Kirishimayama

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  • 31.934°N
  • 130.862°E

  • 1700 m
    5576 ft

  • 282090
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Most Recent Weekly Report: 23 October-29 October 2013


On 22 October the JMA reported that no eruptions had been detected at Shinmoe-dake (Shinmoe peak), a stratovolcano of the Kirishima volcano group, since the eruption on 7 September 2011. Earthquake activity and sulfur dioxide emissions were both below the detection limit. The Alert Level was lowered to 2 (on a scale of 1-5).

Source: Japan Meteorological Agency (JMA)


Most Recent Bulletin Report: July 2012 (BGVN 37:07)


Gradual decline in activity following explosive 2011 eruptions

The early 2011 eruption of Shinmoe-dake (Shinmoedake) volcano of the Kirishima Volcanic Group was characterized by sub-Plinian and Vulcanian explosions and an ~600-m-diameter lava dome that was extruded into the crater (BGVN 35:12 and 36:07, reports covering through July 2011). Fewer eruptions occurred during an ensuing decline in activity, where plumes only rose to up to 1 km above the summit. No explosions (defined as accompanying an air shock larger than 20 Pa and explosive earthquake signals) were reported by the Japan Meteorological Agency (JMA) after 11 May 2011 and through June 2012. This report discusses diminishing plume emissions and seismicity during September 2011-June 2012, and supplies more context on the entire eruptive episode. The material in this report is based on JMA monthly reports, which are now available in English with coverage starting in October 2010.

2011 eruption wanes. After the explosive eruptions during January-February 2011, eruptions (ash emissions) at Shinmoe-dake occurred through 7 September 2011. After that, JMA reported no further eruptions at least through June 2012; gas-and-steam plumes rose to a maximum of ~600 m above the crater of Shinmoe-dake after 7 September 2011 (figure (18).

Figure 18. Plume behavior and seismicity at Kirishima during intervals bracketing the explosive activity of January-May 2011. The inset plot shows daily maximum plume heights (black bars, in meters above the summit) and eruptions (red arrows) since 2008, with the yellow shaded area indicating the temporal coverage of the main plot. The main plot shows maximum plume heights per month (kilometers above sea level, km a.s.l., right axis, where gray bars indicate months in which plumes contained ash, and white bars indicate months in which ash was absent in all plumes) and seismicity (seismic events per month, black line, left axis). Coverage of previous Bulletin reports is indicated at the top of the plot. Data and inset plot courtesy of JMA.

Elevated seismicity continued following the cease of explosive eruptions in May 2011, but a substantial protracted decline too place during August-November 2011. In May and June 2012, JMA reported that seismicity had returned to background levels seen prior to the onset of the early 2011 explosive activity, and they reported an absence of measured tremor over the same two months (figures 18 and 19).

Figure 19. Kirishima’s daily high-frequency (H-F) earthquake counts plotted with tilt measurements (E-W component shown in blue, N-S component shown in red), indications of tremor (black x’s, top), ash eruptions (gray volcano symbols) and explosions (red volcano symbols) during January 2011-June 2012 at Shinmoe-dake. The black arrow indicates a tilt change of 4 microradians (µrad); the blue (E-W) and red (N-S) triangles indicate the start and end points of the tilt component records. Courtesy of JMA.

JMA reported that GPS baseline extension indicated “magma supply to a deeper chamber several kilometers northwest of the crater” through December 2011; the baseline extension slowed after December. JMA initially reported almost no change after January 2012, but during June 2012 the baseline distance between Ebino (~16 km NNW) and Makizono (~14 km WSW) shortened.

Observation flights conducted through various collaborations between the Japan Ground, Air, and Maritime Self-Defense Forces (JGSDF, JASDF, and JMSDF, respectively) and the Ministry of Land, Infrastructure, Transportation and Tourism (MLIT) allowed frequent aerial photography and infrared thermal measurements of the crater and edifice of Shinmoe-dake. The diameter of the lava dome within the crater remained ~600 m as of June 2012 (indicating little-to-no growth since 30 January 2011). Infrared thermal photography revealed little thermal structure to the dome, but highlighted comparatively high-temperature areas at its margins. A fissure (described as a “crack” by JMA) located on the W slope of the edifice was occasionally reported to emit plumes, and exhibited an elevated temperature compared with the rest of the edifice (figure 20). Similar aerial and thermal observations were reported as late as 10 May 2012.

Figure 20. Aerial photograph (top) and infrared thermal image (bottom) of the summit of Shinomoe-dake volcano on 21 February 2012, illustrating a high-temperature anomaly that occurred within a fissure (described as a “crack” by JMA) on the W slope, where plumes were occasionally observed (labeled with ‘*’). For orientation, the same symbol is placed just S of the same approximate location in the aerial photo (top). Courtesy of JMSDF, MLIT, and JMA.

The Alert Level remained at 3 (on a scale from 1-5) at the end of June 2012.

Information Contacts: Japan Meteorological Agency (JMA), Otemachi, 1-3-4, Chiyoda-ku Tokyo 100-8122, Japan (URL: http://www.jma.go.jp/jma/indexe.html); Japan Ground Self-Defense Force (JGSDF) (URL: http://www.mod.go.jp/gsdf/english/index.html); Japan Air Self-Defense Force (JASDF) (URL: http://www.mod.go.jp/asdf/English_page/organization/formation01/); Japan Maritime Self-Defense Force (JMSDF) (URL: http://www.mod.go.jp/msdf/formal/english/index.html); Ministry of Land, Infrastructure, Transportation and Tourism (MLIT) (URL: http://www.mlit.go.jp/en/index.html).

