank. On 8 November observations from a helicopter revealed that a shallow, circular depression was located over the summit area of the dome, with ash vigorously venting from it. On several days a low-level plume, with small amounts of ash, drifted to the W or N. Cycles of weak and sporadic seismicity occurred, with periods of more intense seismicity characterized by increased rockfall activity and hybrid earthquakes. Mudflows occurred in the Belham Valley on the morning of 9 November during a period of heavy rainfall.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


31 October-6 November 2001

Beginning on 26 October, seismicity at Soufrière Hills was at low levels until it increased on 1 November. Clear weather conditions allowed observations of the lava dome on 31 October and 1 November. The active lava dome had grown substantially and appeared to switch growth direction from the NE to the E, where a massive, near-vertical headwall had developed. Several small pyroclastic flows were generated by material avalanching off the eastern flank of the dome. Cycles of mostly hybrid earthquakes, with a coincident increase in rockfalls, were weak until they strengthened on 1 November. Mudflows occurred in the Belham Valley during several days with periods of torrential rainfall.

Source: Montserrat Volcano Observatory (MVO)


24 October-30 October 2001

During 19-26 October there was a general reduction in volcanic activity at Soufrière Hills in comparison with the previous week, while seismicity remained at a similar level. The active lava dome continued to grow at a moderate rate, producing rockfalls and small pyroclastic flows in the upper reaches of the Tar River Valley. Cycles of mostly hybrid earthquakes, with a coincident increase in rockfalls, recommenced after weakening for about a week. Mudflows occurred in the Belham Valley during several days with periods of torrential rainfall.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


17 October-23 October 2001

During 12-19 October activity at Soufrière Hills remained at an elevated level, although there was a reduction in seismicity compared with the previous few weeks. The cyclical nature of the seismic activity, which had been a dominant feature over recent months, also weakened. The active lava dome continued to grow at a moderate rate, producing pyroclastic flows on most days into the upper reaches of the Tar River Valley. Two significant collapse events occurred during the reporting period involving residual material from the dome that formed prior to the 29 July dome. On 14 October, after a day of torrential rainfall, several million cubic meters of unconsolidated talus was destabalized on the SE flank of the pre-July 29 dome. This material produced sustained pyroclastic flows E down the Tar River Valley, reaching the sea. Seismic data suggested that the event began at about 1715, peaked at 2245, and ended at about 2300. Ash from the event drifted to the NW and fell in residential areas between Iles Bay and St Peter's. On the morning of 16 October a collapse occurred on the S flank of the dome complex, producing numerous pyroclastic flows W down the White River approximately two-thirds of the distance to the sea. Mudflows occurred in the Belham Valley during several days with periods of torrential rainfall.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


10 October-16 October 2001

During 5-12 October volcanic activity at Soufrière Hills remained at elevated levels, although there was a marked reduction in the number of hybrid earthquakes compared with the previous few weeks. Numerous pyroclastic flows were produced by material avalanching off of the lava dome, which continued to grow in the summit crater at a moderate rate. The flows were relatively small, but energetic, and were confined to the upper and middle reaches of the Tar River Valley to the E of the volcano. Associated ash clouds drifted to the W and NW, occasionally depositing small amounts of ash on inhabited areas on the N part of the island. According to the Washington VAAC, ash clouds did not rise over ~2 km a.s.l. Avalanching talus on the S flank of the previous lava dome produced a pyroclastic flow that traveled SW down the White River approximately two-thirds of the distance to the sea. Mudflows occurred in the Belham Valley during several days with periods of torrential rainfall. The daytime entry zone was reopened on 11 October, following its temporary closure the previous week.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


3 October-9 October 2001

During 28 September to 5 October volcanic activity at Soufrière Hills increased in comparison to the previous week. Numerous pyroclastic flows were produced by material avalanching off the lava dome, which continued to grow in the summit crater at a moderate rate. Most of the pyroclastic flows during the report period were small and confined to the upper reaches of the Tar River Valley E of the volcano, but larger flows occurred on 4 and 5 October. On 4 October a small-scale lava-dome collapse (consisting of 10-15% of the dome's volume) on the N side of the dome produced sustained pyroclastic-flow activity between 0745 and 0915, with at least three flows reaching the sea. Similar activity occurred on 5 October at 0845 until at least midday. Dense ash clouds generated during both periods of elevated pyroclastic-flow activity were visible on satellite imagery rising to ~1.8 km a.s.l. and drifting to the W. Seismicity continued to be dominated by bands of hybrid earthquakes and rockfalls.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


