Karangetang [Api Siau]

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  • Volcanic Region
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  • Last Known Eruption
  • 2.78°N
  • 125.4°E

  • 1784 m
    5852 ft

  • 267020
  • Latitude
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Most Recent Weekly Report: 15 October-21 October 2014


Based on analyses of satellite imagery and wind data, the Darwin VAAC reported that on 20 October ash plumes from Karangetang rose to an altitude of 3 km (10,000 ft) a.s.l. and drifted 75 km NW.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)


Most Recent Bulletin Report: January 2014 (BGVN 39:01)


2011 into 2014: Spatter at crater, lava flows, and ash plumes

Our last Bulletin report (BGVN 36:01), covered the interval from 6 August 2010 to late-March 2011. This report covers activity for 21 March 2011 through 9 February 2014. During this interval, eruptions clearly took place in March and April 2011, in May 2012, and in April 2013. Crater glow was seen in July, and again during late August to early September 2013, suggesting eruptions. The next report came 9 February 2014, again indicating an eruption then. MODVOLC data discussed at the end also supplements this eruptive information. Highlights include several episodes of abundant alerts and several intervals with pauses, including a 10 month pause that ended on 17 May 2012.

2011. The Center of Volcanology and Geological Hazard Mitigation (CVGHM) reported that during 21-23 March incandescent material from Karangetang was ejected 50-75 m above the crater. Lava flows traveled as far as 2 km and collapses from the lava-flow fronts generated avalanches that moved down the flanks at most another 300 m. On 24 March lava was incandescent in areas 1.5 km away from the crater. Incandescent material from the lava-flow fronts rolled an additional 200-500 m down the flanks. Incandescent material was again ejected 75 m above the crater. Later that day, due to decreased seismicity and a decline in the rate of lava flows, the Alert Level was lowered to 3 (on a scale of 1-4).

CVGHM reported that during 30-31 March incandescence emanated from Karangetang's main crater as well as bluish and white gas plumes. Lava flows originating from the main crater traveled 2 km down the flanks. Incandescent avalanches from the main crater and from the lava-flow fronts traveled up to 1.8 km down the flanks. On 31 March a thunderous sound was accompanied by a gray plume that rose 200 m above the crater. The Alert Level remained at 3 (on a scale of 1-4). During 1 May and at least into August, lava flows remained active. News indicated 600 people evacuated in August.

2012. Based on analyses of satellite imagery, the Darwin Volcanic Ash Advisory Centre (VAAC) reported that on 14 May 2012 an ash plume rose to 3.7 km a.s.l. and drifted 130 km SE. On 16 May an ash plume again rose to an altitude of 3.7 km a.s.l. then drifted about 110 km SE. The VAAC also described a 16 December ash plume to an altitude of 3.7 km drifting 110 km SE.

2013. Based on analyses of satellite imagery and wind data, the Darwin VAAC reported that on 9 April an ash plume rose to an altitude of 4.3 km a.s.l. and drifted over 45 km WNW. According to a (Kompas) news article, pahoehoe lava flows traveled 150 m and rock avalanches traveled 2 km on that same day.

Based on reports from the observation post in Salili, CVGHM stated on 26 July that the occurrence of rock avalanches descending Karangetang's flanks decreased during 2013; the last one occurred on 7 July, and traveled 2 km down the Batuawang and Kahetang (E) drainages. Although fog often prevented visual observations, white plumes were sometimes seen rising up to 500 m from two craters. Incandescence from the lava dome was reflected in the plume at night. Seismicity fluctuated, but signals indicating avalanches declined. Based on the cessation of avalanches, visual observations, and decreasing seismicity, the Alert Level was lowered to 2 (on a scale of 1-4) on 26 July.

Based on observations from the post in Salili, CVGHM reported that although Karangetang was sometimes covered in fog during 1 August-2 September white plumes were seen rising up to 500 m above the main crater and up to 300 m above Crater II. Incandescence from the crater was often observed at night. Avalanches began traveling down the Batuawang drainage on 2 September and then intensified the next day. The Alert Level was raised to 3 (on a scale of 1-4) on 3 September.

2014. Based on analyses of satellite imagery and wind data, the Darwin VAAC reported that on 9 February an ash plume rose to an altitude of 4.3 km a.s.l. and drifted over 80 km W.

MODVOLC thermal alerts. In BGVN 36:01 we reported thermal alerts derived from the Hawai'i Institute of Geophysics and Planetology Thermal Alerts System (MODVOLC), discussing the presence or absence of thermal alerts through the last available posted alert, 12 March 2011. During this report's duration, the alerts sometimes continued and were typically abundant, usually on the order of one or more per week or two, but in some cases several alerts per day, until pausing after 15 May 2011. They resumed during the days 8 and 13 August 2011 and then stopped.

When the alerts resumed on 17 May 2012, they had undergone a pause of 10 months. Alerts were again abundant during 17 May until 18 June 2012. A pause ensued until 9 September 2012 and the alerts were common until 26 January 2013. The subsequent pause ended and alerts resumed during 4 April-5 June 2013. The subsequent pause took place during 6 June-2 September 2013, and then the pause ended with a few alerts during 3-5 September 2013 but an absence of alerts for the remainder of 2013. When checked on 1 July 2014, only one alert for 2014 had been posted: 8 June 2014.

Information Contacts: Center of Volcanology and Geological Hazard Mitigation (CVGHM), Jalan Diponegoro 57, Bandung 40122, Indonesia (URL: http://portal.vsi.esdm.go.id/joomla/); Darwin Volcanic Ash Advisory Centre (VAAC), Bureau of Meteorology, Northern Territory Regional Office, PO Box 40050, Casuarina, NT 0811, Australia (URL: http://www.bom.gov.au/info/vaac/); Kompas (URL: http://nasional.kompas.com/read/2013/04/09/08311241/Guguran.Lava.Karangetang.Hingga.2.km ) and Hawai'i Institute of Geophysics and Planetology (HIGP) MODVOLC Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://hotspot.higp.hawaii.edu/).

Index of Weekly Reports


2014: February | September | October
2013: April | July | August
2012: May | December
2011: March | June | August
2010: February | August | September | December
2009: May | June | October | November
2008: March | October | November
2007: February | March | April | June | August | October
2006: June | July | August | November
2005: February | May | July | August | October
2003: January | February | March | April | May | July | October
2002: January | February | March | May | June | July | October | November
2001: January | February | April | May | July | August | September | October | November
2000: November | December

Weekly Reports


15 October-21 October 2014

Based on analyses of satellite imagery and wind data, the Darwin VAAC reported that on 20 October ash plumes from Karangetang rose to an altitude of 3 km (10,000 ft) a.s.l. and drifted 75 km NW.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)


17 September-23 September 2014

PVMBG reported that although Karangetang was often covered in fog during 7-14 September, observers occasionally noted white plumes rising at most 150 m from the main crater and Crater II. Incandescence from the lava dome was observed at night. Seismicity remained high and was dominated by shallow earthquakes from lava-dome growth and avalanches. The Alert Level remained at 3 (on a scale of 1-4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


5 February-11 February 2014

Based on analyses of satellite imagery and wind data, the Darwin VAAC reported that on 9 February an ash plume from Karangetang rose to an altitude of 4.3 km (14,000 ft) a.s.l. and drifted over 80 km W.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)


28 August-3 September 2013

Based on observations from the post in Salili, CVGHM reported that, although Karangetang was sometimes covered in fog during 1 August-2 September, white plumes were seen rising as high as 500 m above the main crater and as high as 300 m above Crater II. Incandescence from the crater was often observed at night. Avalanches began traveling down the Batuawang drainage on 2 September and then intensified the next day. The Alert Level was raised to 3 (on a scale of 1-4) on 3 September.

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


24 July-30 July 2013

Based on reports from the observation post in Salili, CVGHM stated on 26 July that the occurrence of rock avalanches descending Karangetang’s flanks decreased during 2013; the last one occurred on 7 July, and traveled 2 km down the Batuawang and Kahetang (E) drainages. Although fog often prevented visual observations, white plumes were sometimes seen rising up to 500 m from two craters. Incandescence from the lava dome was reflected in the plume at night. Seismicity fluctuated, but signals indicating avalanches declined. Based on the cessation of avalanches, visual observations, and decreasing seismicity, the Alert Level was lowered to 2 (on a scale of 1-4) on 26 July.

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


3 April-9 April 2013

Based on analyses of satellite imagery and wind data, the Darwin VAAC reported that on 9 April an ash plume from Karangetang rose to an altitude of 4.3 km (14,000 ft) a.s.l. and drifted over 45 km WNW. According to a news article, pahoehoe lava flows traveled 150 m and rock avalanches traveled 2 km down the flanks on that same day.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)


12 December-18 December 2012

Based on analyses of satellite imagery and wind data, the Darwin VAAC reported that on 16 December an ash plume from Karangetang rose to an altitude of 3 km (10,000 ft) a.s.l. and drifted 110 km SW.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)


9 May-15 May 2012

Based on analyses of satellite imagery, the Darwin VAAC reported that on 14 May an ash plume from Karangetang rose to an altitude of 3.7 km (12,000 ft) a.s.l. and drifted 130 km SE. On 16 May an ash plume again rose to an altitude of 3.7 km (12,000 ft) a.s.l. then drifted about 110 km SE.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)


3 August-9 August 2011

CVGHM reported that during July and August cloud cover often prevented observations of Karangetang, although white smoke was sometimes observed rising as high as 500 m above the crater. At night incandescence up to 10 m was often observed.

On 8 July a phreatic eruption occurred from the N part of the Main Crater, ejecting material 150 m high. On 24 July and 1 August incandescent material traveled 1,500 m from the Main Crater. Sounds indicating an eruption were heard on 7 August, although fog prevented observations of the crater. Based on recent visual observations and increased seismicity, the Alert Level was raised to 3 (on a scale of 1-4) on 8 August. According to a news article, about 600 people living on the flanks evacuated.

Sources: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM); Herald Sun


1 June-7 June 2011

CVGHM reported that during 25 March-5 June seismic activity at Karangetang decreased along with the potential threat of avalanches and pyroclastic flows. During 1 May-5 June no pyroclastic flows were observed. Lava flowed 200 m down the flanks and produced incandescent material from the flow fronts that traveled an additional 1.5-1.8 km. Bluish-white emissions rose as high as 500 m from the main crater and incandescence from the crater was observed at night. Lava flow and avalanche activity decreased on 19 May. The Alert Level was lowered to 2 (on a scale of 1-4) on 6 June.

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


30 March-5 April 2011

CVGHM reported that during 30-31 March incandescence emanated from Karangetang's main crater as well as bluish and white gas plumes. Lava flows originating from the main crater traveled 2 km down the flanks. Incandescent avalanches from the main crater and from the lava-flow fronts traveled up to 1.8 km down the flanks. On 31 March a thunderous sound was accompanied by a gray plume that rose 200 m above the crater. The Alert Level remained at 3 (on a scale of 1-4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


23 March-29 March 2011

CVGHM reported that during 21-23 March incandescent material from Karangetang was ejected 50-75 m above the crater. Lava flows traveled as far as 2 km and collapses from the lava-flow fronts generated avalanches that moved down the flanks up to 300 m further. On 24 March lava was incandescent in areas 1.5 km away from the crater. Incandescent material from the lava-flow fronts rolled an additional 200-500 m down the flanks. Incandescent material was again ejected 75 m above the crater. Later that day, due to decreased seismicity and a decline in the lava-flow effusion rate, the Alert Level was lowered to 3 (on a scale of 1-4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


16 March-22 March 2011

CVGHM reported that on 11 March the Alert Level for Karangetang was raised from 2 to 3 (on a scale of 1-4) due to increased seismicity. During 12-16 March when the weather was clear, bluish gas plumes rose 50-150 m above the main crater. On 17 March lava flows traveled as far as 2 km from the main crater, accompanied by roaring and booming noises.

On 18 March lava flows traveled 1.5 km and collapses from the lava flow fronts generated avalanches that moved another 500 m. Avalanches from the crater traveled 3.8 km down the flanks. Multiple pyroclastic flows about 1.5 km long destroyed a bridge, damaged a house, and trapped 31 people between the flow paths who were later evacuated. Later that day pyroclastic flows traveled 4 km, reaching the shore. The Alert Level was raised to 4. On 20 March lava flows traveled 1.8 km and avalanches from the lava flow fronts again went 500 m. Incandescent material rolled 1.5 km down the flanks and pyroclastic flows traveled 2.3 km from the crater. According to news articles, 600-1,200 people were evacuated from villages on the W flank.

Sources: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM); Straits Times; CNN


9 March-15 March 2011

Based on analyses of satellite imagery, the Darwin VAAC reported that on 11 March an ash plume from Karangetang rose to an altitude of 2.4 km (8,000 ft) a.s.l. and drifted 55 km SW. According to news reports, lava flows at the summit were visible on 11 March. Blocks originating from the lava dome traveled as far as 2 km down the flanks. Hot gas clouds also descended the flanks. The VAAC also noted that on 13 March an ash plume rose to an altitude of 3.7 km (12,000 ft) a.s.l. and drifted 37 km.

Sources: Darwin Volcanic Ash Advisory Centre (VAAC); Okezone; Novinite


8 December-14 December 2010

CVGHM reported that during November until 12 December observers at the station at Salili, S of the volcano, noted a drastic decrease in the occurrence of pyroclastic flows on Karangetang's flanks. Seismicity also decreased, and white plumes rose up to 300 m above the craters. The Alert Level was lowered to 2 (on a scale of 1-4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


22 September-28 September 2010

CVGHM reported that during 1-7 September lava seen from the observation post (5 km SSW) traveled 75 m down Karangetang's flanks. Avalanches traveled as far as 1.5 km down the Batang (S), Batu Awang (E), and Nanitu drainages. Incandescent material was ejected 350 m above the crater. During 8-21 September lava traveled 500 m down the flanks. Avalanches originating from the end of the lava flow traveled as far as 2 km down the Batang, Kahetang (E), and Nanitu drainages. During 18-20 September material was ejected 300-500 m above the crater. Ashfall was reported in areas to the NW. On 21 and 22 September incandescent material traveled down multiple drainages. Strombolian activity was observed on 22 September; material ejected 50 m high fell back down around the crater. That same day the Alert level was raised to 3 (on a scale of 1-4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


4 August-10 August 2010

According to news articles, an eruption from Karangetang on 6 August produced pyroclastic flows on the W flank that destroyed at least seven houses. A hot ash plume rose above the crater, and incandescent material was ejected from the crater and descended multiple flanks. At least four people were missing, five were injured, and about 65 were evacuated. An article also stated that CVGHM raised the Alert Level to 3 (on a scale of 1-4). According to reports from CVGHM and analyses of satellite imagery, the Darwin VAAC reported that an ash plume rose to an altitude of 9.1 km (30,000 ft) a.s.l. and drifted W.

Sources: Darwin Volcanic Ash Advisory Centre (VAAC); CNN; Associated Press


10 February-16 February 2010

On 12 February, CVGHM reported that seismicity from Karangetang declined during 1 January-8 February. When the weather was clear, white plumes were seen rising 100-200 m above the crater rim. Incandescent material was ejected 10-50 m above the Utama Crater. Based on these observations and the decline in seismicity, CVGHM lowered the Alert level to 2 (on a scale of 1-4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


4 November-10 November 2009

According to news articles, a pyroclastic flow and a lahar descended the flanks of Karangetang on 4 November. Residents saw active lava flows the next day. On 11 November, incandescent material was ejected 5 m into the air.

Sources: Manado Post; Berita News


28 October-3 November 2009

Based on a pilot observation and analyses of satellite imagery, the Darwin VAAC reported that on 3 November an ash plume from Karangetang rose to an altitude of 3 km (10,000 ft) a.s.l. and drifted 90-185 km W.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)


3 June-9 June 2009

CVGHM reported that during 1-6 June lava flows from Karangetang traveled 50 m E and 600 m SE. Incandescent rocks, from the main craters and ends of the lava flows, traveled as far as 2 km towards multiple river valleys, including the Keting River to the S. On 1 June, white-to-gray-to-brownish plumes rose 700 m above the main crater. Incandescent lava was ejected 500-700 m. On 4 June, tremor amplitude and the number of earthquakes decreased. During 4-6 June, white plumes rose 50-300 m from the main crater. On 7 and 8 June, fog often prevented observations and incandescent rocks were rarely seen. The Alert Level was lowered to 3 (on a scale of 1-4) on 9 June.

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


27 May-2 June 2009

CVGHM reported that seismicity from Karangetang increased during 30-31 May and tremor was detected. On 30 May, diffuse white plumes rose 10-50 m high and incandescence was seen at the crater. On 31 May, white emissions from Utama Crater in the N part of the summit region rose 100 m. Incandescent material traveled as far as 2.3 km, mostly down the S flank. Ash plumes that rose 25-700 m were accompanied by thunderous sounds. The Alert Level was raised to 4, the highest level on a scale of 1-4. People were advised not to go within a 3-km-radius of the active area. According to a news article, over 350 people evacuated the area.

Sources: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM); Xinhua


20 May-26 May 2009

Based on a pilot observation, the Darwin VAAC reported that on 24 May an ash plume from Karangetang rose to an altitude of 3.7 km (12,000 ft) a.s.l. and drifted 75 km S.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)


26 November-2 December 2008

CVGHM reported that on 28 November seismicity from Karangetang increased and indicated rockfalls. White plumes rose from summit craters I and II to approximate altitudes of 1.8-2.2 km (5,900-7,200 ft) a.s.l. On 29 November white and brownish plumes rose to an altitude of 1.8 km (5,900 ft) a.s.l. Incandescent rockslides from the main crater traveled 250 m S towards the Bahembang River, 250 m W towards the Beha Timur River, and 500-1,000 m S towards the Keting River. Thunderous noises were reported. On 30 November, fog prevented visual observations; the seismic network recorded 160 rockfalls. On 1 December, incandescent rockslides traveled 250 m S towards the Bahembang River, 750 m W towards the Beha Timur River, and 500-1,500 m S towards the Keting River. On 2 December, the Alert Level was raised to 3 (on a scale of 1-4) due to the continuation of elevated seismicity, run-out distances of incandescent rockslides, and height of incandescent material ejected from the summit.

Based on analysis of satellite imagery and information from CVGHM, the Darwin VAAC reported that on 2 December an ash plume from Karangetang rose to an altitude of 3 km (10,000 ft) a.s.l. and drifted W.

Sources: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM); Darwin Volcanic Ash Advisory Centre (VAAC)


1 October-7 October 2008

Based on analysis of satellite imagery, the Darwin VAAC reported that on 4 October a possible eruption from Karangetang generated a plume that rose to an altitude of 12.2 km (40,000 ft) a.s.l.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)


5 March-11 March 2008

Based on a pilot observation, the Darwin VAAC reported a possible low-level ash plume on 12 March.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)


17 October-23 October 2007

Based on a pilot report, the Darwin VAAC reported that a plume from Karangetang rose to an altitude of 1.5 km (5,000 ft) a.s.l. on 21 October. A plume was not detected on satellite imagery due to cloud cover.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)


10 October-16 October 2007

Based on a pilot report, the Darwin VAAC reported that an ash plume from Karangetang rose to an altitude of 1.9 km (6,200 ft) a.s.l. on 13 October.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)


29 August-4 September 2007

The Alert Status of Karangetang was lowered on 30 August from 4 to 3 (on a scale of 1-4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


15 August-21 August 2007

The Alert Status of Karangetang was raised on 18 August from 3 to 4 (on a scale of 1-4) due to increased eruptive activity, based on visual observation and increased seismicity. According to news articles, lava flowed about 1 km down the S slope and "booming" noises were heard. Thick ashfall covered villages, farms, and trees on the slopes.

Sources: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM); The Jakarta Post; Reuters; Agence France-Presse (AFP)


8 August-14 August 2007

The Alert Status of Karangetang was raised on 11 August from 2 to 3 (on a scale of 1-4) due to increased eruptive activity. Tremors increased during 5-8 August. According to news articles, lava and pyroclastic flows that were observed on 10 August, prompted authorities to evacuate more than 500 people from villages on the slopes. During the reporting period, a lava fountain rose 25-75 m above the summit.

Sources: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM); News.com.au - News Limited


20 June-26 June 2007

Based on visual observations, CVGHM reported that during 18-25 June ash plumes from Karangetang's main crater produced plumes that rose to an altitude of 2 km (6,600 ft) a.s.l. Activity at Crater II consisted of diffuse ash plumes that rose to an altitude of 1.8 km (5,900 ft) a.s.l. and incandescent ash that rose about 10 m. The Alert Level remained at 2 (on a scale of 1-4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


4 April-10 April 2007

CVGHM reported that sometime between mid-March and 6 April, the lava dome in the northern of three craters at Karangetang collapsed and was replaced by a new dome.

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


28 March-3 April 2007

According to a news article, eruption plumes from Karangetang rose to an altitude of 1.9 km (6,000 ft) a.s.l. on 27 March. Pyroclastic flows may have occurred the next day.

Source: The Jakarta Post


14 February-20 February 2007

On 14 February, the Alert Level at Karangetang was lowered to 2 (scale of 1-4). Seismicity had decreased in intensity and frequency since 18 November 2006. Lava flows and incandescent avalanches were not observed after 25 January 2007.

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


22 November-28 November 2006

According to the Darwin VAAC, an eruption at Karangetang on 24 November produced a small ash plume observed on satellite imagery that reached an altitude of 3 km (10,000 ft) a.s.l.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)


9 August-15 August 2006

During 7-13 August, lava flows from Karangetang advanced E toward the Batu Awang river. Incandescent rockfalls originating from lava flow fronts were also observed. The Alert Level remained at 3.

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


2 August-8 August 2006

On 2 August, the Alert Level at Karangetang was raised to 4, the highest level. During 1-5 August, white plumes reached heights of 50-300 m (164-984 ft) above the summit (6,000-6,800 ft a.s.l.). Lava flows advanced hundreds of meters to over a kilometer E toward the Batu Awang river and S towards the Keting river during the reporting period. Incandescent rockfalls originating from the summit and ends of the lava flows traveled hundreds of meters E toward the Kahetang and Batu Awang rivers and S towards the Keting and Batang rivers. On 5 August, the Alert level was lowered to 3.

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


26 July-1 August 2006

Fog limited clear views of summit activity at Karangetang during the reporting period. Lava flows were observed during 27-31 July moving E toward the Kahetang and Batu Awang rivers at a maximum distance of ~750 m from the vent. Rockfalls traveled up to 2 km towards the Keting River. On 31 July, gas plumes reached a maximum height of 200 m above the summit (or ~6,500 ft a.s.l.).

According to news reports, between 3,000 and 4,000 people from five villages were evacuated on 27 and 28 July due to advancing lava flows and reports of lahars. The news also noted that on 29 July, about 1,300 people remained in shelters.

Sources: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM); Agence France-Presse (AFP); Jaknews


19 July-25 July 2006

The Alert Status of Karangetang was raised on 22 July from 3 to 4 (on a scale of 1-4) due to a further increase in eruptive activity since the last reporting period. On 20 July, lava flows were observed moving E toward the Kahetang and Batu Awang rivers at a maximum distance of 1.8 km from the vent, towards the Keting river at unknown location and distance, and S towards the Bahembang river at a maximum distance of 2 km. On 21 July, a pyroclastic flow originating from the upper S flank traveled 2.5 km toward the Stone river (unknown direction) and was followed by lava flows that traveled toward the Keting river and E towards the Kahetang river at a maximum distance of 2 km. A "thin white smoke" was seen at a height of ~350 m above the summit (7,000 ft a.s.l.). Lava flows traveled a maximum distance of ~2.3 km towards the Keting river and S towards the Bahembang river during 22-23 and 25 July.

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


12 July-18 July 2006

The Alert Status of Karangetang was raised on 13 July from 2 to 3 (on a scale of 1-4) due to increased eruptive activity. On 12 July, lava flows were observed moving E toward the Kahetang and Batu Awang rivers at a maximum distance of 2 km from the vent. White emissions reached a height of 600 m above the crater (7,800 ft a.s.l.).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


28 June-4 July 2006

According to the Darwin VAAC, a small eruption at Karangetang on 3 July produced an ash plume observed on satellite imagery that reached an altitude of 3.7 km (12,000 ft) a.s.l.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)


12 October-18 October 2005

Gas was emitted from Karangetang's North and Batukole craters during 10-16 October. Seismicity was dominated by multiphase events, which decreased in number in comparison to the previous week. The number of deep volcanic earthquakes increased. Karangetang remained at Alert Level 3 (on a scale of 1-4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


5 October-11 October 2005

Gas was emitted from Karangetang's South and Batukole craters during 26 September to 9 October. Seismicity was dominated by multiphase events, with more occurring than during the previous week. The number of deep volcanic and shallow volcanic earthquakes decreased. Karangetang remained at Alert Level 3 (on a scale of 1-4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


3 August-9 August 2005

Satellite imagery showed an ash cloud from Karangetang on 5 August at a height of 4.6 km (~15,000 ft) a.s.l.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)


27 July-2 August 2005

Satellite imagery showed an ash cloud from Karangetang on 2 August at a height of 4.6 km (~15,000 ft) a.s.l.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)


25 May-31 May 2005

Based on a pilot observation, the Darwin VAAC reported that ash from Karangetang was at a height below 3 km (10,000 ft) a.s.l. drifting E on 30 May. Ash was not visible on satellite imagery.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)


23 February-1 March 2005

Lava avalanches continued at Karangetang during 25-27 February, traveling 500-1,200 m down the drainages of Kali Beha, Kali Kahetang, Kali Batuawan, and Kali Nanitu. Seismicity was dominated by avalanche earthquakes. Karangetang remained at Alert Level 3 (on a scale of 1-4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


16 February-22 February 2005

DVGHM reported that on 16 February, a lava flow traveled 600 m from Karangetang's crater towards Kali Nanitu. Lava avalanches in the same area traveled as far as 1,200 m down the volcano's flank. At 1830 that day a pyroclastic flow traveled ~3,400 m, reaching the sea. Karangetang remained at Alert Level 3 (on a scale of 1-4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


2 February-8 February 2005

Lava avalanches from the fronts of lava flows occurred at Karangetang during 26 January to at least 30 January. The avalanches traveled towards several rivers; Beha Barat (750-1,200 m), Batu Awan (750-2,200 m), and Kahetang (1750 m). Karangetang was at Alert Level 3 (on a scale of 1-4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


8 October-14 October 2003

During 1-28 September, gas emissions rose 150-350 m above Karangetang's South Crater and incandescence was seen extending ~25 m above the crater. Also, gas emissions rose 50-150 m above North Crater. No lava avalanches occurred during the report period. Karangetang remained at Alert Level 2 (on a scale of 1-4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


16 July-22 July 2003

Based on an aircraft report, the Darwin VAAC stated that a thick ash plume was visible above Karangetang at a height of ~7.5 km a.s.l. Ash was not visible on satellite imagery.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)


2 July-8 July 2003

During 2-29 June, volcanic activity continued at Karangetang at moderate levels, with low-level ash plumes rising above South Crater and gas emissions from North Crater. During 2-8 June, lava avalanches traveled as far as 1 km toward Batang River. During 9-15 June, lava avalanches traveled as far as 1 km down Beha River and ~250 m toward Batu Awang River. Karangetang remained at Alert Level 2 (on a scale of 1-4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


28 May-3 June 2003

Satellite imagery showed a low-level plume extending NE from Karangetang on 30 May at 0646.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)


21 May-27 May 2003

A reduction in volcanic activity at Karangetang during 12-18 May led VSI to reduce the Alert Level from 3 to 2. Activity during the week consisted of low-level ash clouds rising above Karangetang's South crater, incandescence extending 25 m above the crater, and incandescent avalanches traveling toward Kali Batang to runout distances of 750-1,000 m. In addition, there was a decrease in the number of multiphase earthquakes compared to the previous week.

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


7 May-13 May 2003

On 22 April at 1802 an ash explosion occurred at Karangetang that was accompanied by the ejection of incandescent volcanic material. The resultant ash column rose to ~1,750 m above the volcano, and incandescent material was ejected to ~750 m above the volcano. Ash was deposited on the volcano's W slope, including in the villages of Lehi, Mini, Kinali, and Hiung. The explosion was followed by lava avalanches to the W and S and pyroclastic flows toward Batang River to a runout distance of 2,250 m. Another explosion occurred on 24 April that produced an ash cloud to ~750 m above the volcano. Generally, during 21 April to 4 May, low-level ash plumes rose above South Crater, and glowing was seen up to 25 m above the crater. Karangetang remained at Alert Level 3 (on a scale of 1-4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


16 April-22 April 2003

Karangetang's S crater gave off ash emissions that reached 250 m high during the week of 16-22 April. Just prior, on 15 April, an explosion that sounded like a blast was followed by lava avalanches traveling S and W and reaching ~1 km from their source at S crater. The resulting dark-gray ash column reached 1.5 km above the crater. Ash fell around Dame and Karalung villages, some fell into the sea on the E. Another similar explosion occurred on 20 April, but it generated a pyroclastic flow that extended 2.5 km in length. Blasting noises were audible for ~3 minutes. Seismic records suggested 32 explosion events, 226 multiphase earthquakes, and 26 emission earthquakes. Karangetang=s hazard status was at level 3 (out of a possible 4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


2 April-8 April 2003

During 24-30 March, Karangetang's South Crater generated low-level "white-gray ash emissions" and incandescence visible to 25 m above the crater. There was a significant decrease in the number of earthquakes. The Alert Level at Karangetang remained at 3 (on a scale of 1-4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


26 March-1 April 2003

During 17-23 March, Karangetang's South Crater generated low-level "white-gray ash emissions" and incandescence visible to 25 m above the crater. In addition, incandescent lava avalanches traveled down the volcano's flanks. During the report period, there was a significant increase in the number of volcanic and multiphase earthquakes. The Alert Level at Karangetang remained at 3 (on a scale of 1-4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


19 March-25 March 2003

During 10-16 March, Karangetang's South crater generated low-level "white-gray ash emissions" and incandescence visible to 50 m above the crater. Incandescent lava avalanches traveled toward Kahetang, Batuawang, Batang, and Beha rivers. During the report period, there was a decrease in the number of earthquakes, and seismicity was dominated by 125 avalanche earthquakes. The Alert Level at Karangetang remained at 3 (on a scale of 1-4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


5 March-11 March 2003

During 24 February to 2 March, volcanic activity at Karangetang's South crater consisted of "white-gray ash emissions" rising to low levels, incandescent glow extending to 50 m above the crater, and a booming noise that was heard from the observatory post. During the report period, there was an increase in the number of shallow volcanic earthquakes, while the number of multiphase earthquakes decreased. Karangetang remained at Alert Level 3 (on a scale of 1-4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


5 February-11 February 2003

Volcanic activity at Karangetang during 3-9 February consisted of low-level ash clouds rising above South and North craters, incandescent glow extending to 50 m above South Crater, and booming noises that were heard at the observation post. On 6 February at 0027 an ash explosion produced a cloud to an unknown height that deposited ash in villages SW of the volcano, including Akesembeka, Tarurane, Tatahadeng, Bebali, and Salili. During the report week, there was a significant increase in volcanic and emission earthquakes in comparison to the previous week. Karangetang remained at Alert Level 3 (on a scale of 1-4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


22 January-28 January 2003

Moderate volcanic activity continued at Karangetang during 13-26 January. Low-level ash plumes rose above North and South craters, incandescent glow rose to 50 m above the crater, and booming noises were sometimes heard at the observation post. On 14 January two ash explosions occurred at South crater, ejecting incandescent material that fell up to 50 m around the crater. Some of the material traveled as far as 200 m into the Beha River. An ash column rose to 300 m and ash fell into the E part of the sea. Karangetang remained at Alert Level 3 (on a scale of 1-4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


27 November-3 December 2002

Volcanic activity at Karangetang during 19-24 November consisted of low-level ash plumes rising above South and North craters. In addition, there was a significant increase in the number of volcanic earthquakes in comparison to the previous week. Karangetang remained at Alert Level 3 (on a scale of 1-4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


30 October-5 November 2002

During 21-27 October, low-level plumes continued to rise above Karangetang's South and North craters. Weak-to-strong thundering sounds emanated from the volcano frequently. Seismicity was dominated by emission earthquakes and there was an increase in the number of volcanic earthquakes in comparison to the previous week. Karangetang remained at Alert Level 3 (on a scale of 1-4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


16 October-22 October 2002

During 7-14 October, VSI raised the Alert Level at Karangetang from 2 to 3. During this period, a thick ash plume rose ~400 m above South Crater and incandescent lava avalanches traveled ~250 m toward Nanitu River and ~400 m W toward Beha River. Also, a thin ash plume rose ~50 m above North Crater. On 19 October at 1759 an explosion produced an ash cloud to ~750 m above the volcano. The ash cloud drifted N, depositing ash into the sea. In addition, glowing material was ejected 500 m vertically and landed inside the crater. During 14-21 October, lava avalanches continued to travel down Karangetang's flanks and lava flowed 1,500 m toward Nanitu River, 1,000 m toward Beha River, and 750 m E toward Kahetang River.

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


9 October-15 October 2002

Karangetang remained active during 9 September to 6 October, with low-level ash clouds rising above South and North craters, lava flowing from the crater, and volcanic tremor being recorded. The lava flows traveled 25-200 m from the crater rim toward the Nanitu River and as far as 400 m toward Beha River. Karangetang remained at Alert Level 2 (on a scale of 1-4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


31 July-6 August 2002

According to VSI, a small ash plume reached 400 m above the S part of the main crater of Karangetang this week. Crater II produced a small ash plume to 200 m. Seismicity decreased compared to the previous week. Karangetang remained at Alert Level 2 (on a scale of 1-4).

Sources: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM); Darwin Volcanic Ash Advisory Centre (VAAC)


24 July-30 July 2002

According to VSI, on 15 July at 1355 an explosion at Karangetang's main crater produced an ash cloud to a height of 1.5 km above the crater. Ash fell to the N of the volcano. An accompanying lava avalanche traveled up to 1.5 km into Kahetang River Valley. During the rest of 15-21 July, low-level plumes continued to rise above Karangetang's main crater and Crater II. Based on information from a pilot report, the Darwin VAAC reported that a smoke plume was observed on 29 July at 1323 rising to an unknown height. Karangetang remained at Alert Level 2 (on a scale of 1-4).

Sources: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM); Darwin Volcanic Ash Advisory Centre (VAAC)


17 July-23 July 2002

During 8-14 July, volcanic activity increased in comparison to the previous week at Karangetang. On July 8 at 1806 an explosion at the main crater produced an ash cloud that rose 1 km above the crater and drifted to the NNW. Lava was visible flowing down the volcano's W slope and burning crops in its path. During the rest of the report week, low-level plumes continued to rise above Karangetang's main crater and Crater II. Karangetang remained at Alert Level 2 (on a scale of 1-4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


10 July-16 July 2002

During 1-7 July, low-level emissions continued from Karangetang's main crater and Crater II, and a red reflection was visible 25 m above the summit. In addition, seismicity decreased in comparison to the previous week. Karangetang remained at Alert Level 2 (on a scale of 1-4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


3 July-9 July 2002

During 24-30 June, low-level emissions continued from Karangetang's main crater and Crater II, and a red reflection was visible 25 m above the summit. In addition, a large number of shallow and deep volcanic earthquakes continued to occur. Karangetang remained at Alert Level 2 (on a scale of 1-4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


26 June-2 July 2002

During 17-23 June, there was a significant increase in the number of shallow and deep volcanic earthquakes at Karangetang in comparison to the previous week. In addition, low-level plumes rose above the main crater and crater II. A red reflection was visible 25 m above the rim of crater II. Karangetang remained at Alert Level 2 (on a scale of 1-4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


29 May-4 June 2002

During 22 April-26 May, small steam plumes rose 50-500 m above Karangetang's main crater and 10- to 25-m-high "red reflections" were visible above the crater at night. An ash explosion on 12 May at 1116 rose 750 m above the crater and drifted E over the sea. The eruption was followed by lava avalanches that traveled S down the Batu Awang river, and E down the Kahetang river to a maximum run-out distance of ~500 m. Another explosion occurred on 26 May at 1747; it produced an ash cloud to a height of 300 m above the crater that drifted to the W. Karangetang remained at Alert Level 2 (on a scale of 1-4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


27 March-2 April 2002

During 18-24 March, lava avalanches traveled down Karangetang's flanks. On 23 March at 1115 a thunderous sound from the main crater was followed by lava avalanches down the Kahetang and Batu Awang rivers. During the report period, observers noted a thick plume rising 400 m above the crater rim and a 75-m-high "red reflection" rising above the volcano's summit. Seismicity slightly decreased in comparison to the previous week. Karangetang remained at Alert Level 2 (on a scale of 1-4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


6 March-12 March 2002

An eruption that began at Karangetang on 5 March at 1344 produced an ash cloud to a height of ~1.5 km above the volcano's summit. Ash fell to the NE of the volcano. The eruption was accompanied by lava avalanches down the volcano's slopes. After the eruption, a plume of steam and possible ash was seen reaching ~400 m above the crater rim and a "red reflection" extended up to 25 m above the crater. An increase in volcanic and tectonic earthquakes occurred in comparison to the previous week. Karangetang remained at Alert Level 2 (on a scale of 1-4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


27 February-5 March 2002

VSI reported that at Karangetang during 25 February-3 March small volcanic plumes were emitted, a "red reflection" extended 25 m above the crater, and seismicity was high although it decreased in comparison to the previous week. A pilot report to the Darwin VAAC stated that a layer of apparent ash was seen on 5 March at 1544. The layer was located 18.5-37 km from Karangetang at an altitude near 7.5 km (winds in the area suggest ash was at least as high as ~5.5 km). The Karangetang Volcano Observatory reported that an explosion at 1344 the same day rose 1 km above the volcano's summit (2.8 km a.s.l.). No ash was visible in satellite imagery under clear conditions; the ash layer may have been too thin to detect. The volcano remained at Alert Level 2 (on a scale of 1-4).

Sources: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM); Darwin Volcanic Ash Advisory Centre (VAAC)


13 February-19 February 2002

An explosion at Karangetang on 11 February produced an ash cloud and lava flows. The ash cloud drifted to the WSW, depositing 0.5-1 mm of ash in the villages of Kanawong, Lehi, Mimi, Kinali, and Pehe. Incandescent lava flows travelled as far as 1-1.5 km to the W down the Beha River and E down the Kahetang River. Seismicity decreased at the volcano in comparison to the previous week and a "red reflection" was visible at night reaching 25 m above the volcano. Karangetang remained at Alert Level 2 (on a scale of 1-4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


2 January-8 January 2002

During 30 December-6 January multiphase earthquakes continued to be recorded at Karangetang, reflecting the continued growth of the 2001 lava dome. Heavy rain throughout the report period generated a cold 40,000-cubic-meter lahar on 3 January around 1200 that traveled down the Kahetang River. The lahar destroyed two buildings and damaged several homes in Tarurane and Bebali villages. The volcano remained at Alert Level 2 (on a scale of 1-4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


14 November-20 November 2001

During 5-11 November volcanic activity decreased at Karangetang in comparison to the previous week. No lava flows had been observed since 25 October. White plumes rose 100 m over the main crater and 50 m above Crater II. A "red reflection" was visible up to 20 m over the volcano. Multiphase earthquakes associated with lava dome growth were recorded. During 12-18 November visual observations revealed an increase in gas pressure, and plume emissions rising 600 m above the main crater. In addition, volcanic earthquakes increased in comparison to the previous week and no multiphase earthquakes were recorded. Karangetang remained at Alert Level 2 (on a scale of 1-4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


31 October-6 November 2001

On 29 October at 0029 an explosion from Crater IV, in the southern portion of the main crater, produced a gray cloud that rose 1.5 km above the crater. During 22-28 October white plumes rose 600 m above main crater, and 50-100 m above Crater II. A "red reflection" was observed reaching up to 75 m above the crater. The number of deep volcanic earthquakes increased compared to the previous week, but no seismicity associated with eruptive activity was recorded. Multiphase earthquakes, associated with lava dome growth, continued to be detected. The volcano remained at Alert Level 2 (on a scale of 1-4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


24 October-30 October 2001

During 15-21 October volcanic activity at Karangetang continued to decrease, as it did the previous week, and the Alert Level was reduced from 3 to 2 (on a scale of 1-4). The number of volcanic earthquakes decreased compared to the previous week and no avalanche, tremor, or explosion earthquakes were recorded. Multiphase earthquakes, associated with lava dome growth, were detected. White plumes rose 400 m above main crater, and 50-100 m above Crater II. A "red reflection" was observed reaching up to 25 m above the crater.