26 September-2 October 2001

Volcanic activity at Soufrière Hills during 21-28 September was similar to the previous week, except for a slight reduction in the number of hybrid earthquakes. Seismicity continued to be dominated by bands of hybrid earthquake swarms and increased rockfall activity with periodicities of approximately 11 to 13 hours. The active lava dome continued to grow at a moderate rate, producing rockfalls and small but energetic pyroclastic flows that traveled E to the upper reaches of the Tar River Valley. Periods of vigorous ash venting were associated with the hybrid-earthquake swarms. Steam-and-ash clouds were visible on satellite imagery rising to ~500 m above the volcano.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


19 September-25 September 2001

There was a moderate increase in volcanic activity at Soufrière Hills in comparison to the previous week. A marked increase in hybrid earthquake events was recorded and banded tremor events were slightly more intense. In addition, the number and strength of hybrid events associated with the banded tremor increased. The active lava dome continued to grow at a moderate rate, producing rockfalls and small pyroclastic flows that traveled E to the upper reaches of the Tar River Valley. The dome's volume was estimated to be 12 million cubic meters, therefore, the average growth rate has been ~2.6 cubic meters per second since the partial dome collapse on 29 July. Episodes of vigorous ash venting and increased rockfall activity occurred during periods of tremor. Low-level ash plumes from this activity were visible in satellite imagery.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


12 September-18 September 2001

Activity at Soufrière Hills remained at levels similar to the previous week. Bands of tremor, associated with rockfalls and ash venting, occurred at irregular intervals. On 12 September continuous low-amplitude tremor began and persisted until at least 14 September. The tremor accompanied rockfalls. The active lava dome continued to produce rockfalls and small pyroclastic flows that descended into the upper reaches of the Tar River Valley. Ash clouds produced from rockfalls rose slightly above the summit and were visible in satellite imagery.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


5 September-11 September 2001

Activity at Soufrière Hills remained at similar levels as during the previous week. Bands of tremor, associated with rockfalls and ash venting, occurred at irregular intervals. The active lava dome appeared to be growing rapidly and was well-formed, with steep sides and a rugged summit area. Rockfalls and small pyroclastic flows that originated from the new dome were observed in the upper reaches of the Tar River Valley. On the night of 3 September incandescence was visible at the dome. According to the Washington VAAC, rockfalls generated ash clouds that did not rise above ~1.5 km a.s.l.

Source: Montserrat Volcano Observatory (MVO)


29 August-4 September 2001

Activity at Soufrière Hills remained at similar levels as during the previous weeks. Following the partial dome collapse on 29 July bands of tremor, which indicate rapid magma ascent, occurred at 13-27 hour intervals. During these banded-tremor events rockfall activity and ash venting increased, sending ash up to ~2 km above the volcano, drifting to the W. A weak swarm of volcano-tectonic earthquakes (less than M 1) began on 29 August. Observations revealed that the new lava dome had a well-formed dome-like morphology and appeared to have rapidly grown in the scar produced by the 29 July collapse. Rockfalls and small pyroclastic flows that originated from the new dome were observed in the upper reaches of the Tar River Valley. The daytime entry zone was re-opened on 29 August.

Source: Montserrat Volcano Observatory (MVO)


22 August-28 August 2001

Volcanic activity at Soufrière Hills remained at a similar level as the previous week, except for an increase in hybrid seismic events. Rockfalls and pyroclastic flows observed in the upper reaches of the Tar River Valley appeared to originate from the new dome, which was obscured by meteorological clouds. After 22 August, banded tremor that had increased the previous week declined to low levels. The Washington VAAC reported that an ash emission occurred on 26 August at 1215, rose to ~2 km, and drifted to the SW.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


15 August-21 August 2001

Volcanic activity remained low during 10-17 August. Weak banded tremor began on 14 August and continued throughout the week. The new lava dome continued to grow within the scar produced from the 29 July partial dome collapse. Deposits in the upper reaches of the Tar River Valley indicated that the new dome had produced several small pyroclastic flows.

Source: Montserrat Volcano Observatory (MVO)


8 August-14 August 2001

During the week volcanic activity was low at Soufrière Hills. Small-scale rockfalls and minor pyroclastic flows occurred mainly off of the sides of the scar left after the partial dome collapse on 29 July. Like the previous week, a new dome was seen growing within the scar.

Source: Montserrat Volcano Observatory (MVO)


1 August-7 August 2001

Volcanic activity rapidly declined after the lava dome at Soufrière Hills partially collapsed on 29 July. Observation flights after the collapse revealed that the general summit region had been lowered by about 150 m. There was also a complex amphitheater-shaped scar several hundred meters deep incised into the core of the dome at the head of the Tar River Valley. A new dome was growing within the scar. The Washington VAAC reported that a minor eruption occurred on 4 August at 0300. The eruption produced ash that traveled in two different directions; the first ash cloud rose to ~4.6 km a.s.l. and drifted NW; the second cloud rose to ~9.7 km a.s.l. and drifted NE.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC), Associated Press, Reuters


25 July-31 July 2001

On 29 July ash from Soufrière Hills drifted W, leaving deposits as far away as San Juan, Puerto Rico, 450 km to the WNW. The Washington VAAC issued an advisory on 27 July stating that a steady stream of ash was emitted from the volcano through the evening, rising to 800 m. There was also a persistent, strong hot spot over the volcano's summit visible in satellite imagery. According to MVO, the amount of ash emitted from the volcano increased during 27 July through 29 July, and seismic activity rose on 29 July. Beginning at 1500 on 29 July heavy rainfall mixed with ash deposits and generated lahars that flowed NW down the Belham River. The lava dome that had been growing in the summit region of the volcano during recent years partially collapsed, generating pyroclastic flows that traveled down the E flank of the volcano and entered the sea. Shortly after 1700 observers reported seeing pyroclastic flows and a continuous dense plume of ash that drifted to the W. Dense meteorological clouds, associated with a tropical wave, crossed the island and prohibited ash cloud detection in satellite imagery or ground confirmation of the height of the ash cloud. MVO reported that the large amount of ash that was being vented from the volcano rose to below 6 km. By midnight seismic and pyroclastic flow activity returned to low levels. The next day AVHRR imagery showed possible ash in an area W of Montserrat and SE of Puerto Rico. The position of the cloud correlated with ground observations of ash and haze from Christiansted, St. Croix.

There were reports of substantial ashfall and sporadic falling of "stones" in the Montserrat residential areas of Salem and Olveston in the N part of the island. Ash also fell in the US and British Virgin Islands, Roosevelt Roads (Puerto Rico), Christiansted (St. Croix), and as far as 450 km away from the volcano in San Juan (Puerto Rico). The ashfall in San Juan and the surrounding area led to the closing of the San Juan International Airport on 30 July. The airport reopened the next day.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC), Associated Press, Reuters


18 July-24 July 2001

The number of rockfalls increased (719) during 13-20 July in comparison to the previous week (297), although most of them were very small. Near-continuous rockfalls occurred on the S side of the lava dome, where dome growth was concentrated. Numerous pyroclastic flows originated from the S flank of the dome and moved eastward down the Tar River Valley. Several pyroclastic flows also originated from the W side of the dome and traveled short distances into the upper part of the Gages area. On 23 July at 1145 a pilot reported spotting an ash cloud approximately 800 m above the volcano. Satellite imagery at that time detected a faint ash-and-steam plume and an occasional hot spot.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


11 July-17 July 2001

During 6 to 13 July volcanic activity at Soufrière Hills remained similar to the previous week. Lava dome growth appeared to still be concentrated on the S side of the dome where near-continuous rockfalls occurred. According to the Washington VAAC, the rockfalls produced ash plumes that did not rise above 3 km a.s.l. and drifted to the W or WNW. An occasional hot spot was visible on satellite imagery.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


4 July-10 July 2001

During 29 June to 6 July volcanic activity at Soufrière Hills remained similar to the previous week. Lava dome growth appeared to still be concentrated on the S side of the dome above the White River. On 30 June a large number of rockfalls traveled down the N side of the talus apron in the Tar River. On 4 July two small pyroclastic flows traveled down the volcano's W flank in the Amersham area. The Washington VAAC reported that on 4 July an ash cloud rose ~3 km a.s.l. and drifted to the WNW. Also, on 10 July numerous rockfalls produced W-drifting ash plumes that did not exceed ~3 km a.s.l. in height.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


20 June-26 June 2001

During 15-22 June volcanic activity remained at about the same level as the previous week. The number of rockfalls increased in comparison to the previous week, while other types of seismic events generally decreased. Towards the end of the week the number of rockfalls also decreased slightly. Growth was still concentrated in the S sector of the lava dome above the town of Galway's. Small, near-continuous rockfalls occurred in the upper part of White River. Sulfur dioxide flux decreased slightly.

Source: Montserrat Volcano Observatory (MVO)


13 June-19 June 2001

From 12 June to at least 15 June volcanic activity increased at Soufrière Hills in comparison to the previous week. There was a larger number of rockfalls, and hybrid and long-period earthquakes. Sulfur dioxide flux markedly increased (770 metric tons on 11 June and 1410 metric tons on 14 June). New growth was substantial in the southern sector of the lava dome and there was a large accumulation of new dome material SW of the dome in the upper reaches of the White River. The daytime entry zone was open for limited periods during the week. The Washington VAAC reported that at 0510 on 14 June a small ash cloud rose 3-4.5 km a.s.l. and drifted to the W and that low-level ash was emitted throughout the week. In addition, moderate rockfall activity produced ash to ~2 km a.s.l. and a hot spot was occasionally visible on satellite imagery.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


6 June-12 June 2001

Earthquake activity decreased through the week of 1-8 June. Good views of the lava dome were hampered by clouds, but observations of rockfall activity confirmed that the main growth area was still concentrated in the southern sector of the dome. Sulfur dioxide fluxes were higher on 4 June than 1 June, with an average daily flux of 320 tons per day, compared to only 130 tons per day on 1 June. The daytime entry zone remained closed.