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


17 October-23 October 2001

During 8-14 October the number of deep volcanic earthquakes at Karangetang decreased compared to the previous week and no incandescent lava avalanches occurred. Steam plumes rose 400 m above the main crater and 50-100 m above Crater II. A 25-m-high "red reflection" was observed. The Alert Level remained at 3 (on a scale of 1-4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


3 October-9 October 2001

During 1-7 October there was an increase of deep volcanic earthquakes at Karangetang. On 1 and 2 October incandescent lava avalanches traveled from the main crater. Steam plumes rose 600 m above the main crater and 50-150 m above Crater II. A 50-m-high "red reflection" was observed. The Alert Level remained at 3 (on a scale of 1-4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


26 September-2 October 2001

During 17-23 September lava flows and lava avalanches rarely occurred at Karangetang. Small white-colored emissions rose ~500 m above the main crater and 50-200 m above Crater II. A 10- to 100-m-high "red reflection" was visible above the volcano. Seismic activity decreased in comparison to the previous week and was dominated by multiphase and avalanche earthquakes. During 24-30 September seismic activity continued to decrease and few lava avalanches were observed emanating from main crater. Plumes rose 400 m above the summit of the main crater and 50-100 m above Crater II. A 25-m-high "red reflection" was observed. The Alert Level remained at 3 (on a scale of 1-4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


19 September-25 September 2001

During 10-16 September fewer lava flows and lava avalanches traveled down the flanks of Karangetang than in the previous week. Lava flowed down the Kahetang and Keting rivers as far as 1.5 km, and one-km-long avalanches developed at the ends of these flows. Seismicity was dominated by small explosion and multiphase earthquakes. Emissions of steam and possibly ash at the northern main crater rose to 0.5 km. The volcano remained at Alert Level 3 (on a scale of 1-4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


12 September-18 September 2001

During 3-9 September lava flowed 0.5-1.8 km towards the Kahetang and Keting rivers. Lava avalanches that originated from the edges of the flows traveled up to 1 km. On 9 September at 0001 a pyroclastic flow traveled as far as 750 m from the main crater to the Batang River (West Siau). During the week seismicity was dominated by small explosion, avalanche, and multiphase earthquakes. Discontinuous volcanic tremor was also detected. The volcano remained at Alert Level 3 (on a scale of 1-4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


29 August-4 September 2001

During 13-26 August lava flowed ~1 km towards the Kehetang River, and ~1.6 km towards the Keting River. Avalanches that originated from the edges of the lava flows traveled up to 1.5 km. Seismicity was dominated by small explosion, avalanche, and multiphase earthquakes. The volcano remained at Alert Level 3 (on a scale of 1-4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


22 August-28 August 2001

During 30 July-12 August seismic activity at Karangetang was dominated by explosion, avalanche, and multiphase earthquakes. A steam-and-ash plume rose to 600 m above the volcano. During 1-12 August lava flows and lava avalanches were rarely observed. On 10 August cold lahars crossed roads as they traveled down the Batu Awang River and the Kahetang River. The volcano was at Alert Level 3 (on a scale of 1-4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


18 July-24 July 2001

During 9-15 July volcanic activity was at a level similar to the previous week. Seismicity was dominated by 572 small explosions, 451 multiphase earthquakes, and continuous lava avalanches. The avalanches traveled up to 2.5 km down the Keting River and lava flowed as far as 750 m down the Kahetang River. In addition, a gray plume was emitted from the volcano, which remained at Alert Level 3 (on a scale of 1-4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


11 July-17 July 2001

After eruptions occurred on 25 and 29 June, volcanic activity continued at high levels at Karangetang. During 30 June to 8 July seismographs recorded signals that represented small explosions, avalanches, and an average of 33 multiphase earthquakes per day. During this period a gray plume was emitted from the volcano, and lava avalanches traveled as far as 2.5 km down the Keting River and 750 m down the Kahetang River. The volcano is at Alert Level 3 (on a scale of 1-4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


2 May-8 May 2001

During 23-29 April Karangetang Observatory personnel observed lava flowing from Karangetang's main crater to a maximum distance of 700 m. A possible steam plume rose 500 m above the main crater. No seismic data were available. Karangetang remained at Alert Level 2 (on a scale of 1-4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


25 April-1 May 2001

During 16-23 April lava flowed from crater I to a maximum distance of 50 m, and lava avalanches often originated from the end of the lava flow and traveled about 750 m to the Nanitu River. In addition, a medium-gray plume that likely contained ash rose 50-300 m above the main crater, and a possible steam cloud from crater II rose 200 m above the summit. A red-colored reflection was visible rising 25 m above the volcano. Karangetang remained at Alert Level 2 (on a scale of 1-4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


11 April-17 April 2001

Observers noted that during 2-9 April a plume, which may have contained ash, rose 25-400 m above the volcano and a steam plume rose 200 m above crater II. A red-colored reflection was visible rising 25-75 m above the volcano. No seismic data were available. The volcano remained at Alert Level 2 (on a scale of 1-4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


7 February-13 February 2001

The VSI reported that since the 28 January eruption there has been no significant change in activity observed at Karangetang. Seismicity remained dominated by multi-phase earthquakes. The volcano remained at Alert Level 2 (on a scale of 1-4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


31 January-6 February 2001

The VSI reported that during 23-29 January explosive activity continued, with explosions on both 25 and 28 January. At 2227 on 25 January a minor explosion produced a thick ash plume that rose 700 m above the volcano, blew to the W, and dropped ash over the sea. The explosion also produced a lava avalanche that traveled ~1,250 m down the Kelitu River. The second explosion during the report period occurred at 2109 on 28 January and produced a Strombolian-type eruption with glowing ejecta that reached up to 300 m above the crater. In addition, a black ash-filled plume rose to ~1 km above the volcano. The explosion opened a new crater in the lava dome and produced a lava avalanche that traveled ~1.5 km down the W slope of the volcano. The volcano remained at Alert Level 2 (on a scale of 1-4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


17 January-23 January 2001

The VSI reported that at 0845 on 17 January a minor explosion produced ash and a lava avalanche. Ash fell around the villages of Salili and Beong and the lava avalanche traveled to the E and W. The volcano remained at Alert Level 2 (on a scale of 1-4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


10 January-16 January 2001

Explosions occurred at Karangetang on 2 and 7 January. At 1258 on 2 January an explosion sent an ash plume to ~500 m above the summit and at 1845 a glowing lava avalanche from the main crater flowed ~50 m to the Naitu River. A larger explosion on 7 January sent an ash plume to ~1,500 m above the summit and incandescent material reached a height of 200 m. Shocks from ash explosions were felt on the W side of the volcano in Pahe village, Lehi, Mini, and Kinali. "Glowing lava" flowed out to 1,000 m from the main crater down the Tanitu River. A minor explosion on 10 January produced ash that fell back into the crater. The volcano remained at Alert Level 2 (on a scale of 1-4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


20 December-26 December 2000

The VSI reported that during 12-18 December, activity increased at Karangetang in comparison to the previous week. A thin plume continued to be emitted from the main crater and Crater II, but it rose higher than last week: up to 150 m above the summit. A "red flame," possibly indicating illumination of the plume by lava fountaining or incandescent material at the summit, was observed rising up to 75 m above the summit. Overall seismic activity decreased in comparison to the previous week. The volcano remained at Alert Level 2 (ranging from 1 to 4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


13 December-19 December 2000

The VSI reported that during 5-11 December activity increased at Karangetang in comparison to previous weeks. Seismic activity was high, with an extreme increase in volcanic earthquakes. A thin plume was emitted from the main crater and Crater II; the plume rose up to 50 m above the summit and a "fire plume" reached up to 25 m above the summit. The volcano remained at Alert Level 2 (ranging from 1 to 4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


29 November-5 December 2000

The VSI reported that volcanic activity during 21-27 November was similar to the previous week. A thin ash plume was observed rising ~600 m above the summit from the main crater and Crater II. Booming sounds were frequently heard from the volcano's summit, and a "red flame" was observed some nights rising ~100 m above the summit. Seismic activity was high and dominated by discontinuous tremor. In total, 21 small explosions were recorded. The Alert Level remained at 2 (ranging from 1 to 4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


22 November-28 November 2000

The VSI reported that volcanic activity during 14-20 November was similar to the previous week. A thin ash plume was observed rising ~600 m above the summit from the main crater and crater II. A booming sound was frequently heard from the volcano's summit, and a "red flame" was observed some nights rising ~75 m above the summit. The Alert Level remained at 2 (ranging from 1 to 4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


15 November-21 November 2000

The VSI reported that volcanic activity continued at Karangetang. Low-level ash plumes were emitted from the main crater and crater II. A booming sound was frequently heard from the volcano's summit, and a "red flame" was observed some nights rising ~75 m above the summit. On 11 November a minor explosion produced a dark ash cloud that rose to 600 m above the summit, depositing material around the summit area. The Alert Level remained at 2 (ranging from 1 to 4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


8 November-14 November 2000

The VSI reported that volcanic activity continued at Karangetang. At 2030 on 2 November a small explosion produced an ash cloud that reached a height of 1.5 km above the volcano. The ejected material fell around the summit and flowed 1.5 km down the E, S, and W flanks of the volcano. A "red flame" was observed some nights rising ~ 75 m above the volcano's summit.

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


1 November-7 November 2000

VSI reported that at 1131 on 27 October a small explosion at Karangetang sent ash to 1 km above the volcano. The ash cloud drifted E over the sea and ash flowed ~1.5 down the E, W, and S flanks of the volcano. The volcano is at Alert Level 2 out of 4.

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)


Index of Bulletin Reports


Reports are organized chronologically and indexed below by Month/Year (Publication Volume:Number), and include a one-line summary. Click on the index link or scroll down to read the reports.

10/1968 (CSLP 33-68) Reported to be active

04/1974 (CSLP 54-74) Increased summit activity since January; frequent earthquakes

10/1976 (NSEB 01:13) New vent on the SW flank erupts lava and pyroclasts

11/1976 (NSEB 01:14) Additional details of September-October eruptive activity

01/1979 (SEAN 04:01) Occasional explosions since October

08/1979 (SEAN 04:08) Explosion from new flank vent

03/1980 (SEAN 05:03) Incandescent tephra from main crater

09/1980 (SEAN 05:09) Cauliflower-shaped cloud; incandescent tephra

08/1984 (SEAN 09:08) Tephra ejection, lava flows, lahars; 20,000 evacuated

09/1984 (SEAN 09:09) Seismicity and minor tephra emission since January; ash column and nuées ardentes in September

02/1985 (SEAN 10:02) Lava flow from S flank vent

11/1985 (SEAN 10:11) Small ash eruption

12/1985 (SEAN 10:12) Small gas plume in December

07/1987 (SEAN 12:07) Small explosions

09/1987 (SEAN 12:09) Rumblings, but no more explosions reported

07/1989 (SEAN 14:07) Flowing lava; white-gray plumes

08/1991 (BGVN 16:08) Explosive activity and glow

04/1992 (BGVN 17:04) Lava extrusion and incandescent tephra emission; pyroclastic flow kills six

06/1992 (BGVN 17:06) Some decline in explosive activity, lava production, and seismicity, but glowing rockfalls advance 1.5 km

11/1992 (BGVN 17:11) Heavy rains prompt lahar warning

12/1992 (BGVN 17:12) Ash ejection and hot lahars force evacuations

01/1993 (BGVN 18:01) Ash ejection and hot lahars force evacuations; no casualities

08/1994 (BGVN 19:08) Description of fumaroles and morphology

01/1996 (BGVN 21:01) Small ash plumes, incandescent ejecta, and increased seismicity

11/1996 (BGVN 21:11) October ash explosions and Strombolian eruptions

07/1997 (BGVN 22:07) Three people killed by a pyroclastic flow in June

07/1998 (BGVN 23:07) Incandescent material ejected in early July

05/1999 (BGVN 24:05) During March-May, weak ash emissions and rare incandescence

08/1999 (BGVN 24:08) Ash emissions and crater glow continue

11/2000 (BGVN 25:11) February-December included explosions, ash falls, lava flows, and debris flows

12/2000 (BGVN 25:12) Explosions generate ash plumes, ashfall, lava flows and avalanches

01/2001 (BGVN 26:01) Explosions in late January 2001 eject ash and lava

10/2001 (BGVN 26:10) April-October activity includes lava flows, lava avalanches, and ash plumes

01/2002 (BGVN 27:01) Lahars cause damage in January; explosions and lava flows in February

05/2002 (BGVN 27:05) Small explosions and increased seismicity during April 2002

08/2002 (BGVN 27:08) Shallow volcanic and small explosion earthquakes through early September

12/2002 (BGVN 27:12) 500-m plumes and ~ 1.5-km glowing lava avalanche; Alert Level increased

05/2003 (BGVN 28:05) Ash explosions from January through May 2003

07/2003 (BGVN 28:07) June 2003 ash plumes and two lava avalanches

09/2003 (BGVN 28:09) Ash explosions and lava avalanches in July; overall activity level declines

10/2003 (BGVN 28:10) White gas emissions and glow during October, but decreased seismicity

11/2003 (BGVN 28:11) Ash explosion on 28 October, then decreased seismicity

03/2004 (BGVN 29:03) Aviation report, stating ash to 7.5 km; seven MODIS alerts in ~ 1 year

05/2005 (BGVN 30:05) Ongoing seismicity during January-February 2005; lava avalanche in January

05/2007 (BGVN 32:05) Frequent activity since 2004, including lava emission and pyroclastic flows

08/2007 (BGVN 32:08) Eruptions during mid-2007; evacuations; pyroclastic flows; lava avalanches

01/2009 (BGVN 34:01) A 2007 plume rose to 12.2 km altitude; incandescent rockfalls

05/2009 (BGVN 34:05) Elevated seismicity, lava flows in May 2009; high alert, evacuations

01/2010 (BGVN 35:01) Lava flows and pyroclastic flows seen during 2009

02/2011 (BGVN 36:01) Eruption in August 2010 isolated 20,000 residents and caused four deaths

01/2014 (BGVN 39:01) 2011 into 2014: Spatter at crater, lava flows, and ash plumes




Bulletin Reports

All information contained in these reports is preliminary and subject to change.


10/1968 (CSLP 33-68) Reported to be active

Card 0114 (09 October 1968) Reported to be active

"The names of volcanoes in activity are Karangetang and Awu. Both are in Sangir Talaud Islands, North Sulawesi." [This report was received during the course of a Banua Wuhu eruption, and may simply be a listing other recently active volcanoes in the area.]

Information Contacts: Governor of North Sulawesi, Manado, Celebes, Indonesia.

04/1974 (CSLP 54-74) Increased summit activity since January; frequent earthquakes

Card 1840 (15 April 1974) Increased summit activity since January; frequent earthquakes

Api Siau recently showed increasing activity in the summit crater, which is filled with new lava. At night glowing lava could be observed, which sometimes flowed out over the crater rim. This phenomenon was preceded by felt earthquakes at the end of January 1974. Moreover, glares can be seen very often around the summit. On 10 February the glares were quite extensive, and rumblings could be heard. On 11 February at 1700 local time, a violent explosion took place, and red-hot lava fragments were thrown out to a distance of 1 km. After this explosion the activity consisted of the eruption of glowing lava fragments (Strombolian-type eruption) interchanged with the outflow of lava, which is limited to the summit part. On 23 February violent eruptions lasted throughout the night: glares around the summit, and the eruption of red-hot lava fragments which rolled down the slope, mainly in a southerly direction to the forest border. During the following days the activity ceased, but earthquakes could still be felt; strong quakes were recorded on 28 February at 0200 and 1600 local time. This caused the partial collapse of many houses and landslides in many areas.

A volcanological team made investigations at the scene on 7 March and reported the following: the lava dome had become higher and bigger; lava flowed down towards the Keting river (southern slope) 1 km distant, also in a westerly direction. Felt earthquakes continuously took place with time intervals of 5 minutes or less, but the number of quakes, as recorded by a "Spindler & Hoyer" mechanical seismograph, was decreasing when compared with previous days. On 13 March at 0825 local time another strong earthquake occurred. On 22 March, 23 earthquakes took place which caused a landslide at Mt. Tamata (another summit S of Api Siau). The next day six strong quakes caused the recording pen of the seismograph to jump, and rumblings on the summit were heard. The following day earthquakes took place every ten minutes. On 25 March at 1630 local time the most violent earthquake took place since the start of this eruptive activity, which again caused a landslide on Mt. Tamata and the complete collapse of a primary school in the capital city.

Information Contacts: Djajadi Hadikusumo, Geological Survey of Indonesia.

10/1976 (NSEB 01:13) New vent on the SW flank erupts lava and pyroclasts

An eruption of lava and pyroclastics from a new vent on the SW flank began on 15 September at about 0700, accompanied by loud rumbling. For 11 days before the eruption, ~120 earthquakes/day had been felt by inhabitants of the area. Continuous volcanic tremor was recorded at Tarorane Volcano Station from 15 September onwards. Through 5 October, an andesitic block lava flow, 20-40 m thick and 100-200 m wide, moved ~70 m/day, threatening the villages of Bubali and Salili, from which 1,800 people were evacuated. By 12 October, the flow rate had slowed to 20 m/day, but one edge of the flow was within 650 m of Ulu City, the capital of Siau Island. One spectator was killed and another badly injured on 19 September by a small avalanche, caused by the collapse of one flank of the flow as it reached the edge of a steep valley. The lava flow destroyed a bridge, 24 homes (44 others in the path of the flow were dismantled to avoid destruction), and killed an estimated 37,500 coconut, clove, and nutmeg trees. The flow is presently being mapped by a team of surveyors.

Information Contacts: D. Hadikusumo, VSI.

11/1976 (NSEB 01:14) Additional details of September-October eruptive activity

The following additional information is from a report by scientists from the Volcano Observation Section, Geological Survey of Indonesia.

The eruption was preceded by an earthquake swarm that began on 4 September. The number of felt earthquakes reached a maximum of 120/day early in the swarm, then gradually declined. At 0700 on 15 September, a minor pyroclastic eruption began from a new vent (A in figure 1) at about 1100 m elevation on the S flank, producing a thick ash cloud. This activity was succeeded by lava effusion from vent A. Another pyroclastic eruption occurred on 17 September from a second new vent (B in figure 1), about 300 m S of vent A. Lava effusion began shortly afterwards from B. The two flows coalesced near vent B and moved downslope 200-300 m/day. The rate of movement gradually decreased to 10 m/day as the flow front reached more level terrain. By 21 October, the flow was ~ 50 m thick near its source, ~6 km long, and was only 400 m from Ulu City, but lava extrusion had apparently ended. The flow front continued to advance 5-10 m/day. Thick "smoke" was still being emitted from the summit crater Karangetang. Lava volume was estimated at 2 x l07 m3.

Figure 1. Map of Api Siau, showing the 1974 and 1976 lava flows and the 1976 nuée ardente deposits. Courtesy of VSI.

Information Contacts: D. Hadikusumo, VSI.

01/1979 (SEAN 04:01) Occasional explosions since October

Three explosions from the summit crater occurred during October and two others were observed at night during November and early December. Ashfalls reached Ulu, 6 km SE of the summit (figure 1), where ~0.5 mm of ash was deposited.

A 10-minute eruption beginning at 1730 on 15 December produced a thick tephra column that rose 600-700 m above the summit and dropped more than 0.5 mm of ash on Ulu. Sharp explosion sounds were clearly audible from the temporary observatory at Tarorane, about 5 km from the summit. Volcanic tremors were frequently felt, but none were recorded at Tarorane.

Vapor emission from the 1976 vents has stopped, but a solfatara ~ 50 m above the upper vent emitted a thin stream of bluish gas.

Information Contacts: A. Sudradjat, M. Kamid, VSI.

08/1979 (SEAN 04:08) Explosion from new flank vent

On 31 May at about 0200 an explosion produced a new crater at about 1,300 m elevation on the NNW flank. A 600-m eruption column and a loud noise were reported. Gas emission from three vents in the new crater was continuing in mid-Aug and the 784 inhabitants of nearby villages remained on alert.

Information Contacts: A. Sudradjat, VSI.

03/1980 (SEAN 05:03) Incandescent tephra from main crater

Incandescent tephra was ejected to 200 m above the main crater on 24 March at 1905. As of 27 March, no additional activity had been observed.

Information Contacts: A. Sudradjat, VSI.

09/1980 (SEAN 05:09) Cauliflower-shaped cloud; incandescent tephra

A seismograph recorded an explosion . . . on 12 September at 0410. The next day at 1140, a cauliflower-shaped eruption column rose 1,200 m above the crater. Similar explosions had occurred on 3 July and three times in August, depositing incandescent tephra over an area 3 km in diameter.

Information Contacts: A. Sudradjat and L. Pardyanto, VSI.

08/1984 (SEAN 09:08) Tephra ejection, lava flows, lahars; 20,000 evacuated

Press sources reported that explosions 28 August and 5 September ejected dense ash clouds that rose to 4 km altitude. Ash and larger tephra fell over a wide area. Lava flows and lahars destroyed terraced rice fields and nutmeg orchards on the volcano's upper flanks. Magnitude 3-5 earthquakes had been felt since the beginning of September. About 25 shocks were felt near the volcano on 5 September, and some were also felt on nearby islands. By late 11 September, about half of Siau Island's 40,000 residents had been evacuated and officials warned people living on the lower flanks to be ready to leave quickly.

Information Contacts: UPI; DPA; AFP.

09/1984 (SEAN 09:09) Seismicity and minor tephra emission since January; ash column and nuées ardentes in September

An explosive eruption on 5 September was preceded by seismicity and nine months of minor tephra ejection. Rumblings were heard on 4 January, followed by an explosion that ejected ash. From February through April, rumbling preceded episodes of ash emission. On 31 May at 0724, an ash column rose to 1.5 km above the summit. During the night of 7-8 June, glowing lava fragments were ejected from the main crater. On 20 July, ash emission was accompanied by rumbling. The number of local seismic events increased through the first half of 1984 (table 1). Volcanic tremors were recorded 24 August, although no surface activity was seen. Ash emission occurred 3 September at 0447, producing an eruption column that rose 600 m. Glowing lava fragments were occasionally ejected. Rumbling accompanied the activity.

Table 1. Number of local earthquakes/month recorded at Karangetang. Courtesy of VSI.

    1984    Tectonic       Volcanic
           Earthquakes    Earthquakes

    Jan        62             18
    May        82             57
    Jun       200            139
    Jul       456             85

On 5 September at 0905, an ash column rose 4 km from the main crater. Nuées ardentes flowed 2 km S and 1 km W, with estimated volumes of 1.5 and 0.5 x 106 m3. One week later, ash emission was continuing and weak rumbling was heard. Ten volcanic and five tectonic earthquakes were recorded daily through 16 September. About 4,500 people were temporarily evacuated from the S and W sides of the danger zone but were allowed to work in their fields during the day. No casualties were reported.

Information Contacts: A. Sudradjat, VSI.

02/1985 (SEAN 10:02) Lava flow from S flank vent

A 4-day eruption began 24 February. Effusive material was erupted from a S flank new vent, about 300-400 m from the main crater. A lava flow extended ~350 m S (along the Batuawang River), stopping after four days. Inhabitants downslope of the lava flow were alerted, including the villages of Kola, Bola, and Kopi. Harmonic tremor indicated lava movement a few hours before effusive activity began, but no other significant changes in seismicity were detected during the activity.

Api Siau has been the site of nearly continuous activity for the last 20 years.

Information Contacts: A. Sudradjat, VSI.

11/1985 (SEAN 10:11) Small ash eruption

"Api Siau erupted from the main crater (Kawah Utama) on 6 November. A 1.5-km-high ash column covered villages S of the volcano (Salili, Beong, Kanawong, and Lehi) with 1-3 mm of ash. Detonations were heard from the observation post at Muaralawa, 4.5 km SW of the volcano. Additional detonations were reported throughout the month. Possible precursory signs of this activity included a darkening of the normally whitish quiescent plume beginning on 4 November."

Information Contacts: T. Casadevall and L. Pardyanto, VSI.

12/1985 (SEAN 10:12) Small gas plume in December

Api Siau was quiet during December with only a small gas plume continuing to be emitted.

Information Contacts: Suparto S. and T. Casadevall, VSI.

07/1987 (SEAN 12:07) Small explosions

Three small explosions occurred during July, but no details were available.

Information Contacts: VSI.

09/1987 (SEAN 12:09) Rumblings, but no more explosions reported

Rumblings from the volcano were heard during September. . . . no activity had been reported in August.

Information Contacts: VSI.

07/1989 (SEAN 14:07) Flowing lava; white-gray plumes

White to sometimes gray emissions under low-medium pressure rose to 250 m above the crater, often accompanied by glowing lava that was clearly seen at night. Earthquakes of MM I-II were felt on 14 July at 2240, 22 July at 1323 and 26 July at 1915. The type and number of earthquakes recorded were: 45 distant tectonic, 20 local tectonic, and one degassing. The volcano's level of activity appeared to be decreasing and was lower than normal in late July.

Information Contacts: VSI.

08/1991 (BGVN 16:08) Explosive activity and glow

Explosions were clearly visible from the coast (at Ulu Siau) during a visit 2-4 July. A diffuse, red, summit-area glow was continuously observed. Some small earthquakes were felt.

Information Contacts: V. Clavel and P. Vetsch, SVG, Switzerland.

04/1992 (BGVN 17:04) Lava extrusion and incandescent tephra emission; pyroclastic flow kills six

A pyroclastic flow, triggered by collapse of a lava flow front, killed six people on 11 May.

After an increase in seismicity to as many as 4 events/week in April-May 1991, ash explosions began in the main central crater, ejecting incandescent projectiles to 50-75 m height (16:08). Strombolian activity lasted until August, when lava emission began in the main crater. During September, explosive activity decreased to ash emissions 25-75 m high, accompanied by audible explosions and some incandescence.

Activity increased in February 1992, and incandescent ash emissions became continuous. An estimated 6 x 106 m3 of lava had accumulated in the crater and lava flows began to advance down the S flank's Kali Keting valley. On 2 March, VSI and local authorities warned farmers along the upper Kali Keting to be prepared for the possibility of collapse of the lava flow front and subsequent generation of pyroclastic flows. This region was designated on the 1989 VSI volcano hazard map as being at highest risk of destruction (by pyroclastic flows). At 1330 on 11 May, a pyroclastic flow caused by the collapse of the lava flow front traveled 4 km from the main crater down the Kali Keting, burning seven farmers (six of whom later died in hospitals) and destroying >30 houses and ~2 km2 of coconut, cassava, and nutmeg farms. The pyroclastic-flow deposit had a volume of ~1.2 x 106 m3 (roughly 20% of the lava in the crater). The eruption was continuing as of 19 May, as indicated by the increasing number of volcanic earthquakes and seismically recorded degassing events (table 2).

Table 2. Monthly seismicity at Karangetang, February-19 May 1992. Courtesy of VSI.

    Date     Volcanic      Degassing    Tectonic        Felt
             earthquakes     Events     Earthquakes     Shocks
           A-type  B-type             Local  Distant

    Feb      --      --        12      221     289        4
    Mar      --      --       345      101     252        1
    Apr      --      --       253      150     158        2
    May      21      23       500       13      41        1
     (1-19)

Information Contacts: W. Modjo, VSI; UPI.

06/1992 (BGVN 17:06) Some decline in explosive activity, lava production, and seismicity, but glowing rockfalls advance 1.5 km

Activity began to increase in February 1992. Glowing rockfalls on 18 May filled the upper Keting river valley to 4 km from the crater. The volume of the deposit was estimated at 1.2 x 106 m3, ~ 20% of the dome (17:04). Since then, the eruption has fluctuated, but a general decrease in intensity was indicated by declines in the height of the ash plume, the behavior of the glowing lava flow, and the vigor of incandescent tephra ejection. In July, glowing rockfalls advanced down the Keting river to 1,500 m from the crater. The number of volcanic and local tectonic earthquakes decreased in June and July compared to previous months. June-July seismicity was dominated by surface activity, such as explosion earthquakes and rockfalls (figure 2).

Figure 2. Tectonic seismicity (top) and volcanic earthquakes (bottom) at Karangetang, June-July 1992. Courtesy of VSI.

Information Contacts: W. Modjo, VSI.

11/1992 (BGVN 17:11) Heavy rains prompt lahar warning

Heavy rainfall has recently occurred on the S flank, where six farmers were killed by a pyroclastic flow in May (17:04). Local authorities were officially warned of the lahar hazard to farmers in the area. Activity at the volcano has declined to normal levels since August.

Information Contacts: W. Modjo, VSI.

12/1992 (BGVN 17:12) Ash ejection and hot lahars force evacuations

Activity began on 21 January [1993], when a hot mudflow was observed at 1714 flowing S along the Bahembang River to 4.5 km from the summit. The eruption of hot mud and ash forced the evacuation of 452 people. No casualties had been reported by 25 January, but a bridge linking the villages of Dame and Karanglung, ~4 km SSW, was destroyed by hot ashes. Ashfall was also reported 3-6 km SE and SSE of the summit (in the villages of Bubali, Salili, Panili, and Ondang). Official lahar warnings were issued in November after heavy rainfall on the S flank of the volcano . . . .

Information Contacts: ANS.

01/1993 (BGVN 18:01) Ash ejection and hot lahars force evacuations; no casualities

This report provides additional information about the 21 January eruption described in 17:12. Activity increased at 2335, with ejection of incandescent lava fragments and gray ash clouds. The 21 January explosion was followed by rumbling sounds and ejection of lava fragments that avalanched 750 m down the Beha valley. The press reported that a hot mudflow was observed at 1714 flowing S along the Bahebang River to 4.5 km from the summit, forcing the evacuation of 452 people. No casualties were reported, but avalanches or nuées ardentes damaged two houses near the outlet of the Bahebang river on 21 January, and another five are threatened by rain-induced lahars. The press noted that a bridge linking the villages of Dame and Karanglung, ~ 4 km SSW, was destroyed by hot ashes, and ashfall was reported 3-6 km SE and SSE of the summit (in the villages of Bubali, Salili, Panili, and Ondang). Avalanches and rumbling noises were continuing as of 10 February.

Information Contacts: W. Tjetjep, VSI; ANS.

08/1994 (BGVN 19:08) Description of fumaroles and morphology

"During observations at 1145 on 15 July from the SW flank, a white plume rose above the volcano and extended toward the E. Two active lava domes were present on the summit, one in the S, and the other in the NE. Each generated white plumes from its top. Many fumaroles with yellow sulfur deposits covered the S side of the NE dome. A small chaotic-looking lava flow was located near the foot of the NE lava dome. It was possible to hear weak, rhythmic explosions from an area located between the two lava domes behind the summit pass, but no direct observations were possible because of the cover of rising clouds."

Information Contacts: H. Gaudru, C. Pittet, M. Auber, C. Bopp, and O. Saudan, EVS, Switzerland.

01/1996 (BGVN 21:01) Small ash plumes, incandescent ejecta, and increased seismicity

On 9 and 16 November "thunderclaps" were heard from the summit. A gray plume 500 m high was observed, and incandescent ejecta rose 10-50 m above the summit at night. On 17 December thunderclaps were heard again and ejecta rose 100 m above the summit. Seismicity increased from 26 October until the end of 1995. Daily counts of deep volcanic (A-type) earthquakes fluctuated up to 116 (figure 3).

Figure 3. A-type seismicity at Karangetang, September-December 1995. Courtesy of VSI.

Information Contacts: Wimpy S. Tjetjep (Director), Volcanological Survey of Indonesia (VSI), Jalan Diponegoro 57, Bandung, Indonesia.

11/1996 (BGVN 21:11) October ash explosions and Strombolian eruptions

During October, Karengetang produced ash explosions and occasional Strombolian eruptions every day. These rose to several hundred meters above the crater rim. The eruptions resulted in pyroclastic materials accumulating on the summit, a situation that could lead to hazardous lahars in the rainy season.

Information Contacts: Wimpy S. Tjetjep, Volcanological Survey of Indonesia, Jalan Diponegoro No. 57, Bandung 40122, Indonesia (Email: vsimvo@ibm.net).

07/1997 (BGVN 22:07) Three people killed by a pyroclastic flow in June

On 17 April the Bureau of Meteorology in Darwin received a report from the Volcanological Survey of Indonesia of an ongoing eruption at Karangetang; however, the plume height could not be observed because of cloud cover, and no plume was seen in later satellite imagery. The Societe de Volcanologie de Geneve (SVG) reported that explosions and pyroclastic flows in June required the evacuation of 400 people from a village. They further reported that this eruptive episode claimed the lives of three people. The last reported activity consisted of daily ash explosions during October 1996.

Information Contacts: Bureau of Meteorology, Northern Territory Regional Office, P.O. Box 735, Darwin NT, Australia; Societe de Volcanologie Geneve (SVG), B.P. 298, CH-1225, Chenebourg, Switzerland.

07/1998 (BGVN 23:07) Incandescent material ejected in early July

During early July observers noted incandescent materials at night. They also saw a plume emitted from the main crater rising to 25-50 m in height. Around this time, seismic events occurred less often compared to previous weeks.

Information Contacts: Volcanological Survey of Indonesia, Jalan Diponegoro No.57, Bandung 40122, Indonesia (URL: http://www.vsi.esdm.go.id/).

05/1999 (BGVN 24:05) During March-May, weak ash emissions and rare incandescence

Between 9 March and 24 May, a "thick white ash plume" was emitted from the main crater and rose to 300-500 m, while a "thin white ash plume" rose to ~150 m from Crater II. Occasionally incandescence was seen in the column rising from the main crater to heights of 25 m. Some A-type earthquakes occurred throughout the reporting period, but seismicity was dominated by tectonic events that frequently exceeded 200/week.

Karangetang (Api Siau) lies at the northern end of the island of Siau, N of Sulawesi, and contains five summit craters strung along a N-S line. One of Indonesia's most active volcanoes, Karangetang has had more than 40 recorded eruptions since 1675. Twentieth century eruptions have included frequent explosions, sometimes accompanied by pyroclastic flows and lahars.

Information Contacts: Volcanological Survey of Indonesia (VSI), Jalan Diponegoro No. 57, Bandung 40122, Indonesia (URL: http://www.vsi.esdm.go.id/).

08/1999 (BGVN 24:08) Ash emissions and crater glow continue

Ash emission and crater glow continued at Karangetang during the last week of May. Main Crater produced a column of thick white ash that rose 450 m above the summit. Glow was seen up to 75 m above the crater. Crater II produced a dull white column of ash 150 m in height. Tectonic events dominated the seismic record (figure 4).

Figure 4. The number of volcanic and tectonic earthquakes recorded at Karangetang during June-September 1999. Data courtesy of VSI.

This pattern of activity continued with minor changes in the height or density of ash columns at both craters and the intensity or height of glow seen at Main Crater until late in June. During early July, thick fog sometimes prevented observation of the summit. The pattern of thick ash columns rising a few hundred meters above the summit accompanied by glow up to 50 m above the summit resumed in mid-July and continued with a tendency to decreasing intensity until late September.

Information Contacts: Volcanological Survey of Indonesia (VSI), Jalan Diponegoro No. 57, Bandung 40122, Indonesia (URL: http://www.vsi.esdm.go.id/).

11/2000 (BGVN 25:11) February-December included explosions, ash falls, lava flows, and debris flows

The following report covers activity during February to mid-December 2000. At the beginning of February, the main crater of Karangetang (also known as Api Siau) produced a light-colored ash emission that rose 250-350 m, while Crater II emitted a lighter ash plume to a height of 75-100 m. At night the ash column glowed red to a height of 10-25 m. Similar activity continued through May; variable-density emissions from the main crater rose to a maximum height of 500 m, those from Crater II rose up to 150 m, red illumination was visible up to 75 m at night, and rumbling was heard intermittently through May.

In mid-June tremor events with amplitudes of 0.5-10.5 mm dominated seismicity. Ash plumes continued to rise from both craters, and lava fountaining was observed at the main crater. A lava flow and a debris avalanche sent material up to 300 m from the summit down to the Bahembang River. Red summit illumination was visible at night. Another lava flow and debris avalanche occurred in late June, lava fountains reached 50 m above the summit at times, and the maximum amplitude for tremor was 33 mm in early September. Relatively similar activity persisted through the end of the month.

During mid-October, activity increased significantly. The two craters continued to emit light-colored, variable-density ash plumes, and thundering could be heard. At 1840 on 14 October, observers saw lava flowing 100 m down to the Nenitu River. Lava avalanches traveled up to 1,000 m from the summit. Seismicity increased notably with many A-type earthquakes, tectonic earthquakes, explosive events, and continuous tremor. At 1131 on 27 October, a small explosion sent a dark ash plume to a height of 1 km. An ash cloud drifted E to the sea, while pyroclastic flows burned vegetation along their paths and reached ~1,500 m down the E, W, and S flanks. During this period, multi-phase earthquakes occurred and tremor became discontinuous.

Another explosion at 2030 on 2 November sent dark ash 1.5 km above the summit. Ashfall and pyroclastic flows occurred along the flanks; ash followed a similar pattern of distribution as after the 27 October explosion. Seismicity quieted slightly following this explosion. A smaller explosion occurred on 11 November and dark ash rose 600 m. Ash fell around the summit area, and no injuries were reported. Red illumination at night and frequent booming sounds accompanied ash plumes that continued to rise from the main crater and Crater II during October-November.

Seismicity increased by 12 December with nearly fifteen times as many multi-phase earthquakes as in late November, and the resumption of continuous tremor. Thundering sounds continued to be heard often, and red summit illumination could be observed occasionally at night. The main crater and Crater II emitted a light-colored, variable-density ash plume to 150 m above Karangetang's summit. The volcano maintained a hazard status of 2 (on a 1-4 scale) during the report period.

Information Contacts: Dali Ahmad, Volcanological Survey of Indonesia (VSI), Jalan Diponegoro No. 57, Bandung 40122, Indonesia (Email: dali@vsi.esdm.go.id, URL: http://www.vsi.esdm.go.id/).

12/2000 (BGVN 25:12) Explosions generate ash plumes, ashfall, lava flows and avalanches

Heightened activity continued at Karangetang in late December 2000-late January 2001, following a year of frequent activity in 2000 (BGVN 25:11). The main crater and Crater II sent a white, variably-thick ash plume up to 600 m above the summit during 19-25 December. Plume illumination up to 150 m above the craters was visible at night. Lava flows occurred on 21-22 December and reached as far as 1,250 m laterally along the SW flank. The seismic record also showed increased activity with multi-phase earthquakes predominating.