Source: Montserrat Volcano Observatory (MVO)


30 May-5 June 2001

MVO reported that during 25 May-1 June volcanic activity remained at high levels. There was a significant increase in long-period earthquakes, although most were small. MVO personnel observed an area of new growth in the S sector of the lava dome. Sulfur dioxide flux varied, but was generally lower than the previous week. The daytime entry zone remained closed.

Source: Montserrat Volcano Observatory (MVO)


23 May-29 May 2001

MVO reported that during 18-25 May volcanic activity increased in comparison to the previous week. The main increase in activity occurred during 19 to 21 May when many large long-period and hybrid earthquakes were recorded. Low-level convective ash clouds generated during this increase in activity rose less than 2 km a.s.l. Observations confirmed that the main growth area was still concentrated in the S sector of the lava dome. A large volume of new talus had built out above the White River, to the S of the volcano, and on 24 May near-continuous rockfalls and small pyroclastic flows were observed. Sulfur dioxide flux increased, with an average of 700 metric tons per day measured on 21 May, considerably higher than the average flux during previous weeks of 100 to 200 tons per day. Due to the increase in activity the daytime entry zone was closed beginning on 21 May.

Source: Montserrat Volcano Observatory (MVO)


16 May-22 May 2001

MVO reported that during 11-18 May volcanic activity increased, with about twice the number of rockfalls than the previous week. Most of the rockfalls were small and were observed to the SW of the summit, N of the town of Galway's. Growth of the lava dome was concentrated in the S sector of the volcano above White River. A new lobe of lava was observed in the area, although the rate of growth appeared to be low. Sulfur dioxide flux remained low. Most of Montserrat received very light ashfall throughout the week as a result of changeable winds.

Source: Montserrat Volcano Observatory (MVO)


9 May-15 May 2001

MVO reported that during 4-11 May volcanic activity increased slightly, with more rockfalls and seismic activity recorded than the previous week and a small pyroclastic flow on 9 May. The pyroclastic flow traveled ~2.5 km S of the dome down the White River. There still appeared to be a very small amount of growth in the S side of the lava dome, and observation flights confirmed that most rockfall activity occurred in the dome's S sector. Sulfur dioxide flux remained low.

Source: Montserrat Volcano Observatory (MVO)


2 May-8 May 2001

MVO reported that during 27 April- 4 May volcanic activity at Soufrière Hills remained low, although there was a slight increase during 28 and 29 April. An increase in rockfall activity occurred from 28 April to 1 May; there were 16 rockfalls on 29 April, 34 on 30 April, and 15 on 1 May. For the previous six weeks there had usually been less than 10 rockfalls per day. The increase in activity may have been due to heavy rain on 29 and 30 April. A very small amount of growth occurred on the S side of the lava dome, which was accompanied by occasional ash venting. Sulfur dioxide flux remained low. MVO warned that although activity is low, dangerous conditions can develop quickly and in the event of heavy rain the Belham Valley to the NE of the volcano should be avoided due to the possibility of mudflows.

Source: Montserrat Volcano Observatory (MVO)


25 April-1 May 2001

MVO reported that during 20-27 April volcanic activity at Soufrière Hills remained low, with few rockfalls and little seismicity. A very small amount of growth occurred on the S side of the lava dome, which was accompanied by occasional ash venting. Sulfur dioxide flux also remained low.

Source: Montserrat Volcano Observatory (MVO)


18 April-24 April 2001

MVO reported that during 13-20 April volcanic activity at Soufrière Hills remained low, with few rockfalls and little seismicity. A swarm of hybrid earthquakes occurred primarily during 0419 to 0741 on 20 April. A very small amount of growth occurred on the S side of the lava dome, which was accompanied by occasional ash venting. Sulfur dioxide flux also remained low.

Source: Montserrat Volcano Observatory (MVO)


11 April-17 April 2001

MVO reported that during 6-13 April volcanic activity at Soufrière Hills remained low. Seismic and rockfall activity were low and there was a small amount of growth on the S side of the lava dome. Sulfur dioxide flux also remained low. MVO warned that although activity is low, dangerous conditions can develop quickly and in the event of heavy rain the Belham Valley to the NE of the volcano should be avoided due to the possibility of mudflows.