Activity, however, tailed off during 26 December-1 January before increasing again with renewed vigor from 2 to 8 January. At 1258 on 2 January an explosion produced a white-gray ash plume that rose ~500 m above the summit. At 1845 on the same day, workers observed a glowing lava avalanche issuing from the main crater and moving 50 m from the summit down toward the Naitu River. A larger explosion on 7 January sent gray ash 1,500 m above Karangetang. A coeval Strombolian eruption cloud rose 200 m. Ashfall occurred W of the volcano, coating Pahe, Lehi, Mini, and Kinali villages. Lava flowed down to the Tanitu River as far a 1 km from the summit. Tectonic earthquakes dominated seismicity during the week, and a significant number of tremor earthquakes also occurred.

A minor explosion occurred on 10 January; ash rose and subsequently fell back into the crater. Tectonic earthquakes again overshadowed all other types during 9-15 January. At 0845 on 17 January an explosion generated a small ash plume and a lava avalanche. Ash fell on Salili and Beong villages; lava flowed down both the E and W flanks of the volcano. Seismicity remained elevated with earthquake distributions similar to the previous week. The VSI maintained a hazard status of 2 (on a scale of 1-4) for Karangetang throughout the report period.

Information Contacts: Dali Ahmad, Volcanological Survey of Indonesia (VSI), Jalan Diponegoro No. 57, Bandung 40122, Indonesia (Email: dali@vsi.esdm.go.id, URL: http://www.vsi.esdm.go.id/).

01/2001 (BGVN 26:01) Explosions in late January 2001 eject ash and lava

Eruptive activity at Karangetang since the previous report (BGVN 25:12) continued through 5 February 2001. A minor explosion occurred at 2227 on 25 January and produced an ash-heavy plume that rose 700 m; ash fell into the sea W of the volcano. The eruption also featured a molten lava avalanche that flowed down to the Kelitu River with a maximum runout distance of ~1,250 m from the summit. At 2109 on 28 January a second, Strombolian-style explosion occurred that sent glowing ejecta 300 m above the crater; a black ash cloud rose 1 km and ashfall was observed on a nearby beach. The 28 January eruption also sent lava avalanches ~1,500 m down Karangetang's W flank. Seismicity for the period 23-29 January was dominated by multi-phase earthquakes.

During 30 January-5 February no significant visual activity was observed; multi-phase earthquakes outnumbered all others during the week. VSI maintained a hazard status of 2 (on a scale of 1-4) for Karangetang, and no further eruptive episodes were reported.

Information Contacts: Dali Ahmad, Volcanological Survey of Indonesia (VSI), Jalan Diponegoro No. 57, Bandung 40122, Indonesia (Email: dali@vsi.esdm.go.id, URL: http://www.vsi.esdm.go.id/).

10/2001 (BGVN 26:10) April-October activity includes lava flows, lava avalanches, and ash plumes

The frequent, but spasmodic, activity witnessed during 2000 and the early part of 2001 at Karangetang quieted somewhat between mid-February and mid-April, although the Alert Level remained at 2 (on a scale of 1-4). During late April and early May, the Volcanological Survey of Indonesia (VSI) reported lava flowing from the crater. Lava avalanches that originated at the end of the lava flow traveled 750 m to the Nanitu River. A likely ash plume rose 50-300 m above the main crater and a steam cloud from Crater II rose 200 m above the summit. Plume illumination was visible 25-75 m above the volcano.

Volcanic activity continued at high levels after eruptions on 25 and 29 June. During early July, seismographs registered small explosions, avalanches, and an average of 33 earthquakes/day. A gray plume was emitted. As a result of this increased activity, the Alert Level was raised to 3. During the remainder of July and August, explosions, avalanches, and earthquakes continued to dominate seismicity. During 9-15 July, there were 572 explosions, 451 earthquakes, and continuous lava avalanches; one avalanche traveled 2.5 km down the Keting River and lava flowed 750 m down the Kahetang River. On 10 August, cold lahars crossed roads as they traveled down the Batu Awang and the Kahetang Rivers.

Similar seismic activity, lava flows, and lava avalanches continued into mid-September. On 9 September, a pyroclastic flow traveled as far as 750 m from the main crater to the Batang River (West Siau). During 10-16 September, the number of lava flows and avalanches decreased. Lava flowed 1.5 km down the Kahetang and Keting rivers, and avalanches extended 1 km. Small explosions and earthquakes continued, while emissions of steam and possibly ash at the N main crater rose to 0.5 km above the summit. During the rest of September, seismicity decreased, and lava flows and avalanches were rare.

Deep volcanic earthquakes increased during early October, and during 1-2 October incandescent lava avalanches traveled from the main crater and steam plumes rose 600 m above the main crater and 50-150 m above Crater II. Plume illumination was observed to 50 m above the volcano. The Alert Level was reduced to 2 because of the decrease in deep earthquake activity that occurred the following week.

During 22-28 October, the number of deep volcanic earthquakes increased but no seismicity associated with eruptive activity was recorded. White plumes continued to rise above the main crater and Crater II, plume illumination was observed above the crater, and multi-phase earthquakes, associated with lava-dome growth, were detected. On 29 October a minor explosion from Crater IV produced a gray cloud that rose 1.5 km above the crater. As of the end of October, the Alert Level remained at 2.

Information Contacts: Dali Ahmad, Volcanological Survey of Indonesia (VSI), Jalan Diponegoro No. 57, Bandung 40122, Indonesia (Email: dali@vsi.esdm.go.id, URL: http://www.vsi.esdm.go.id/).

01/2002 (BGVN 27:01) Lahars cause damage in January; explosions and lava flows in February

During 5 November 2001 through 24 February 2002, seismicity continued at Karangetang, and plumes were observed rising above the summit (table 3). The lava flows that began during late April and early May 2001 (see BGVN 26:10) stopped around 25 October. Multiphase earthquakes, associated with lava dome growth, had not been registered since September but began again during early November.

Table 3. Seismicity and plumes observed at Karangetang during 5 November through 24 February. The Alert Level remained at 2 throughout this period. Courtesy VSI.

    Date (2001-02)   Deep volcanic   Shallow volcanic   Tectonic   Multiphase
                       (A-type)         (B-type)
        Observation (plume heights are above summit)

    05 Nov-11 Nov          7              --               51           11
        White medium-thick plume rose 100 m above N crater, 50 m above crater
        II; incandescence to 20 m

    12 Nov-18 Nov         14               4               49           --
        White medium-thick plume rose 600 m; incandescence to 25-50 m

    19 Nov-25 Nov         12               9               36

    26 Nov-02 Dec         14               2               66            5
        White medium-thick plume rose 300 m above main crater, 150 m above
        crater II

    03 Dec-09 Dec         13               9               45           11
        White thin-medium plume rose 50-250 m above main crater, 100 m above
        crater II

    17 Dec-30 Dec         17              16               60           12
        White medium-thick plume rose 500 m above main (S) crater, 50 m above
        crater II

    30 Dec-06 Jan         10               5                9            7
        Lahars on 3 January

    07 Jan-13 Jan         18               8               56            9
        White medium-thick plume rose 400 m above summit, incandescence inside
        the plume to 50 m

    14 Jan-20 Jan          4               7               44            1

    21 Jan-27 Jan          4               6               29            6

    28 Jan-03 Feb          8               1               36           12
        White medium-thick plume rose 100 m above main (S) crater, 75 m above
        N crater; incandescence to 25 m

    04 Feb-10 Feb        407             215              967           23
        Incandescence to 25 m

    11 Feb-17 Feb        281              73              102            3
        Ash to WSW, lava flows, incandescence to 25 m

    18 Feb-24 Feb        113              16              100            1
        Incandescence to 25 m

During the first days of 2002 heavy rains near the summit resulted in cold lahars along the Kahetang river on the E flank. On 3 January around 1200 a lahar traveled ~260 m and was ~10-125 cm thick near Terminal and Pelabuhan Ulu Siau. The volume of the lahar was estimated to reach 40,000 m3. In this area, a total of 52 houses were destroyed. Near Bebali village, a lahar traveled ~60 m and covered the road along Ulu Siau city to Ondong village to a thickness of ~75 cm. The volume of the lahar was estimated at 600 m3. In this area, 9 houses and a church were damaged.

Seismicity increased during early February, and a thundering sound was heard frequently coming from the main (S) crater, often accompanied by a sulfur smell. During a 3-day period in early February, 82 earthquakes occurred with magnitudes of 1-3. The earthquakes often caused sliding of the unstable 2001 lava. On 11 February, an explosion occurred that produced ash falls 0.5-1 mm thick to the WSW, reaching the Kanawong, Lehi, Mimi, Kinali, and Pehe villages. Incandescent lava flows traveled up to 1.5 km down the Beha river (W slope) and Kahetang river (E slope). Seismicity was still high but decreased after the 11 February explosion. Loud noises, sulfur smells, and incandescence were observed through at least 24 February.

Information Contacts: Dali Ahmad, Volcanological Survey of Indonesia (VSI), Jalan Diponegoro No. 57, Bandung 40122, Indonesia (Email: dali@vsi.esdm.go.id, URL: http://www.vsi.esdm.go.id/).

05/2002 (BGVN 27:05) Small explosions and increased seismicity during April 2002

During 25 February through at least 16 June 2002, seismicity at Karangetang was dominated by shallow volcanic (B-type) and tectonic earthquakes (table 4). Thick, white, medium-pressure plumes were typically emitted from the main crater (S) and reached 50-500 m above the crater rim. During late May through at least 16 June, a thin-medium white plume was emitted from crater II (N) and reached 150-200 m above the crater rim. During most of the report period a red reflection was observed around the summit at night, rising 10-75 m.

Table 4. Earthquakes recorded at Karangetang during 25 February through 16 June 2002. The Alert Level remained at 2 throughout this period. Courtesy VSI.

    Date (2002)     Deep volcanic   Shallow volcanic   Multiphase   Tectonic
                      (A-type)         (B-type)

    25 Feb-02 Mar        52                5               6           62
    03 Mar-10 Mar        44               20               2          201
    11 Mar-17 Mar        29                8               9          100
    18 Mar-24 Mar        15                8               6           83
    25 Mar-31 Mar        20                9               2          112
    01 Apr-07 Apr        27                3               2           71
    08 Apr-14 Apr        17               64              --           82
    15 Apr-21 Apr        26               74              --          147
    22 Apr-28 Apr        17               61               2          146
    29 Apr-05 May        28               99               6          139
    06 May-12 May        22               70               0          132
    13 May-19 May         8               77               1          112
    20 May-26 May        22               93               6          146
    27 May-02 Jun        18             1228               4          113
    03 Jun-09 Jun        13              119               3           75
    10 Jun-16 Jun        12               62               1           45

Several eruptions occurred during the report period. An eruption on 5 March at 1344 emitted ash that reached 1.5 km above the summit. Ash fell on the NE flank and a lava avalanche also occurred. During the week of 3-10 March, 1 earthquake was felt. On 23 March 2002 at 1115 a thundering sound was heard from main crater, followed by a lava avalanche that flowed down to Kahetang and Batu Awang rivers. A thundering sound was heard beginning at 1615 on 28 March until 2007 on 29 March. No lava avalanches occurred during this time, but 3 earthquakes were felt during the last week of March. A medium explosion on 7 April at 2115 emitted thick gray ash to ~400 m above the crater rim.

The number of deep and shallow volcanic earthquakes increased during April (table 4). An ash explosion on 12 May at 1116 emitted ash that reached 750 m above the crater before falling to the sea on the E side. The explosion was followed by a lava avalanche that flowed ~500 m down the Batu Awang and Kahetang rivers. An explosion on 26 May at 1747 emitted white-gray ash that reached 300 m above the crater rim before falling to the sea on the W side. During 3-9 and 10-16 June, 2 and 5 small explosions occurred per week, respectively. Karangetang remained at Alert Level 2 throughout the report period.

Information Contacts: Dali Ahmad, Volcanological Survey of Indonesia (VSI), Jalan Diponegoro No. 57, Bandung 40122, Indonesia (Email: dali@vsi.esdm.go.id, URL: http://www.vsi.esdm.go.id/).

08/2002 (BGVN 27:08) Shallow volcanic and small explosion earthquakes through early September

During 17 June-8 September 2002, seismicity at Karangetang was dominated by shallow volcanic (B-type) and small explosion earthquakes (table 5). The volcano's two currently active craters, the main crater and crater II lie to the S and N, respectively. The main crater nearly always issued white, medium-thick ash plumes that reached up to 500 m above the rim. The Alert Level remained at 2 throughout the report period.

Table 5. Earthquakes recorded at Karangetang during 17 June through 8 September 2002. "Plume details" compile visual observations from an observatory post at Salili, a village on the upper S flank. The plume from the main crater was nearly always described as "white, medium-thick" unless noted otherwise (as on 7-8 September). The plume from crater II was typically described as a "white ash plume" (exceptions noted). As noted in the text, the Alert Level remained at 2 throughout this period. Courtesy VSI.

    Date (2002)    Deep      Shallow    Multiphase    Small       Tectonic
                   volcanic  volcanic                 explosion/
                   (A-type)  (B-type)                 emission
       Plume Details (heights are above the summit)

    17 Jun-23 Jun    25        121           5           14          73
       Plume emitted from main crater reached 350 m; plume from crater II
         rose 50 m; red reflection reached 25 m.
    24 Jun-30 Jun    17        166           0           10          97
       Plume emitted from main crater reached 200 m; plume from crater II
         rose 50 m; red reflection reached 25 m.
    01 Jul-07 Jul     8        106           1            3          80
         Ash plume from main crater reached 100 m, light plume also observed,
           but not clearly. Ash plume from crater II rose 25 m.
    08 Jul-14 Jul    64        144           0            4          78
         Medium-thick ash plume from main crater reached 100 m; light plume
           also observed reaching 10 m. Thin ash plume from crater II rose
           50 m. One explosion event.
    15 Jul-21 Jul     8         45           5           24          77
         Medium-thick ash plume from main crater reached 500 m; light plume
           also observed reaching 10 m. Thin ash plume from crater II rose
           250 m. One explosion event.
    22 Jul-28 Jul    75        122           4           20          89
         Ash plume from main crater reached 350 m; light plume also observed
           reaching 10 m. Thin ash plume from crater II rose 250 m. Two
           explosion events.
    29 Jul-04 Aug     4         31           2           13          77
         Ash plume from main crater reached 400 m; light plume also observed
           reaching 25 m. Thin ash plume from crater II rose 200 m.
    05 Aug-11 Aug    11         54           0            9          95
         Ash plume from main crater reached 400 m; light plume also observed
           reaching 25 m. Thin ash plume from crater II rose 200 m.
    12 Aug-18 Aug    12         27          22           46          77
         Ash plume from main crater reached 150 m; light plume also observed
           reaching 25 m. Thin ash plume from crater II rose 50 m.
    19 Aug-25 Aug    64        106         129          216          36
         Ash plume from main crater reached 150 m; light plume also observed
           reaching 25 m. Thin ash plume from crater II rose 50 m.
    26 Aug-01 Sep    28         70         128          436          31
         Ash plume from main crater reached 150-200 m; thin-medium ash plume
           from crater II rose 25 m.
    02 Sep-08 Sep     7         28           2          586    30
         Ash plume from main crater reached 300-400 m; thundering sounds
           during 7-8 September were accompanied by a gray ash plume from main
           crater. Thin ash plume from crater II rose 25 m.

The Volcanological Survey of Indonesia (VSI) reported several explosions. On 8 July at 1806 a loud explosion from the main crater produced a white-gray ash plume that rose 1.0 km. Ash from the explosion spread NNW, while incandescence on the W flank burned vegetation. On 15 July at 1355 another loud explosion from the main crater produced white-gray ash that rose 1.5 km and spread N. A lava avalanche that accompanied the explosion entered the valley of the Kahetang river as far as 1.5 km. Multiphase earthquakes were recorded 5 times on 20 July. On 26 July at 0042 a very loud explosion heralded a lava avalanche to the W and partly to the E. The next day, at 1403, another explosion produced a lava avalanche in the same direction. The height of the ash from the explosion could not be determined because thick fog covered the edifice. Several felt tectonic earthquakes took place on 24 July, at 1014, 1839, and 1840 (intensity III on the modified Mercalli scale). Afterwards, there was a significant increase in seismic activity, mostly in deep- and shallow-volcanic earthquakes. Deep volcanic earthquakes increased from two on 23 July prior to the felt earthquakes to 58 on 24 July, while shallow volcanic earthquakes increased from 8 to 69. On 26 and 27 July, two avalanche earthquakes were recorded.

Information Contacts: Volcanological Survey of Indonesia (VSI), Jalan Diponegoro No. 57, Bandung 40122, Indonesia (Email: dali@vsi.esdm.go.id, URL: http://www.vsi.esdm.go.id/).

12/2002 (BGVN 27:12) 500-m plumes and ~ 1.5-km glowing lava avalanche; Alert Level increased

During September-29 December 2002, seismicity at Karangetang was dominated by emission, multiphase and tectonic earthquakes (table 6). The S crater nearly always issued "white, thin ash plumes" that reached up to 500 m above the rim. At night, a light plume was visible rising 25-100 m. Loud noises were heard frequently, and the N crater emitted a "thin white ash plume" to 50 m. No ashfall was reported.

Table 6. Earthquakes recorded at Karangetang during 9 September-29 December 2002. No reports were issued for Karangetang during 25 November-22 December. Courtesy VSI.

    Date (2002)       A-type      B-type     Explosion    Multiphase
	           volcanic    volcanic

    09 Sep-15 Sep       14          24           0            94
    16 Sep-22 Sep       28          27           0            82
    23 Sep-29 Sep       22          26           1            20
    30 Sep-06 Oct       14           4           0            38
    07 Oct-13 Oct       19          13          --            30
    14 Oct-20 Oct        7          22           1            30
    21 Oct-27 Oct       12          34          --            23
    28 Oct-03 Nov       18         154          --           147
    04 Nov-10 Nov       15          29          --            90
    11 Nov-18 Nov       12          40           1            75
    19 Nov-24 Nov       15         116          --            94
    23 Dec-29 Dec       10          26           1           168

    Date (2002)      Emission    Tectonic    Avalanche

    09 Sep-15 Sep      299          46           --
    16 Sep-22 Sep      246          39           --
    23 Sep-29 Sep      116          75           --
    30 Sep-06 Oct       88          54           98
    07 Oct-13 Oct       67          89           43
    14 Oct-20 Oct      146          34           10
    21 Oct-27 Oct      114          65           --
    28 Oct-03 Nov       49          24           --
    04 Nov-10 Nov       21          69           --
    11 Nov-18 Nov       28          70           --
    19 Nov-24 Nov        1          46           --
    23 Dec-29 Dec       17          25           --

During 9 September-13 October glowing avalanches flowed 25-250 m toward Nanitu river (West Siau), and toward Beha river as far as 400 m from the crater rim. By the week of 14-20 October, the lava avalanches extended ~1.5 km toward the Nanitu river, 1.0 km toward the Beha river (West Siau), and 750 m toward the Kahetang river.

On 12 September loud noises were accompanied by a 50-m-high gray ash plume. During 5-6 October, there were 2 volcanic tremor events. On 19 October at 1759 an explosion ejected glowing material to a height of 500 m; it landed inside the crater. A gray-black ash plume reached up to 750 m, drifted to the N, and fell on the sea.

Activity decreased during November, and loud sounds were rarely heard. On 15 November at 0248 an ash explosion produced glowing material up to ~200 m that fell around the crater. Some of the material entered the Batang, Beha, and Keting rivers, located 300-350 m away. Ash fell around Salili, Beong, Hiu, Ondong, Pehe, and Paniki villages to the SW. The Alert Level remained at level 3 through at least 29 December (on a scale of 1 to 4).

Information Contacts: Volcanological Survey of Indonesia (VSI), Jalan Diponegoro No. 57, Bandung 40122, Indonesia (Email: dali@vsi.esdm.go.id, URL: http://www.vsi.esdm.go.id/).

05/2003 (BGVN 28:05) Ash explosions from January through May 2003

During 6 January-4 May 2003 explosions produced ash that fell on various parts of the crater. The S (main) crater emitted "white-gray ash" that reached 150-400 m high. On some nights, a red glow was visible reaching 25-50 m over the crater. The N crater emitted a "white-thin ash" plume that reached 50-300 m high. Fluctuating seismicity was dominated by multiphase earthquakes and emissions (table 7). The Alert Level remained at level 3 (on a scale of 1 to 4) through at least 4 May.

Table 7. Seismicity at Karangetang during 6 January-4 May 2003. Courtesy VSI.

    Date (2003)       Deep     Shallow    Explosions
                    volcanic   volcanic
                    (A-type)   (B-type)

    06 Jan-12 Jan      11         16          2
    13 Jan-19 Jan       9         16          2
    20 Jan-26 Jan      12         37         --
    27 Jan-02 Feb       6         28          1
    03 Feb-09 Feb      17         84          1
    10 Feb-16 Feb       9         30          1
    17 Feb-23 Feb       9         46         --
    24 Feb-02 Mar      48         68         --
    03 Mar-09 Mar      19         29          1
    10 Mar-16 Mar      14         11         --
    17 Mar-23 Mar      24        145         --
    24 Mar-30 Mar      21         68         --
    31 Mar-06 Apr       8         83         --
    07 Apr-13 Apr      18        143         --
    14 Apr-20 Apr      12        257         32
    21 Apr-27 Apr      13        373          2
    28 Apr-04 May      32        255         --

    Date (2003)      Multiphase   Emissions   Tectonic   Avalanches

    06 Jan-12 Jan       178          178         28          --
    13 Jan-19 Jan       133           42         40          --
    20 Jan-26 Jan       189           52         27          --
    27 Jan-02 Feb       228          118         22          --
    03 Feb-09 Feb       162          306         23          --
    10 Feb-16 Feb        85          102         16          --
    17 Feb-23 Feb        97            8         32          --
    24 Feb-02 Mar        78           17         34          --
    03 Mar-09 Mar        48            9         24         398
    10 Mar-16 Mar        27            7         30         125
    17 Mar-23 Mar        82            4         23           4
    24 Mar-30 Mar        35            1         33           2
    31 Mar-06 Apr        30           --         36          --
    07 Apr-13 Apr       116            6         50          --
    14 Apr-20 Apr       226           26         32           7
    21 Apr-27 Apr        93            6         17         309
    28 Apr-04 May       243            1         21          29

On 11 and 12 January, ash explosions at the S crater were accompanied by glowing material that reached 200 m high and scattered 500 m toward the E and W parts of the crater. An ash column rose up to 500 m above the crater. Two explosions at the S crater on 14 January produced an ash column up to 300 m high; glowing material rose up to 50 m and fell around the crater. Some of the material entered the Beha River, and ash fell into the sea E of the island. Explosions on 29 January and 6 February caused ashfall SW (Beong village) and SSW (Akesembeka village, Tarurane, Tatahadeng, Bebali, and Salili), respectively. A booming noise was heard frequently throughout the report period, and during early February was sometimes accompanied by thick gray emissions up to 350 m above the crater.

Beginning in early March, the booming noise was accompanied by glowing lava avalanches that traveled from the summit towards the Kahetang (1,250 m), Batuawang (750 m), Batang (1,000 m), and Beha (750 m) rivers. On 6 March an explosion from the S crater ejected ash 750 m high that fell in the E part of the crater. The noises and avalanches decreased during mid-to-late March.

An explosion on 15 April was followed by lava avalanches toward the W and S parts of the crater. A loud blasting sound was heard, and a dark-gray ash column reached 1,500 m. Ash fell to the E around Dame and Karalung villages, and over the sea. Lava avalanches from the S crater traveled 1,000 m toward the Batang and Batu rivers. On 20 April another explosion produced a 1,500-m-high ash column, and ash fell E over the sea. This explosion was followed by lava avalanches and a pyroclastic flow toward the Batang river that reached as far as 2,500 m. Lava avalanches extended 1,500 m down the S and W slopes. Blasting noises occurred for about 3 minutes.

On 22 April an explosion ejected ash and glowing material. The ash column reached 1,750 m and ash fell on the W slope, including Lehi, Mini, Kinali, and Hiung villages, while glowing material rose up to 750 m. This explosion was followed by lava avalanches towards the W and S that were accompanied by a pyroclastic flow toward the Batang river that extended 2,250 m. On 24 April, an explosion ejected ash to 750 m and ash fell eastward into the sea. Glowing material from the explosion traveled toward the W slope. During late April, the booming noises were once again accompanied by continuous glowing avalanches. These decreased during the first days of May.

Information Contacts: Volcanological Survey of Indonesia (VSI), Jalan Diponegoro No. 57, Bandung 40122, Indonesia (Email: dali@vsi.esdm.go.id, URL: http://www.vsi.esdm.go.id/).

07/2003 (BGVN 28:07) June 2003 ash plumes and two lava avalanches

Karangetang was the scene of volcanic and seismic unrest during early June 2003. The volcano produced ash plumes up to 400 m high and two lava avalanches.

In reports from the Volcanological Survey of Indonesia (VSI), activity for the week of 2-8 June 2003 was characterized by emissions of white-to-dark gray colored ash from the S crater, rising to 400 m. Observers at night noted a red glow up to 25 m over the crater. In the N crater, a white-colored gas emission rose to 150 m. During this week, a lava avalanche that occurred in the direction of the Batang river reached as far as 1000 m from the crater. There was a decrease in multiphase earthquakes compared to the previous week, but an increase in shallow volcanic earthquakes.

During the week of 9-15 June, white-colored gas emissions came from both the N and the S craters. Observers at night noted a continued red glow up to 25 m over the crater. Another lava avalanche occurred, this time traveling in the direction of the Beha river as far as 1000 m and toward the Batu Awang river as far as 250 m from the crater. There were increases in volcanic earthquakes and avalanche events.

The seismic record for 2-8 June suggested 11 deep volcanic earthquakes, 348 shallow volcanic earthquakes, 233 multiphase earthquakes, 46 emission earthquakes, 110 avalanches, and 26 tectonic earthquakes. The seismic record for 9-15 June noted 32 deep volcanic earthquakes, 438 shallow volcanic earthquakes, one explosion event, 228 multiphase earthquakes, 21 emission earthquakes, 447 avalanches, and 20 tectonic events. The volcano remained at alert level 2 (on a scale reaching a maximum of 4).

Information Contacts: Dali Ahmad and Nia Haerani, Volcanological Survey of Indonesia (VSI), Jalan Diponegoro No. 57, Bandung 40122, Indonesia (Email: dali@vsi.esdm.go.id, URL: http://www.vsi.esdm.go.id/).

09/2003 (BGVN 28:09) Ash explosions and lava avalanches in July; overall activity level declines

Ash explosions have been frequent at Karangetang during 2003 (BGVN 28:05 and 28:07). A red glow at night and lava avalanches were reported during 9-15 June (BGVN 28:07). Although detailed observations were not provided by the Volcanological Survey of Indonesia (VSI) for the next two weeks, the hazard status remained at Alert Level 2 (on a scale of 1-4).

VSI weekly reports from 30 June through 3 August indicated that white gas plumes from the S crater typically rose 350-500 m above the crater rim, night glow often extended 25 m above the crater, and white gas plumes from the N crater rose as high as 350 m. Seismic data showed that lava avalanches and shallow volcanic earthquakes in early July were significantly reduced compared to the first half of June (table 8).

Table 8. Seismicity at Karangetang during 2 June-28 September 2003. VSI did not issue reports for Karangetang during weeks not included in the table; a dash indicates no data reported. Courtesy of VSI.

    Date (2003)     Deep  Shallow  Explosion  Multiphase  Emission  Avalanches  Tectonic
                    Vol     Vol

    02 Jun-08 Jun    11     348       --          233        46         110        26
    09 Jun-15 Jun    32     438        1          228        21         447        20

    30 Jun-06 Jul    15      93       --          446        11          32        11
    07 Jul-13 Jul    15      93       --          534        22          35         7
    14 Jul-20 Jul    21     174       31          672        38          45        22
    21 Jul-27 Jul    17     112        9           94       131          66        25
    28 Jul-03 Aug    10       8       --          312       174          94        10

    01 Sep-07 Sep     8      44        1           80       341           1        20
    08 Sep-14 Sep     5      14        0           50       266           5        23
    15 Sep-21 Sep     6      90        0            3        16           0        74
    22 Sep-28 Sep     9      60        0           75       130           0        37

During 18-20 July there were ash-producing explosions and lava avalanches. On 21-22 July an ash explosion produced a 150-m-high ash column and a glowing lava avalanche flowed 350 m toward the Beha river. During the week of 28 July-3 August another glowing lava avalanche flowed 1,500 m toward the Beha river and 350 m toward the Batang river. On 29 July volcanic tremor was recorded with a maximum amplitude of 0.5-2 mm.

Karangetang was not included in August reports, but the report for 1-28 September noted white gas emissions from the S crater rising 150-350 m and red glow at night reaching 25 m over the crater, with the N crater exhibiting white gas emissions to 50-150 m above the crater. There were no lava avalanches during this period. The Alert Level remained at 2.

Information Contacts: Dali Ahmad, Hetty Triastuty, and Nia Haerani, Volcanological Survey of Indonesia (VSI), Jalan Diponegoro No. 57, Bandung 40122, Indonesia (Email: dali@vsi.esdm.go.id, URL: http://www.vsi.esdm.go.id/).

10/2003 (BGVN 28:10) White gas emissions and glow during October, but decreased seismicity

Explosive activity has been common at Karangetang in recent years, producing ashfall and lava avalanches as recently as May and June 2003 (BGVN 28:05 and 28:07). However, Karangetang was not included in reports by the Volcanological Survey of Indonesia (VSI) between 16 June and 28 September 2003. A report for the week of 29 September-5 October indicated that there had been a decrease in multiphase and emissions earthquakes compared to the previous week (table 9). At that time white gas emissions were observed rising 400 m above the S crater and 50 m above the N crater. Red glow was seen at night over the S crater that week. No lava avalanches occurred. Similar observations were reported through 19 October. Although surface observations of activity were consistent, seismic data showed that shallow volcanic earthquakes increased and emission events decreased during 6-19 October. The hazard status remained at Alert Level 2 (on a scale of 1-4) through at least 19 October.

Table 9. Seismicity at Karangetang during 2 June-19 October 2003. Courtesy of VSI.

    Date (2003)       Deep     Shallow    Multiphase   Emission   Tectonic
                    Volcanic   Volcanic

    02 Jun-08 Jun      11        348          233         46         26
    09 Jun-15 Jun      32        438          228         21         20
    16 Jun-28 Sep    No data available
    29 Sep-05 Oct      15         84           50        121         38
    06 Oct-12 Oct      19        103           33         74         32
    13 Oct-19 Oct      18        135           54         72         33

Information Contacts: Dali Ahmad, Hetty Triastuty, Nia Haerani, and Suswati, Volcanological Survey of Indonesia (VSI), Jalan Diponegoro No. 57, Bandung 40122, Indonesia (Email: dali@vsi.esdm.go.id, URL: http://www.vsi.esdm.go.id/).

11/2003 (BGVN 28:11) Ash explosion on 28 October, then decreased seismicity

White gas emissions and glow were reported at Karangetang during October 2003. The Volcanological Survey of Indonesia (VSI) reported continuing activity over the period 26 October-30 November, with white gas plumes rising 350-400 m above the S crater rim and 50-150 m above the N crater. On 28 October an ash explosion produced a 2,000-m-high column with ashfall reaching the sea to the E and a lava avalanche toward the Batu Awang area, 750 m from the summit. Except for the week of 17-23 November, local seismicity decreased compared to the first half of October (table 10). The hazard status remained at Alert Level 2 (on a scale of 1-4).

Table 10. Seismicity at Karangetang during 27 October-30 November 2003 One explosion and one avalanche also occurred during the week of 27 October-2 November. Courtesy of VSI.

    Date (2003)        Deep      Shallow    Multiphase   Emission   Tectonic
                     Volcanic   Volcanic

    27 Oct-02 Nov       18          64          10          24          43
    03 Nov-09 Nov        9          96           7          12          53
    10 Nov-16 Nov        3          52          10          23         106
    17 Nov-23 Nov       25         135          16          42          47
    24 Nov-30 Nov       15          79          34          29         130

Information Contacts: Dali Ahmad, Hetty Triastuty, Nia Haerani, and Suswati, Volcanological Survey of Indonesia (VSI), Jalan Diponegoro No. 57, Bandung 40122, Indonesia (Email: dali@vsi.esdm.go.id, URL: http://www.vsi.esdm.go.id/).

03/2004 (BGVN 29:03) Aviation report, stating ash to 7.5 km; seven MODIS alerts in ~ 1 year

A Darwin Volcanic Ash Advisory Centre report stated that at 0630 UTC (1430 local time) on 18 July 2003 pilots saw a thick ash plume rising from the volcano to ~ 8.5 km altitude.

HIGP MODIS thermal-alert reports for the year to 13 April 2004 showed, subject to the limitations of thermal imaging (e.g. in times of heavy cloud), thermal activity at the volcano on 26 April, 7 and 30 May, 1 and 6 June, 21 July and 11 August 2003, and 2 April 2004.

Information Contacts: HIGP MODIS Thermal Alert System, Hawaii Institute of Geophysics and Planetology, School of Ocean and Earth Science and Technology, University of Hawaii at Manoa (URL: http://modis.higp.hawaii.edu/); Darwin Volcanic Ash Advisory Centre (VAAC), Commonwealth Bureau of Meteorology, Northern Territory Regional Office, PO Box 40050, Casuarina, NT 0811, Australia (URL: http://www.bom.gov.au/info/vacc/, Email: darwin.vaac@bom.gov.au).

05/2005 (BGVN 30:05) Ongoing seismicity during January-February 2005; lava avalanche in January

Ongoing seismicity continued at Karangetang during January-February 2005. Lava avalanches were noted on 3 January and during the week of 17-23 January. The volcano was last discussed in a report on thermal alerts and a pilot's report of an ash plume to 7.5 km altitude (BGVN 29:03, which updated through May 2004). Table 11 presents a summary of the reported seismic and other data during January and February 2005.

Table 11. A summary of observations made at Karangatang during 3 January-February 2005. Courtesy of DVGHM.

    Date       Volcanic   Volcanic   Multi-   Emission   Tremor       Lava       Tectonic   Alert
                   A          B      phase                          Avalanches              Level

    03 Jan         3         10         2         2      0.5-3 mm        5           8        3
    04 Jan         9          4        --        --      0.5-1 mm       --           7        3
    05 Jan         2         11         1        --         --          --           3        3
    17-23 Jan     61        125         6        --         --          36          36        3

Information Contacts: DVGHM (see Egon).

05/2007 (BGVN 32:05) Frequent activity since 2004, including lava emission and pyroclastic flows

Since the end of an eruptive period in October 2003 (BGVN 28:11 and 29:03), recent activity has been centered at Crater I (S crater) and Crater II (N crater), of the five summit craters (figure 5). Activity since late 2003 has included ash plumes, lava flows, lava avalanches, and pyroclastic flows. There have been five periods when thermal anomalies were detected in MODIS satellite data from January 2004 through March 2007 (figure 6). However, the gaps between such episodes may in part be caused by clouds obscuring the summit, so they cannot be correlated to eruptive episodes. Intermittent reports made available by the Center of Volcanology and Geological Hazard Mitigation (CVGHM) since June 2004 provide additional observations and seismic data, and sometimes note eruptive activity during periods of gaps in MODIS thermal anomalies. These reports are also not provided on a regular basis, and the lack of reports for a time period does not necessarily indicate a lack of activity.

Figure 5. Topographic map and N-S profiles of Karangetang showing the five summit craters. Craters I (KI) and II (KII) are currently active. The topographic base map is from 1962; roughly N-S profiles are from 1992 (top) and July 2001 (bottom), showing the changes caused by dome growth. Courtesy of CVGHM.
Figure 6. Plot showing days with MODIS thermal anomalies during January 2004-February 2007. Scale indicates the five arbitrary thermal anomaly periods, and does not reflect anomaly magnitudes. Eruptive activity was also reported on some occasions during gaps in thermal anomalies. Compiled from MODIS/HIGP data.

Activity during April-November 2004. After a single thermal anomaly on 5 April 2004, another nine anomalies were seen in MODIS data during 5 May to 29 June. Observations provided by the CVGHM indicated continuing activity during this period. Reports from 31 May onward through 29 August noted that activity was centered at Crater I, but visual observations were often prevented by fog. On clear days white plumes rose 100-400 m above the crater rim. Incandescent glow seen at night reached 10-25 m above the summit. At Crater II, diffuse white plumes reached 25-50 m above the rim. During the three weeks of 9-29 August the reports also included observations of incandescent material and sounds of lava avalanches. Ten avalanche signals were recorded the week of 16-22 August. Shallow B-type volcanic earthquakes also increased significantly (table 12).

Table 12. Seismicity at Karangetang during 24 May-29 August 2004. Courtesy of CVGHM.

    Date                  Volcanic    Volcanic    Multi-phase
                           A-type      B-type

    24 May-30 May 2004        4          12            5
    31 May-06 Jun 2004       10          35            7
    07 Jun-13 Jun 2004       22          22            4
    14 Jun-20 Jun 2004       11          22            4
    21 Jun-27 Jun 2004       45          49           13
    28 Jun-04 Jul 2004        6           7            3
    05 Jul-11 Jul 2004       16          30            1
    12 Jul-18 Jul 2004       11          29            3
    19 Jul-25 Jul 2004       11          18           16
    26 Jul-01 Aug 2004       14          12            2
    02 Aug-08 Aug 2004       12          75           11
    09 Aug-15 Aug 2004       86         259           60
    16 Aug-22 Aug 2004       10         153           74
    23 Aug-29 Aug 2004        9          56           68

Between 16 October and 26 November 2004, thermal anomalies were again frequent. On 25 October the hazard status was raised due to increasing volcanism over the previous two days. A larger area of incandescence was noted at the summit, and a lava flow descended 800 m. No other reports of observations were available between September and November 2004.

Activity during January-March 2005. Thermal anomalies reappeared in MODIS satellite data on 6 February 2005, and continued to be detected on an almost daily basis through 24 March. CVGHM reports noted lava avalanches starting on 3 January 2005, accompanied by booming noises. During 24-30 January white gas plumes were emitted 50 m above both craters, and a 10- m-high glare was observed at night inside the plume from Crater II. Lava avalanches since 26 January originated from the lava-flow front, moving 750-1,200 m towards the Beha Barat River, 750-2,200 m towards the Batu Awang River, and 1,750 m towards the Kahetang River.

Lava avalanches in the first half of February had run-out distances of 1,250 m down the Beha River drainage, 700 m down the Batu Awang, 1,750 m down the Kahetang, and 1,200 m down the Nanitu. Incandescent material during this period was ejected ~25 m into the air and fell back into the crater. On 16 February, a lava flow advanced 600 m from the crater towards the Nanitu River. A pyroclastic flow later that evening from the lava front traveled 3.4 km and reached the sea, ~4 km from the summit. Lava avalanches from flow-fronts continued into late February toward the Beha, Kahetang, Batu Awang, and Nanitu drainages to distances of 500-1,200 m. These avalanche events produced continuous booming sounds and also "glowing bursts" to heights of 10-25 m. Gas emitted from Crater I rose 50-200 m, and a glare could be seen inside the gas column to heights of 25-75 m. Crater II also produced gas emissions 50-150 m high.

No additional reports are available until a mid-April 2005 report indicated that the volcano was still at a Level III hazard status. During clear weather over 2-9 May, a 400-m-high white gas plume rose from Crater I; there was a 25-m-high glare inside it. Meanwhile, Crater II emitted a white gas plume as high as 100 m. Due to the continuing possibility of pyroclastic avalanches and lahars during the rainy season, residents were not allowed within 2 km of the edge of the lava flow. On 30 May, based on a pilot observation, the Darwin VAAC reported ash at a height below 3 km drifting E; however ash was not visible on satellite imagery.