Source: Montserrat Volcano Observatory (MVO)


4 April-10 April 2001

The MVO reported that during 30 March- 6 April volcanic activity at Soufrière Hills remained low. Like last week, seismic and rockfall activity were low and there was a small amount of growth in the S of the lava dome. Sulpher dioxide fluxes also remained low. The MVO warned that though activity is low, dangerous conditions can develop quickly and in the event of heavy rain the Belham Valley to the NE of the volcano should be avoided due to the possibility of mudflows.

Source: Montserrat Volcano Observatory (MVO)


28 March-3 April 2001

The MVO reported that during 23-30 March volcanic activity at Soufriere Hills volcano was extremely low. Seismic and rockfall activity were low and there was a small amount of growth in the S of the lava dome. The MVO warned that though activity is low, dangerous conditions can develop quickly and in the event of heavy rain the Belham Valley to the NE of the volcano should be avoided due to the possibility of mudflows.

Source: Montserrat Volcano Observatory (MVO)


21 March-27 March 2001

The MVO reported that during 16-23 March activity at Soufrière Hills remained at low levels. Most of the 84 detected rockfalls were small events and occurred on the eastern and southern faces of the lava dome. There has been a small amount of growth in the south part of the dome. Sulfur dioxide fluxes have also been low this week. Traverse measurements under the plume gave fluxes ranging between 120 and 190 metric tons per day for the three days of measurements.

Source: Montserrat Volcano Observatory (MVO)


14 March-20 March 2001

The MVO reported that during 9-16 March activity decreased at Soufrière Hills volcano in comparison to the previous week, with the lava dome continuing to steadily grow. Seismic activity significantly decreased relative to the previous few weeks. Observations confirmed that most rockfall activity occurred to the S down the White River, with occasional rockfalls towards the E down Tar River Valley.

Source: Montserrat Volcano Observatory (MVO)


7 March-13 March 2001

The MVO reported that during 2-9 March activity decreased at Soufrière Hills volcano in comparison to the previous week, with the lava dome returning to a steady growth rate. Early in the report week the banded tremor recorded the previous week died away, as did the associated hybrid earthquakes. Rockfall activity increased during the middle of the week, returning to more usual levels. The volcano appeared to have resumed steady dome growth by the end of the week. Observations confirmed that the main area of lava-dome growth had switched to the S of the dome on 25 February, which led to a concentration of rockfall activity in the upper portions of the White River Valley. Light ashfall from activity during the week was blown over the N of the island, although by the end of the week the wind switched back to the more usual direction towards the W. The Washington VAAC reported that throughout the week low-level ash clouds (up to ~3 km a.s.l.), presumably produced by rockfalls, and periodic hot-spot activity were visible on GOES-8 imagery.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


28 February-6 March 2001

The MVO reported that during 23 February to 2 March activity at the Soufrière Hills volcano increased with a marked change in the character of the seismicity, a change in the direction of lava dome growth, and moderate levels of pyroclastic flow activity. An unusually large number of hybrid earthquakes (388) were recorded during the week. On 24 February dome growth was concentrated on the NE side of the lava dome, but the next day the area of growth changed to the S side of the dome. After the change in activity, a small collapse occurred towards the SW down the White River Valley and produced small pyroclastic flows that stopped just short of the sea and started fires in Shooters Hill. Throughout the rest of the week rockfalls and small pyroclastic flows traveled to the top of the White River Valley, with only occasional ones traveling in other directions. This activity was accompanied by banded tremor and weak hybrid earthquakes. The Washington VAAC reported that throughout the week low-level ash clouds (up to ~3 km a.s.l.), presumably produced by rockfalls, and periodic hot-spot activity were visible on GOES-8 imagery.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


21 February-27 February 2001

The MVO reported that during 16 to 23 February activity at the Soufrière Hills volcano was similar to the previous week, as lava dome growth continued. The level of seismic activity was also comparable to last week. A large stubby spine was visible in the S part of the summit area on 22 February. The top of the spine was measured as 1,068 m a.s.l. and the main summit area was about 1,030 m a.s.l. New pyroclastic-flow deposits were emplaced towards the E, down Tar River as far as the old coastline, and to the S in the White River Valley as far as 50 m short of the coast on the new pyroclastic delta. Many rockfalls descended the NE flank of the dome into the upper reaches of Tuitt's Ghaut. The Washington VAAC reported that throughout the week low-level ash clouds (up to ~3.4 km a.s.l.), presumably produced by rockfalls, and periodic hot-spot activity were visible on GOES-8 imagery.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