Activity during August-December 2005. The Darwin VAAC again issued an ash advisory on 2 August regarding a plume to an altitude of 4.6 km. This ash cloud, which continued through 4 August without significant interruptions, was occasionally discernable on both MTSAT and NOAA -12 satellites. Between 26 September and 16 October CVGHM reports again noted white gas rising 200-250 m from Crater I with a 25-m-high glare at the bottom of the gas column, and a 150-m gas emissions from Batukole crater. Tremor continued during 30 November-13 December 2005, but no other activity was described. Karangetang remained at Alert Level 3.

Activity during July-September 2006. Single MODIS thermal anomalies were seen on 11 February 2006, 18 May, and 8 June. Hot spots were then seen almost daily during 13 July-30 September. The Darwin VAAC noted a small eruption on 3 July 2006 with an ash plume to an altitude of 3.7 km observed on satellite imagery. On 12 July, lava flows were moving E toward the Kahetang and Batu Awang rivers, reaching a maximum distance of 2 km. White emissions rose 600 m above the crater. Having previously been lowered, the hazard status was raised from 2 to 3 on 13 July, and then to Alert Level 4 on 22 July due to increased eruptive activity. Lava flows 1.8 km from the vent were observed on 20 July moving E toward the Kahetang and Batu Awang rivers, were 2 km long towards the Keting River, and 400 m S towards the Bahembang River.

On 21 July, a pyroclastic flow from the upper S flank traveled 2.5 km toward the Batu Awang River and was followed by lava flows that traveled toward the Keting and E towards the Kahetang rivers, reaching a maximum runout distance of 2 km. On 22 July, Electronic Distance Measurement equipment indicated deformation measurements indicative of a bulge of about 3-5 mm. Diffuse white smoke was seen at a height of ~350 m above the summit. Lava flows traveled a maximum distance of ~2.3 km towards the Keting and S towards the Bahembang rivers during 22-23 and 25 July.

On 1 and 2 August 2006, lava flows traveled up to 500 m E toward the Batu Awang river and 300-750 m S towards the Keting River and white plumes reached heights of 50-300 m above the summit. Incandescent rockfalls originating from the summit and termini of the lava flows traveled 500-1,500 m E toward the Kahetang and Batu Awang rivers, S towards the Keting River, and occasionally 500 m S towards the Batang River. During 3-4 August, lava flows traveled up to 500 m E toward the Batu Awang river and 100-750 m S towards the Keting. During 7-13 August, lava flows again advanced E toward the Batu Awang river. Incandescent rockfalls originating from ends of the lava flows were also observed.

Activity from mid-August through September 2006 was relatively uneventful. The Darwin VAAC reported and ash cloud on 11 September. On 24 November the Darwin VAAC, reported an eruption that produced a small ash plume observed on satellite imagery that reached an altitude of 3 km.

Activity during November 2006-April 2007. After about six weeks without being detected, thermal anomalies were again frequently seen from 17 November through 11 January 2007. On 14 February the Alert Level was reduced from 3 to 2. Tremor events were recorded at a rate of 52/day over the previous two months, but had not increased since the 21 July 2006 pyroclastic flows, and earthquakes were shallow. Crater I continued to emit a thin trace of white gas 100-300 m above the crater rim. Emissions from Crater II rose to 50-250 m, with occasional incandescence up to 50 m.

Karangetang was relatively quiet until 28 March when a gas cloud was observed up to 100 m above the crater rim. According to a news article in the Jakarta Post, increased activity starting on 26 March led to the emission of "hot clouds" over the next two days. Based on satellite imagery and analysis from the US Geological Survey, the CVGHM reported that sometime between mid-March and 6 April the lava dome in the northern crater had collapsed and was replaced by a new dome ~40 m in diameter. A MODIS thermal anomaly was detected on 3 April. During 23-29 April only dense white plumes were observed from Crater II.

Information Contacts: Center of Volcanology and Geological Hazard Mitigation (CVGHM), Jalan Diponegoro 57, Bandung 40122, Indonesia (URL: http://portal.vsi.esdm.go.id/joomla/); Hawai'i Institute of Geophysics and Planetology (HIGP) Hot Spots System, University of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://hotspot.higp.hawaii.edu/); Darwin Volcanic Ash Advisory Centre (VAAC), Bureau of Meteorology, Northern Territory Regional Office, PO Box 40050, Casuarina, Northern Territory 0811, Australia (URL: http://www.bom.gov.au/info/vaac/); Jakarta Post, Indonesia (URL: http://www.thejakartapost.com/).

08/2007 (BGVN 32:08) Eruptions during mid-2007; evacuations; pyroclastic flows; lava avalanches

The previous Bulletin report (BGVN 32:05) discussed periodic activity at Karangetang from January 2004 through April 2007. This report updates activity through August 2007. The island (Ulau Siau, or Siau) has a tear-drop-shape, widest at the N end with the tail bent E. The island's maximum E-W extent is about 10 km.

During April through mid August 2007, the Center of Volcanology and Geological Hazard Mitigation (CVGHM) recorded mild activity with periodic tremor activity registering at 0.5-2 mm and "thick-white-ash" periodically being ejected 25-750 m above the Main crater.

On 25 June 2007, an incandescent explosion 750 m high was observed and a lava avalanche traveled 1,000 m down the to Nawitu river and 400 m down the Bahambang river. Some materials descended into the Batuawang Valley.

Beginning 5 August 2007, the CVGHM recorded tremors with amplitude 4 mm in the vicinity of Karangetang. On 8 August, tremor amplitude increased to 23 mm and a lava fountain rose up to 25-75 m above the summit. Additional lava and pyroclastic flows observed on 10 August prompted authorities to evacuate more than 500 people from villages on the flanks.

On 11 August, because observers witnessed increased eruptive activity, and seismicity included tremors increasing to 46 mm in amplitude, the CVGHM raised the alert status from 2 to 3 (on a scale of 1-4). The alert status was again raised on 18 August from 3 to 4 as the CVGHM reported tremor (45-47 mm amplitude), lava emission, and a debris-flow about 2 km down the S flank. "Booming" noises were also heard and thick ashfall covered villages, farms, and trees on the flanks. Based on these advisories the Darwin Volcanic Ash Advisory Center notified aviation interests of the potential for a major eruption.

On 19 August, Karangetang erupted again several times. An avalanche of lava and hot ash poured down the flanks. Avalanches reportedly reached the coastal villages of Karalung (several kilometers SE of the summit) and Hiung (several kilometers NW of the summit). After 19 August eruptive activity decreased and on 30 August the hazard status was dropped to 3.

Thermal anomalies were detected by MODIS beginning 6-8 August with major activity occurring on 10 August and nearly continuous activity from 13 August through 2 September.

Information Contacts: Center of Volcanology and Geological Hazard Mitigation (CVGHM), Saut Simatupang, 57, Bandung 40122, Indonesia (URL: http://portal.vsi.esdm.go.id/joomla/); Hawai'i Institute of Geophysics and Planetology (HIGP) Hot Spots System, University of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://hotspot.higp.hawaii.edu/); Darwin Volcanic Ash Advisory Centre (VAAC), Bureau of Meteorology, Northern Territory Regional Office, PO Box 40050, Casuarina, Northern Territory 0811, Australia (URL: http://www.bom.gov.au/info/vaac/); Jakarta Post, Indonesia (URL: http://www.thejakartapost.com/).

01/2009 (BGVN 34:01) A 2007 plume rose to 12.2 km altitude; incandescent rockfalls

The August 2007 eruptive activity reported in BGVN 32:08 subsided at the beginning of September 2007. Accordingly, the Center of Volcanology and Geological Hazard Mitigation (CVGHM) lowered the hazard alert status from 4 to 3 (on a scale of 1-4). The next notable observation was a report from the Darwin Volcanic Ash Advisory Center (VAAC) of a possible eruption on 4 October 2007 based on satellite imagery of a plume that rose to 12.2 km altitude.

On 13 and 21 October 2007, the Darwin VAAC reported that pilots had observed ash plumes at altitudes near that of the summit. Minor tremor was recorded on 30 October, and the crater continued to emit diffuse white plumes up to 100 m above the crater. On 23 November CVGHM lowered the alert status from 3 to 2 due to a decrease in both seismicity and observed plume height and density.

A pilot observation of a low-level ash plume on 12 March 2008 was reported by the Darwin VAAC. On 28 November 2008, CVGHM reported that increased seismicity indicated rockfalls, along with white plumes from summit craters I and II. On 29 November white and brownish plumes were emitted to low altitudes. Incandescent rockslides from the main crater traveled 250 m S towards the Bahembang River, 250 m W towards the Beha Timur River, and 500-1,000 m S towards the Keting River. Thunderous noises were reported.

Fog prevented visual observations on 30 November, but the seismic network recorded 160 rockfalls. On 1 December, incandescent rockslides traveled 250 m S towards the Bahembang River, 750 m W towards the Beha Timur River, and 500-1,500 m S towards the Keting River. On 2 December, the Alert Level was raised to 3 due to the continuation of elevated seismicity, the appreciable run-out distances of incandescent rockslides, and the height of incandescent material ejected from the summit.

Based on satellite imagery and CVGHM, the Darwin VAAC reported that on 2 December 2008 an ash plume rose to 3 km altitude and drifted W. MODVOLC thermal alerts were detected during 6 August-2 September 2007 and 2 December 2008-25 February 2009.

Information Contacts: Center of Volcanology and Geological Hazard Mitigation (CVGHM), Jalan Diponegoro 57, Bandung 40122, Indonesia (URL: http://portal.vsi.esdm.go.id/joomla/); Hawai'i Institute of Geophysics and Planetology (HIGP) Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://hotspot.higp.hawaii.edu/); Darwin Volcanic Ash Advisory Centre (VAAC), Bureau of Meteorology, Northern Territory Regional Office, PO Box 40050, Casuarina, NT 0811, Australia (URL: http://www.bom.gov.au/info/vaac/); Agence France-Presse (URL: http://www.afp.com/).

05/2009 (BGVN 34:05) Elevated seismicity, lava flows in May 2009; high alert, evacuations

Lava flows from Karangetang (figure 7) reached several kilometers in length by the end of May 2009, and some residents evacuated. Witnessed plumes were minor, many below 100 m above the summit, the tallest 700 m above the summit. Intermittent minor activity, including explosions, ashfall, and thermal anomalies, has continued in the last few years (BGVN 32:05, 32:08, 34:01), with no significant changes since 2007 (figures 8 and 9).

Figure 7. Map of the islands in the region around Karangetang, including Java, Bali, and Sulawesi (Celebes). Karangetang resides at upper right on Siau island, which is ~ 24-km-long, too small to see at this scale. (inset) An enlarged satellite image of Karangetang; white areas are clouds over volcanic peaks on the island. Maps have N directly upwards; scale bars are at lower left. Both maps courtesy of Google Earth.
Figure 8. A 2007 photo of Karangetang taken from the sea (direction unspecified) showing multiple peaks and abundant unvegetated lava flows of young ages. The more distant cone may have been steaming. Photo by Mark Tolosa.
Figure 9. A photo of the summit area at Karangetang taken from the observatory station at Salili, S of the volcano, on 13 August 2007. Lava flows and rock avalanches during 2007 were not directly visible from this point. Note the rugged topography of the active lava dome at the summit. Courtesy of Arnold Binas.

Based on a pilot observation, the Darwin VAAC reported that on 24 May an ash plume from Karangetang rose to an altitude of 3.7 km and drifted 75 km S. This was the tallest plume of the reporting interval.

On 31 May, based on seismicity, an increase in both volcanic tremor, and continuous air blasts (accompanied by rumbling sounds), the Center of Volcanology and Geological Hazard Mitigation (CVGHM) upgraded Karangetang's hazard status from Alert Level 3 (Siaga) to 4 (Awas) the highest level (figure 10). According to the website "Natural Disasters in Indonesia," hundreds of people were evacuated from near the volcano and the total number of vulnerable residents was 3,000. The Alert Level fell back to 3 on 9 June.

Figure 10. Alert levels applicable to Karangetang (and commonly used in Indonesia) with brief explanation of their significance. From the Natural Disasters in Indonesia website.

Tremor was reported on 30 May and became continuous at times during the morning of 31 May (0600-1200). That same time interval saw the largest number of earthquakes. Craters I and II initially produced white plumes to heights of ~ 10-25 m and visible incandescence.

Beginning at 0630 a dense white to brownish plume from the principal crater reached a height of ~ 100 m above the peak. At 0824 there was a continuous expulsion of lava which flowed S, traveling ~ 2.3 km down the Kali Batuawang river. Lava also flowed ~ 1.5 km into the Kali Kahetang and Kali Keting rivers. Lava flows periodically traveled ~ 1 km down the Kali Nanitu and Batang rivers. At 0828 a thick grayish to plume was continuously ejected to a height of ~ 25-700 m accompanied by a rumbling sound of low to medium intensity.

In connection with the upgrading of the hazard status to Alert Level 4, CVGHM stepped up its monitoring and sent a team to the field. The regional government was alerted to the possible fallout of hot ash and the expulsion of lava flows. Numerous threatened towns and sub-districts were mentioned. These included Siau Timur, Kampung Kola-Kola (Bebali village); Kampung Bolo and Kampung Kopi, (Tarorane village); Kampung Hekang, Tatahadeng village, the village of Dame 1, the village of Karalung along the Kali Beha Timur river and, Kampung Dompase, along the banks of the Kali Nanitu and Kali Kinali rivers. There was the constant threat of lahar (mud flows) along the length of the rivers that originate from the active crater, including the Batu Awang, Kahetang, Keting, Batang, Beha Timur, and Nanitu rivers.

People were cautioned not to approach Karangetang closer than 3 km from the summit, particularly under conditions of heavy rain. Residents of the village of Dame and part of the population of the township of Tatahadeng were advised to maintain a high level of alertness to the dangers of pyroclastic flows and lava flows. In the case of sudden tephra falls, authorities recommended the public don face masks. As previously mentioned, on 9 June 2009 the alert level was reduce from 4 to 3.

MODVOLC. There were numerous MODVOLC thermal alerts during 2 December 2008-25 February 2009 (BGVN 34:01). As of late June 2009, dates of subsequent MODVOLC alerts for Karangetang were 18 and 29 March; 25, 26, 28, and 30 April; and 7, 14, and 31 May; and 3 June. In effect, the alerts were broadly spread for more than a year and showed little if any response to the elevated activity seen during the crisis.

Information Contacts: Center of Volcanology and Geological Hazard Mitigation (CVGHM), Jalan Diponegoro 57, Bandung 40122, Indonesia (URL: http://portal.vsi.esdm.go.id/joomla/); Hawai'i Institute of Geophysics and Planetology (HIGP) Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://hotspot.higp.hawaii.edu/); Darwin Volcanic Ash Advisory Centre (VAAC), Bureau of Meteorology, Northern Territory Regional Office, PO Box 40050, Casuarina, NT 0811, Australia (URL: http://www.bom.gov.au/info/vaac/); Agence France-Presse (URL: http://www.afp.com/); Arnold Binas, Toronto, Canada (Email: abinas@gmail.com, URL: http://www.summitpost.org/user_page.php?user_id=42443, http://www.flickr.com/photos/hshdude/collections/72157600584144439/).

01/2010 (BGVN 35:01) Lava flows and pyroclastic flows seen during 2009

At Karangetang during May 2009, emissions included explosions and lava flows (BGVN 34:05). Activity continued during June and into at least early 2010.

During the first week of June 2009, lava flows from Karangetang traveled 50 m E and 600 m SE. According to the Center of Volcanology and Geological Hazard Mitigation (CVGHM), incandescent rocks from the main craters and ends of the lava flow traveled as far as 2 km towards multiple river valleys, including the Keting River to the S. On 1 June, white-to-gray-to-brown plumes rose 700 m above the main crater. Incandescent lava was ejected 500-700 m. On 4 June, both the tremor amplitude and the number of earthquakes decreased. During 4-6 June, white plumes rose 50-300 m from the main crater. On 7 and 8 June, fog often prevented observations and incandescent rocks were rarely seen. The Alert Level was lowered to 3 (on a scale of 1-4) on 9 June.

No further activity was reported until 3 November 2009. Based on a pilot observation and satellite imagery, the Darwin Volcanic Ash Advisory Centre (VAAC) reported that on 3 November an ash plume rose to an altitude of 3 km and drifted 90-185 km W.

According to news reports, a pyroclastic flow and a lahar descended the flanks on 4 November. Residents saw active lava flows the next day. On 11 November, incandescent material was ejected 5 m into the air.

CVGHM noted that seismicity declined during 1 January-8 February 2010. When the weather was clear, white plumes were seen rising 100-200 m above the crater rim. Incandescent material was ejected 10-50 m above the Utama Crater. CVGHM lowered the Alert Level to 2 on 12 February.

MODVOLC. MODVOLC thermal alerts that were previously reported in March through 3 June 2009 (BGVN 34:05) continued through 8 November. Alerts were recorded on 10 July, 5 September, 5 October, 16 October, 30 October, 3 November (4 pixels on Aqua, 4 pixels on Terra), 4 November (2 pixels on Terra, 1 pixel on Aqua), and 8 November. No alerts were recorded between 8 November 2009 and 19 February 2010.

Information Contacts: Center of Volcanology and Geological Hazard Mitigation (CVGHM), Jalan Diponegoro 57, Bandung 40122, Indonesia (URL: http://portal.vsi.esdm.go.id/joomla/); Hawai'i Institute of Geophysics and Planetology (HIGP) Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://hotspot.higp.hawaii.edu/); Darwin Volcanic Ash Advisory Centre (VAAC), Bureau of Meteorology, Northern Territory Regional Office, PO Box 40050, Casuarina, NT 0811, Australia (URL: http://www.bom.gov.au/info/vaac/); Berita News (URL: http://berita.liputan6.com/).

02/2011 (BGVN 36:01) Eruption in August 2010 isolated 20,000 residents and caused four deaths

A sudden eruption at Karangetang on 6 August 2010 occurred without warning and caused considerable damage. This report covers the interval from 6 August 2010 to mid-March 2011. Previously, the Indonesian Center of Volcanology and Geological Hazard Mitigation (CVGHM) had reported that, after explosions and lava flows during May and June 2009 and a pyroclastic flow and lahar in November 2009, seismicity had declined through early February 2010 (BGVN 35:01). On 12 February 2010, CVGHM had lowered the Alert Level to 2 (on a scale of 1-4).

According to news articles, an explosion on 6 August 2010 ejected hot clouds of gas and sent pyroclastic flows down the W flank. At least one house was buried and several other buildings, including a church, were damaged. A damaged bridge isolated about six villages and their ~20,000 residents, and communication links were lost. According to news reports (CNN and Associated Press), four people were confirmed dead and five were injured, and about 65 were evacuated. The Darwin Volcanic Ash Advisory Centre (VAAC) reported that an ash plume rose to an altitude of 9.1 km and drifted W on that same day.

The news reports cited CVGHM official Priyadi Kardono as noting that the volcano erupted just after midnight when water from heavy rains had penetrated the volcano's hot lava dome, causing the explosion. According to these reports, Kardono said volcanologists did not issue a warning about the eruption because there were no indications of increased volcanic activity. Kardono also noted that the explosion was not large, and the flow of volcanic debris had since decreased.

CVGHM reported that during 1-21 September 2010, lava traveled 75-500 m down Karangetang's flanks and avalanches traveled as far as 2 km down multiple drainages, to the S, E, and W. Incandescent material was ejected up to 500 m above the crater. Ashfall was reported in areas to the NW.

On 21 and 22 September incandescent material traveled down multiple drainages. Strombolian activity was observed on 22 September; material ejected 50 m high fell back down around the crater. That same day, the Alert level was raised to 3.

During November and early December 2010, CVGHM noted a drastic decrease in the occurrence of pyroclastic flows on Karangetang's flanks. Seismicity also decreased. The only reports were of white plumes that rose up to 300 m above the craters. The Alert Level was thus lowered to 2 on 13 December 2010.

According to CVGHM, the Alert Level was again raised from 2 to 3 on 11 March 2011 due to increased seismicity. According to news reports, lava flows were visible and blocks originating from the lava dome traveled as far as 2 km down the flanks, along with hot gas clouds. A Reuters News photo published in Okezone News showed a moderate Strombolian eruption venting from the summit on 11 March, with an apron of incandescent spatter dotting the upper slopes, and a swath of red spatter and bombs bouncing down one flank. Darwin VAAC reported that on that same day, an ash plume rose to an altitude of 2.4 km and drifted 55 km SW; on 13 March, another ash plume rose to an altitude of 3.7 km and drifted 37 km.

During 12-16 March, CVGHM stated that bluish gas plumes rose 50-150 m above the main crater. On 17 March lava flows traveled as far as 2 km from the main crater, accompanied by roaring and booming noises.

On 18 and 20 March lava flows traveled 1.5-1.8 km and collapses from the lava flow fronts generated avalanches that moved another 500 m. Avalanches from the crater traveled 3.8 km down the flanks. Multiple pyroclastic flows about 1.5-2.3 km long destroyed a bridge, damaged a house, and trapped 31 people (later rescued) between the flow paths. Later that day, pyroclastic flows traveled 4 km, reaching the shore. The Alert Level was raised to 4. According to news articles, 600-1,200 people were evacuated from villages on the W flank.

During the week after 20 March, seismicity and deformation declined. The number of new lava flows also declined.

MODVOLC Thermal Alerts. Thermal alerts derived from the Hawai'i Institute of Geophysics and Planetology Thermal Alerts System (MODVOLC) were reported through 19 February 2010 in BGVN 35:01. A significant number of alerts were measured on 19 March 2010 (14 pixels at 0215 UCT on Terra) and 23 March (1 pixel on Aqua), followed by ~5 months without measured alerts. Alerts reappeared during 16 August-19 October 2010. Alerts were absent between 20 October 2010 and 10 March 2011, followed by renewed alerts during 11-12 March 2011.

Information Contacts: Center of Volcanology and Geological Hazard Mitigation (CVGHM), Jalan Diponegoro 57, Bandung 40122, Indonesia (URL: http://portal.vsi.esdm.go.id/joomla/); Darwin Volcanic Ash Advisory Centre (VAAC), Bureau of Meteorology, Northern Territory Regional Office, PO Box 40050, Casuarina, NT 0811, Australia (URL: http://www.bom.gov.au/info/vaac/); Hawai'i Institute of Geophysics and Planetology (HIGP) MODVOLC Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://hotspot.higp.hawaii.edu/); Okezone News (URL: http://news.okezone.com/read/2011/03/12/340/434280/gunung-muntahkan-lava-pijar); Associated Press (URL: http://www.ap.org/); Reuters (URL: http://www.reuters.com/); CNN (URL: http://www.cnn.com/); Straits Times (URL: http://www.straitstimes.com/); Novinite (URL: http://www.novinite.com/).

01/2014 (BGVN 39:01) 2011 into 2014: Spatter at crater, lava flows, and ash plumes

Our last Bulletin report (BGVN 36:01), covered the interval from 6 August 2010 to late-March 2011. This report covers activity for 21 March 2011 through 9 February 2014. During this interval, eruptions clearly took place in March and April 2011, in May 2012, and in April 2013. Crater glow was seen in July, and again during late August to early September 2013, suggesting eruptions. The next report came 9 February 2014, again indicating an eruption then. MODVOLC data discussed at the end also supplements this eruptive information. Highlights include several episodes of abundant alerts and several intervals with pauses, including a 10 month pause that ended on 17 May 2012.

2011. The Center of Volcanology and Geological Hazard Mitigation (CVGHM) reported that during 21-23 March incandescent material from Karangetang was ejected 50-75 m above the crater. Lava flows traveled as far as 2 km and collapses from the lava-flow fronts generated avalanches that moved down the flanks at most another 300 m. On 24 March lava was incandescent in areas 1.5 km away from the crater. Incandescent material from the lava-flow fronts rolled an additional 200-500 m down the flanks. Incandescent material was again ejected 75 m above the crater. Later that day, due to decreased seismicity and a decline in the rate of lava flows, the Alert Level was lowered to 3 (on a scale of 1-4).

CVGHM reported that during 30-31 March incandescence emanated from Karangetang's main crater as well as bluish and white gas plumes. Lava flows originating from the main crater traveled 2 km down the flanks. Incandescent avalanches from the main crater and from the lava-flow fronts traveled up to 1.8 km down the flanks. On 31 March a thunderous sound was accompanied by a gray plume that rose 200 m above the crater. The Alert Level remained at 3 (on a scale of 1-4). During 1 May and at least into August, lava flows remained active. News indicated 600 people evacuated in August.

2012. Based on analyses of satellite imagery, the Darwin Volcanic Ash Advisory Centre (VAAC) reported that on 14 May 2012 an ash plume rose to 3.7 km a.s.l. and drifted 130 km SE. On 16 May an ash plume again rose to an altitude of 3.7 km a.s.l. then drifted about 110 km SE. The VAAC also described a 16 December ash plume to an altitude of 3.7 km drifting 110 km SE.

2013. Based on analyses of satellite imagery and wind data, the Darwin VAAC reported that on 9 April an ash plume rose to an altitude of 4.3 km a.s.l. and drifted over 45 km WNW. According to a (Kompas) news article, pahoehoe lava flows traveled 150 m and rock avalanches traveled 2 km on that same day.

Based on reports from the observation post in Salili, CVGHM stated on 26 July that the occurrence of rock avalanches descending Karangetang's flanks decreased during 2013; the last one occurred on 7 July, and traveled 2 km down the Batuawang and Kahetang (E) drainages. Although fog often prevented visual observations, white plumes were sometimes seen rising up to 500 m from two craters. Incandescence from the lava dome was reflected in the plume at night. Seismicity fluctuated, but signals indicating avalanches declined. Based on the cessation of avalanches, visual observations, and decreasing seismicity, the Alert Level was lowered to 2 (on a scale of 1-4) on 26 July.

Based on observations from the post in Salili, CVGHM reported that although Karangetang was sometimes covered in fog during 1 August-2 September white plumes were seen rising up to 500 m above the main crater and up to 300 m above Crater II. Incandescence from the crater was often observed at night. Avalanches began traveling down the Batuawang drainage on 2 September and then intensified the next day. The Alert Level was raised to 3 (on a scale of 1-4) on 3 September.

2014. Based on analyses of satellite imagery and wind data, the Darwin VAAC reported that on 9 February an ash plume rose to an altitude of 4.3 km a.s.l. and drifted over 80 km W.

MODVOLC thermal alerts. In BGVN 36:01 we reported thermal alerts derived from the Hawai'i Institute of Geophysics and Planetology Thermal Alerts System (MODVOLC), discussing the presence or absence of thermal alerts through the last available posted alert, 12 March 2011. During this report's duration, the alerts sometimes continued and were typically abundant, usually on the order of one or more per week or two, but in some cases several alerts per day, until pausing after 15 May 2011. They resumed during the days 8 and 13 August 2011 and then stopped.

When the alerts resumed on 17 May 2012, they had undergone a pause of 10 months. Alerts were again abundant during 17 May until 18 June 2012. A pause ensued until 9 September 2012 and the alerts were common until 26 January 2013. The subsequent pause ended and alerts resumed during 4 April-5 June 2013. The subsequent pause took place during 6 June-2 September 2013, and then the pause ended with a few alerts during 3-5 September 2013 but an absence of alerts for the remainder of 2013. When checked on 1 July 2014, only one alert for 2014 had been posted: 8 June 2014.

Information Contacts: Center of Volcanology and Geological Hazard Mitigation (CVGHM), Jalan Diponegoro 57, Bandung 40122, Indonesia (URL: http://portal.vsi.esdm.go.id/joomla/); Darwin Volcanic Ash Advisory Centre (VAAC), Bureau of Meteorology, Northern Territory Regional Office, PO Box 40050, Casuarina, NT 0811, Australia (URL: http://www.bom.gov.au/info/vaac/); Kompas (URL: http://nasional.kompas.com/read/2013/04/09/08311241/Guguran.Lava.Karangetang.Hingga.2.km ) and Hawai'i Institute of Geophysics and Planetology (HIGP) MODVOLC Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://hotspot.higp.hawaii.edu/).

Karangetang (Api Siau) volcano lies at the northern end of the island of Siau, north of Sulawesi. The 1784-m-high stratovolcano contains five summit craters along a N-S line. Karangetang is one of Indonesia's most active volcanoes, with more than 40 eruptions recorded since 1675 and many additional small eruptions that were not documented in the historical record (Catalog of Active Volcanoes of the World: Neumann van Padang, 1951). Twentieth-century eruptions have included frequent explosive activity sometimes accompanied by pyroclastic flows and lahars. Lava dome growth has occurred in the summit craters; collapse of lava flow fronts has also produced pyroclastic flows.

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

Start Date Stop Date Eruption Certainty VEI Evidence Activity Area or Unit
[ 2014 Jun 8 ] [ 2014 Jun 8 ] Uncertain    
2014 Feb 9 2014 Feb 9 Confirmed 1 Historical Observations
2012 May 17 2013 Sep 5 Confirmed 2 Historical Observations
2011 Mar 11 2011 Aug 13 Confirmed 2 Historical Observations
2010 Aug 6 2010 Dec (?) Confirmed 3 Historical Observations
2008 Nov 29 (?) 2010 Mar 24 (?) Confirmed 2 Historical Observations
[ 2008 Mar 12 ] [ Unknown ] Uncertain 1  
2006 Jul 3 2007 Oct (in or after) Confirmed 1 Historical Observations
2004 Apr 2 (?) 2005 Aug 5 (?) Confirmed 2 Historical Observations
1999 Mar (in or before) 2003 Oct 28 Confirmed 3 Historical Observations
1998 Jul 5 ± 4 days Unknown Confirmed 1 Historical Observations
1996 Oct 1 (in or before) 1997 Jun (in or after) Confirmed 1 Historical Observations
1995 Nov 9 1995 Dec 17 Confirmed 1 Historical Observations
1991 Jul 2 (in or before) 1993 Dec 31 (in or after) Confirmed 2 Historical Observations
1989 Jul 1989 Jul Confirmed 1 Historical Observations
1983 May 1988 Dec 31 (in or after) Confirmed 3 Historical Observations Summit and SW flank (1443 m)
1982 Unknown Confirmed 1 Historical Observations
1980 Mar 24 1980 Sep 13 Confirmed 1 Historical Observations
1979 May 31 1979 May 31 Confirmed 1 Historical Observations NNW flank, 1300 m (Kawah Maralebule)
1978 Feb 22 1978 Dec 18 Confirmed 1 Historical Observations
1976 Sep 15 1977 Sep Confirmed 2 Historical Observations South flank (1100 m) and summit
1972 Jan 1976 Apr 5 Confirmed 3 Historical Observations
1970 Nov 27 1971 Mar Confirmed 2 Historical Observations
1967 Nov 29 1967 Dec 2 Confirmed 2 Historical Observations
1965 Apr 5 ± 4 days 1967 Jun Confirmed 2 Historical Observations
1962 Jan 29 1963 Dec Confirmed 2 Historical Observations
1961 Oct 9 1961 Oct 19 (in or after) Confirmed 2 Historical Observations
1961 Feb 28 1961 Apr Confirmed 2 Historical Observations
1953 Unknown Confirmed 2 Historical Observations
1952 Feb 1952 Jun 30 Confirmed 2 Historical Observations Craters I, II and III
1949 Sep 14 Unknown Confirmed 2 Historical Observations
1948 Dec Unknown Confirmed 2 Historical Observations
1947 Dec 1 1947 Dec 21 Confirmed 2 Historical Observations
1947 Feb 9 1947 Feb 9 Confirmed 2 Historical Observations
1941 Oct 30 1941 Oct 30 Confirmed 2 Historical Observations
1940 Jun 20 1940 Aug 23 Confirmed 2 Historical Observations
1940 Mar 1 1940 Mar 9 Confirmed 2 Historical Observations
1935 Aug 31 Unknown Confirmed 2 Historical Observations
1930 Nov (?) Unknown Confirmed 2 Historical Observations
1930 Feb 4 1930 Feb 6 Confirmed 2 Historical Observations Crater IV
1926 Oct Unknown Confirmed 2 Historical Observations
1924 May Unknown Confirmed 2 Historical Observations
1922 May 4 1922 Dec 13 Confirmed 2 Historical Observations Crater IV
1921 Mar 1921 Jun (in or after) Confirmed 2 Historical Observations Crater V
1905 May 21 1905 May 22 Confirmed 2 Historical Observations
1900 Unknown Confirmed 2 Historical Observations
1899 Unknown Confirmed 2 Historical Observations
1892 Jun 14 (?) Unknown Confirmed 2 Historical Observations
1887 May 27 1887 May 27 Confirmed 2 Historical Observations
1886 Apr 25 1886 Jun 19 (in or after) Confirmed 2 Historical Observations Crater III
1883 Aug 25 1883 Aug 26 Confirmed 2 Historical Observations Crater II?
1864 Jun 6 Unknown Confirmed 2 Historical Observations
1825 Unknown Confirmed 2 Historical Observations
1712 Jan 16 Unknown Confirmed 2 Historical Observations
1675 Unknown Confirmed 3 Historical Observations

This compilation of synonyms and subsidiary features may not be comprehensive. Features are organized into four major categories: Cones, Craters, Domes, and Thermal Features. Synonyms of features appear indented below the primary name. In some cases additional feature type, elevation, or location details are provided.


Synonyms

Api Siau | Awoeh
Karangetang volcano, also known as Api Siau, is the northernmost of a chain of volcanoes forming the elongated island of Siau in the Sangihe arc. Seen here from Ulu village on the north, Karangetang is one of Indonesia's most active volcanoes, with more than 40 eruptions recorded since 1675.

Photo by Ruska Hadian, 1973 (Volcanological Survey of Indonesia).
Steam rises from a lava flow descending the north flank in 1976, viewed from Ulu village. A period of almost continuous eruptive activity that began in January 1972 ended in April 1976. Intermittent explosive eruptions were accompanied by lava dome growth and lava flows and lahars.

Photo by J. Matahelumual, 1976 (Volcanological Survey of Indonesia).
A blocky lava flow descends into a coconut grove during an eruption in 1976. This eruption, which lasted from July 1976 to September 1977, originated from a south-flank vent and produced a lava flow that traveled 7 km to the sea. The lava flow destroyed 24 houses and thousands of coconut and olive trees.

Photo by J. Matahelumual, 1976 (Volcanological Survey of Indonesia).
An eruption began on September 15, 1976, from a new vent on the south flank at 1000 m altitude. It produced a lava flow, seen in the foreground of this photo, that traveled 7 km to reach the sea on the SW flank. Pyroclastic flows from collapse of the lava flow's terminous scorched vegetation near the flow, destroyed houses, and caused one fatality. The eruption lasted until September of the following year.

Photo by J. Matahelumual, 1976 (Volcanological Survey of Indonesia).
A blocky lava flow, seen here from the NW, descends the southern flank of Karengetang (Api Siau) volcano in 1976. An eruption began on September 15 from a new vent on the south flank at 1000 m altitude. The lava flow traveled 7 km to reach the sea on the SW flank. Pyroclastic flows from collapse of the lava flow's terminous scorched vegetation near the flow, destroyed houses, and caused one fatality. Minor cauliflower-like gas emission accompanied by rumblings continued until the end of the eruption in September of the following year.

Photo by J. Matahelumual, 1976 (Volcanological Survey of Indonesia).
A time exposure captures a nighttime view from the south of explosive eruptions at the summit of Karangetang volcano in February 1985, part of an eruption that began in May 1983 and lasted until the end of 1988. On February 24, 1985, a new vent opened on the south flank, sending a lava flow down the Batuawang River.

Photo by S.R. Wittiri, 1985 (Volcanological Survey of Indonesia).
Karangetang (Api Siau) volcano rises above the Pengamatan Maralawa volcano observation post of the Volcanological Survey of Indonesia near the village of Salili on the southern flank. Karangetang is one of Indonesia's most active volcanoes. Twentieth-century eruptions have included frequent explosive activity that is sometimes accompanied by pyroclastic flows and lahars. Lava dome growth has occurred in the summit craters; collapse of lava flow fronts has also produced pyroclastic flows.

Photo by L. Manalu, 1986 (Volcanological Survey of Indonesia).
An eruption plume above the summit of Karengetang (Api Siau) volcano is seen from Ulu village on the northern flank sometime during 1961. Explosive eruptions in that year began on February 28 and lasted until April. Incandescent material was ejected to 300 m above the vent and the eruption plume rose 1.5 km above the crater. Explosive activity also occurred in October 1961.

Photo by M. Pantauw, 1961 (published in Kusumadinata 1979, "Data Dasar Gunungapi Indonesia").
Karangetang (Api Siau) is one of Indonesia's most active volcanoes. Twentieth-century eruptions have included frequent explosive activity that is sometimes accompanied by pyroclastic flows and lahars. Lava dome growth has occurred in the summit craters; collapse of lava flow fronts has also produced pyroclastic flows.

Photo by Volcanological Survey of Indonesia.
A night time view on August 28, 2007 shows incandescent ejecta from the summit crater and glowing rock avalanches down the flanks. Activity at the frequently active Karangetang volcano had resumed with a small eruption on July 3, 2006 that produced an ash plume. On July 12 lava flows were observed descending to the east, and a pyroclastic flow occurred on July 21. Lava flows were also reported in August, and intermittent explosive activity continued in 2007.

Photo by Iyan Mulyana, 2007 (Centre of Volcanology & Geological Hazard Mitigation, Volcanological Survey of Indonesia).

The following references have all been used during the compilation of data for this volcano, it is not a comprehensive bibliography. 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.

Manalu L, 1986. G Karangetang. Bull Volc Surv Indonesia, 109: 1-48.

Morrice M G, Jezek P A, Gill J B, Whitford D J, Monoarfa M, 1983. An introduction to the Sangihe arc: volcanism accompanying arc-arc collision in the Molucca Sea, Indonesia. J Volc Geotherm Res, 19: 135-165.

Neumann van Padang M, 1951. Indonesia. Catalog of Active Volcanoes of the World and Solfatara Fields, Rome: IAVCEI, 1: 1-271.

Sudradjat A, 1977. . (pers. comm.).

Volcanological Survey of Indonesia, 1986b. Annual report of the Volcanological Survey 1984-1985. Bull Volc Surv Indonesia, no 113.

Volcano Types

Stratovolcano

Tectonic Setting

Subduction zone
Oceanic crust (< 15 km)

Rock Types

Major
Andesite / Basaltic Andesite
Basalt / Picro-Basalt

Population

Within 5 km
Within 10 km
Within 30 km
Within 100 km
892
4,478
11,066
65,667

Affiliated Databases

Large Eruptions of Karangetang [Api Siau] Information about large Quaternary eruptions (VEI >= 4) is cataloged in the Large Magnitude Explosive Volcanic Eruptions (LaMEVE) database of the Volcano Global Risk Identification and Analysis Project (VOGRIPA).
WOVOdat WOVOdat is a database of volcanic unrest; instrumentally and visually recorded changes in seismicity, ground deformation, gas emission, and other parameters from their normal baselines. It is sponsored by the World Organization of Volcano Observatories (WOVO) and presently hosted at the Earth Observatory of Singapore.
EarthChem EarthChem develops and maintains databases, software, and services that support the preservation, discovery, access and analysis of geochemical data, and facilitate their integration with the broad array of other available earth science parameters. EarthChem is operated by a joint team of disciplinary scientists, data scientists, data managers and information technology developers who are part of the NSF-funded data facility Integrated Earth Data Applications (IEDA). IEDA is a collaborative effort of EarthChem and the Marine Geoscience Data System (MGDS).
Smithsonian Collections Search the Smithsonian's NMNH Department of Mineral Sciences collections database. Go to the "Search Rocks and Ores" tab and use the Volcano Name drop-down to find samples.