14 February-20 February 2001

The MVO reported that during 9 to 16 February activity at the Soufrière Hills volcano fluctuated markedly, as lava dome growth continued. The level of seismic activity varied considerably, with a pronounced peak in activity during 10 and 11 February, which was followed by a gradual decrease in rockfall activity. Observations revealed that the two large spines that were visible on the volcano's summit the previous week had collapsed, and a large lobe had formed on the eastern face of the dome above Tar River. New pyroclastic-flow deposits were observed down the Tar River extending to the old coastline. Small-volume deposits were observed down White River to the S and in Tuitt's Ghaut to the NE. The Washington VAAC reported that throughout the week low-level ash clouds (up to ~2.1 km a.s.l.), presumably produced by rockfalls, were visible on GOES-8 imagery.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


7 February-13 February 2001

The MVO reported that during 2 to 9 February activity at the Soufrière Hills volcano was slightly higher than during the previous week as lava dome growth continued. Seismic activity remained similar to the previous week, although it increased towards the end of the report week. Rockfall activity was low during the beginning of the week, but significantly increased beginning on 6 February; only 9 rockfalls were recorded on 5 February, while 70 were recorded on 6 February. Brief observations revealed that volcanic activity remained concentrated on the E side of the lava dome and that two large near-vertical spines stood on the dome's summit. By 8 February new pyroclastic-flow deposits were emplaced at the head of Tuitt's Ghaut ~300 m to the N of the dome. The Washington VAAC reported that throughout the week low-level (up to ~2.1 km a.s.l.) ash clouds, presumably produced by rockfalls, and periodic hot-spot activity were visible on GOES-8 imagery.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


31 January-6 February 2001

The MVO reported that activity at the Soufrière Hills Volcano was lower than during the previous week, although the lava dome continued to grow. The level of seismicity was also generally lower. During the morning of 29 January a very low-energy swarm of 20 volcano-tectonic earthquakes occurred to the NE of the volcano. During the week, brief observations revealed that volcanic activity remained concentrated on the SE side of the dome. On 1 February, a small pyroclastic flow was observed in the White River Valley. It traveled ~1 km to the SE and produced a small ash cloud that rose to a maximum height of ~1.5 km a.s.l.

Source: Montserrat Volcano Observatory (MVO)


24 January-30 January 2001

Activity at the Soufrière Hills volcano during 19-26 January was lower than the previous week, although the lava dome exhibited continued growth. Compared to last week, seismic activity was reduced and the number of rockfalls more than halved. Activity continued to be concentrated on the SE side of the lava dome, with a large slabby lobe extruded above the Tar River Valley, which is to the E of the volcano.

Source: Montserrat Volcano Observatory (MVO)


17 January-23 January 2001

Activity at the Soufrière Hills volcano during 12-19 January was similar to the previous week, with continued growth of the summit lava dome and high levels of mostly low-energy rockfalls. The overall level of seismic activity remained high. Activity was concentrated on the SE side of the lava dome, although some new pyroclastic-flow deposits were seen to the NE of the volcano. The Washington VAAC reported that low level ash, presumably produced from rockfalls, was occasionally visible on GOES-8 imagery. Less ash fell across the N portion of Montserrat than during the previous week.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


10 January-16 January 2001

Activity at Soufrière Hills during 5-12 January remained elevated with continued growth of the lava dome and rockfalls. The broadband seismic network recorded 1,076 rockfall signals during the reporting period. Growth continued in the summit area with a large amount of debris being shed down the E face of the dome, although the focus of activity seemed to be on the SE side of the dome later in the week. A small amount of rockfall activity occurred down the S side, entering the upper reaches of the White River Valley. The results from a recent dome survey revealed that about 64 million cubic meters of lava have been extruded since 20 March 2000, an extrusion rate for March-December 2000 of about 3 m3/s. On 10 January, a series of static COSPEC scans of the volcanic plume gave SO2-flux values of 400-700 metric tons per day. On 11 January, measurements from a helicopter averaged 640 metric tons per day.

GOES-8 visible infrared and multispectral imagery interpreted by the Washington VAAC showed a low-level plume on the late afternoon to early evening of 9 January that was 9 km wide and extended 41 km WNW. An occasional hot spot was also detected on the 10th.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


3 January-9 January 2001

Activity at the Soufrière Hills volcano during 29 December to 5 January was similar to the previous week, with continued growth of the summit lava dome and high levels of rockfall activity. The overall level of seismic activity remained high. In addition, at 0406 on 5 January a regional earthquake was felt on Montserrat. According to the volcano observatories on Martinique and Guadeloupe, the earthquake's epicenter was about 40 km E of the island of Marie Galante, and had a provisional magnitude of 4.6. Marie Galante lies ~200 km SE of Montserrat. Lava dome growth continued, producing rockfalls predominately to the E, and to a lesser extent, to the S and W areas of the new growth. The spine growing atop the lava dome reached a maximum height of 1,052 m a.s.l. by the end of the report week. The Washington VAAC reported that throughout the week low-level (up to ~3 km a.s.l.) ash clouds, presumably produced by rockfalls, and periodic hot-spot activity were visible on GOES-8 imagery. Winds blew small amounts of ash to inhabited areas in the N and W of the island.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


27 December-2 January 2001

Activity at the Soufrière Hills volcano remained at an elevated level during 22-29 December, with continued growth of the lava dome and high levels of rockfall activity. The overall level of seismic activity remained high. Rockfall signals were often immediately preceded by long-period events, indicative of explosive onsets. This was confirmed by visual observations of vigorous ash venting prior to and during rockfall activity. Lava dome growth continued at the summit, producing rockfalls predominately to the E, and to a lesser extent, to the S and W area of the new growth. The spine that was growing on top of the lava dome reached a maximum height of 1,071 m a.s.l. The Washington VAAC reported that throughout the week low-level (below 2.4 km a.s.l.) ash clouds that were produced by rockfalls, and periodic hot spot activity were visible on GOES-8 imagery. Wind conditions during the week resulted in a small amount of ash being deposited in inhabited areas in the N and W of the island.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


20 December-26 December 2000

The Washington VAAC reported that throughout the week low-level (up to ~2 km) ash clouds that were produced by rockfalls, and periodic hot spot activity were visible on GOES-8 imagery.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


13 December-19 December 2000

Activity at the Soufrière Hills volcano remained at an elevated level during 8-15 December, with continued growth of the lava dome. Seismic activity was comparable to last week and the main focus of volcanic activity remained on the E flank. Near-continuous rockfalls and ash venting occurred from the summit area, producing ash clouds that traveled to the W of the volcano. GOES-8 imagery showed that the clouds did not rise above 3 km and that hotspots were occasionally visible. SO2 values were significantly lower than values measured over the previous 2 months.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


6 December-12 December 2000

The MVO reported that during 1-8 December volcanism continued at an elevated level, with continued growth of the lava dome. Seismic activity was comparable to the previous week. The main focus of activity remained on the volcano's eastern flanks, although some small rockfalls were observed on the western side of the new growth. Rockfalls and small pyroclastic flows regularly traveled to the NE down the upper reaches of Tuitt's Ghaut. The dome was observed intensely glowing. Spines continuously grew and collapsed on the summit of the dome, with the highest spine reaching 1,060 m a.s.l. Strong hot spots, and low-level ash clouds (<2 km a.s.l.) associated with the numerous rockfalls and pyroclastic flows were visible on GOES-8 imagery.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


29 November-5 December 2000

The MVO reported that during 24 November-1 December volcanism continued at an elevated level, with continued growth of the lava dome. Seismic activity was comparable to the previous week. Rockfalls were observed cascading down the E and S faces of the dome and new rockfall deposits were seen on the E side of the volcano in the upper portion of Tar River Valley. The crest of the lava dome was still dominated by a lava spine as it has been for several months.

Source: Montserrat Volcano Observatory (MVO)


22 November-28 November 2000

The MVO reported that during 17-24 November volcanism continued at an elevated level, with the continued growth of the lava dome and a significant increase in the number of detected rockfall signals. The latter parameter more than doubled relative to the previous week. On the other hand, the number and energy of long-period earthquakes decreased. The lava spine that was growing on top of the lava dome was estimated at over 1,085 m a.s.l. on 17 November, but partially collapsed sometime during 18-19 November. Rockfalls and small pyroclastic flows traveled down the notch between the NE and N lobes of the 1995-98 dome. Ash clouds associated with this activity reached no higher than 3 km a.s.l. Towards the end of the week rockfall activity down the E flank decreased. The Washington VAAC reported low-level ash clouds visible during the week; these traveled to the NW and WNW.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


15 November-21 November 2000

The MVO reported that during 10-17 November, volcanism continued at an elevated level, with the continued growth of the lava dome on the eastern side of the summit region. The level of seismicity was higher than in the previous week, with a marked increase in the number of long-period earthquakes. The lava dome was still dominated by the extrusion of a large lava spine that had an altitude of 1,059 m a.s.l. on 12 November, and 1,077 m a.s.l. by 13 November, which was the greatest height that had been measured throughout the eruption. The spine appeared to be even taller on 17 November, but a direct measurement was not possible. The number of rockfalls and pyroclastic flows increased towards the end of the week. On 15 November a small pyroclastic flow traveled ~1 km to the NW down Tyre's Ghaut. On 17 November pyroclastic-flow deposits were noted in the upper reaches of Tuitt's and White Ghauts on the NE side of the volcano. This represented the first new dome material to have traveled down the notch between the NE and N lobes of the 1995-98 dome. Most rockfall activity occurred across the E face of the dome above Tar River. Ash clouds produced from pyroclastic flows and rockfalls did not exceed 3 km a.s.l and mostly traveled to the W across the exclusion zone. Many of the low-level ash clouds were visible in GOES-8 imagery during the week.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)


8 November-14 November 2000

The MVO reported that during 3-10 November, volcanism continued at an elevated level and seismicity was slightly higher than the previous week. Dome growth continued and rockfalls occurred on the E side of the crater. Heavy rainfall on 4 and 8 November produced mudflows that traveled to the NW down the Belham River. During the 8 November rainfall, continuous rockfalls and low-energy pyroclastic flows traveled to the E down the Tar River valley. The pyroclastic flows generated ash clouds that rose to ~2 km a.s.l. and were blown to the N. On 13 November the Washington VAAC reported that a low-level (~1.5 km a.s.l.) ash plume that was blown to the N was visible in GOES-8 imagery.

Source: Montserrat Volcano Observatory (MVO)


1 November-7 November 2000

The MVO reported that during 27 October-3 November, volcanism continued at an elevated level at Soufriere Hills and seismicity was slightly lower than it had been the previous week. Observations revealed that the lava dome within the summit crater continued to grow only on the E side of the crater. Toppled fragments of a spine that grew on top of the dome had a maximum elevation of 1,013 m a.s.l. Rockfalls, which were restricted to the E side of the dome, produced small ash clouds that drifted to the NW and deposited very light ash in populated areas of Montserrat.

Source: Montserrat Volcano Observatory (MVO)


Summary of eruption dates and Volcanic Explosivity Indices (VEI).

Start Date Stop Date Eruption Certainty VEI Evidence Activity Area or Unit
2005 Apr 15 2013 Feb 11 (continuing) Confirmed 3 Historical Observations
2004 Mar 3 2004 May 2 Confirmed 3 Historical Observations
1995 Jul 18 2003 Oct 8 Confirmed 3 Historical Observations
1630 ± 50 years Unknown Confirmed   Radiocarbon (uncorrected) Castle Peak
2000 BCE ± 75 years Unknown Confirmed   Radiocarbon (uncorrected) English's crater

The following references are the sources used for data regarding this volcano. References are linked directly to our volcano data file. Discussion of another volcano or eruption (sometimes far from the one that is the subject of the manuscript) may produce a citation that is not at all apparent from the title. Additional discussion of data sources can be found under Volcano Data Criteria.

Baker P E, 1985. Volcanic hazards on St. Kitts and Montserrat, West Indies. J Geol Soc London, 142: 279-295.

Baxter P J, Boyle R, Cole P, Neri A, Spence R, Zuccaro G, 2005. The impact of pyroclastic surges on buildings at the eruption of the Soufriere Hills volcano, Montserrat. Bull Volc, 67: 292-313.

Belousov A, Voight B, Belousov M, 2007. Directed blasts and blast-generated pyroclastic density currents: a comparison of the Bezymianny 1956, Mount St Helens 1980, and Soufriere Hills, Montserrat 1997 eruptions and deposits. Bull Volc, 69: 701-740.

Carn S A, Watts R B, Thompson G, Norton G E, 2004. Anatomy of a lava dome collapse: the 20 March 2000 event at Soufriere Hills volcano, Montserrat. J Volc Geotherm Res, 131: 241-264.

Chiodini G, Cioni R, Frullani A, Guidi M, Marini L, Prati F, Raco B, 1996. Fluid geochemistry of Montserrat Island, West Indies. Bull Volc, 58: 380-392.

Deplus C, Le Friant A, Boudon G, Komorowski J-C, Villemant B, Harford C, Segoufin J, Cheminee J-L, 2001. Submarine evidence for large-scale debris avalanches in the Lesser Antilles arc. Earth Planet Sci Lett, 192: 145-157.

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The complex, dominantly andesitic Soufrière Hills volcano occupies the southern half of the island of Montserrat. The summit area consists primarily of a series of lava domes emplaced along an ESE-trending zone. English's Crater, a 1-km-wide crater breached widely to the east, was formed during an eruption about 4000 years ago in which the summit collapsed, producing a large submarine debris avalanche. Block-and-ash flow and surge deposits associated with dome growth predominate in flank deposits. Non-eruptive seismic swarms occurred at 30-year intervals in the 20th century, but with the exception of a 17th-century eruption that produced the Castle Peak lava dome, no historical eruptions were recorded on Montserrat until 1995. Long-term small-to-moderate ash eruptions beginning in that year were later accompanied by lava-dome growth and pyroclastic flows that forced evacuation of the southern half of the island and ultimately destroyed the capital city of Plymouth, causing major social and economic disruption.