Index of Weekly Reports


2013: October
2011: January | February | March | April | June | August
2010: March | May | June | July
2008: August
2004: January

Weekly Reports


23 October-29 October 2013

On 22 October the JMA reported that no eruptions had been detected at Shinmoe-dake (Shinmoe peak), a stratovolcano of the Kirishima volcano group, since the eruption on 7 September 2011. Earthquake activity and sulfur dioxide emissions were both below the detection limit. The Alert Level was lowered to 2 (on a scale of 1-5).

Source: Japan Meteorological Agency (JMA)


31 August-6 September 2011

Based on notifications from JMA, the Tokyo VAAC reported that during 31 August-6 September ash plumes from Kirishima's Shinmoe-dake (Shinmoe peak) rose to altitudes of 1.5-2.1 km (5,000-7,000 ft) a.s.l. and drifted N, S, and SW.

Source: Tokyo Volcanic Ash Advisory Center (VAAC)


3 August-9 August 2011

Based on notifications from JMA, the Tokyo VAAC reported an eruption from Kirishima on 6 August.

Source: Tokyo Volcanic Ash Advisory Center (VAAC)


29 June-5 July 2011

Based on notifications from JMA, the Tokyo VAAC reported that on 29 June an eruption from Kirishima's Shinmoe-dake (Shinmoe peak) produced a plume that rose to altitudes of 1.8-2.4 km (6,000-8,000 ft) a.s.l. and drifted N.

Source: Tokyo Volcanic Ash Advisory Center (VAAC)


22 June-28 June 2011

Based on notifications from JMA, the Tokyo VAAC reported that on 23 June an eruption from Kirishima's Shinmoe-dake (Shinmoe peak) produced a plume that rose to an altitude of 1.8 km (6,000 ft) a.s.l. and drifted E.

Source: Tokyo Volcanic Ash Advisory Center (VAAC)


13 April-19 April 2011

Based on notifications from JMA, the Tokyo VAAC reported that on 18 April an ash plume from Kirishima's Shinmoe-dake (Shinmoe peak) rose to an altitude of 3.7 km (12,000 ft) a.s.l. and drifted SE.

Source: Tokyo Volcanic Ash Advisory Center (VAAC)


30 March-5 April 2011

Based on notifications from JMA and pilot observations, the Tokyo VAAC reported that during 3-4 April ash plumes from Kirishima's Shinmoe-dake (Shinmoe peak) rose to altitudes of 4.6-6.1 km (15,000-20,000 ft) a.s.l. and drifted E.

Source: Tokyo Volcanic Ash Advisory Center (VAAC)


23 March-29 March 2011

Based on notifications from JMA, the Tokyo VAAC reported that an eruption from Kirishima's Shinmoe-dake (Shinmoe peak) on 23 March produced a plume that rose to an altitude of 2.4 km (8,000 ft) a.s.l. and drifted SE. Subsequent notices that day stated that the ash had dissipated. An eruption on 29 March produced a plume that rose to an altitude of 2.1 km (7,000 ft) a.s.l. and drifted SE.

Source: Tokyo Volcanic Ash Advisory Center (VAAC)


9 March-15 March 2011

Based on notifications from JMA and pilot observations, the Tokyo VAAC reported that an eruption from Kirishima's Shinmoe-dake (Shinmoe peak) on 13 March produced ash plumes that rose to altitudes of 5.5-6.1 km (18,000-20,000 ft) a.s.l. Some plumes drifted E. According to news sources, people within 1.6 km evacuated and windows more than 6 km away shattered.

Sources: Tokyo Volcanic Ash Advisory Center (VAAC); Daily Mail


2 March-8 March 2011

The Tokyo VAAC reported that an ash plume from Kirishima's Shinmoe-dake (Shinmoe peak) observed by a pilot on 3 March rose to an altitude of 3.7 km (12,000 ft) a.s.l. and drifted NE. Based on reports from JMA, the Tokyo VAAC reported that plumes rose to altitudes of 1.5-3 km (5,000-10,000 ft) a.s.l. and drifted SE during 3-4 and 8 March.

Source: Tokyo Volcanic Ash Advisory Center (VAAC)


23 February-1 March 2011

Based on reports from JMA, the Tokyo VAAC reported that eruptions from Kirishima's Shinmoe-dake (Shinmoe peak) on 24 and 28 February as well as 1 March produced plumes that rose to altitudes of 1.8-2.1 km (6,000-7,000 ft) a.s.l. and drifted N, E, and SE.

Source: Tokyo Volcanic Ash Advisory Center (VAAC)


16 February-22 February 2011

Based on reports from JMA, the Tokyo VAAC reported that on 18 February an explosion from Shinmoe-dake (Shinmoe peak), a stratovolcano of the Kirishima volcano group, produced a plume that rose to an altitude of 4.6 km (15,000 ft) a.s.l. and drifted S. A pilot reported that an ash plume rose to an altitude of 5.5 km (18,000 ft) a.s.l. and drifted E. The next day, satellite imagery showed that the ash had dissipated.

According to a news article on 17 February, officials recommended that more than 2,500 residents should evacuate their homes due to potential lahar activity from heavy rain. An official noted that 63 people in Miyakonojo (30 km SE) had already moved to evacuation shelters.

Sources: Tokyo Volcanic Ash Advisory Center (VAAC); Stuff


9 February-15 February 2011

Based on reports from JMA, the Tokyo VAAC reported that during 9-11 February explosions from Shinmoe-dake (Shinmoe peak), a stratovolcano of the Kirishima volcano group, produced plumes that rose to altitudes of 1.8-4 km (6,000-13,000 ft) a.s.l. and drifted E and SE. On 11 and 14 February, pilots observed ash plumes that rose to altitudes of 4.6-6.1 km (15,000-20,000 ft) a.s.l. According to a news article, rocks ejected during an eruption on 14 February broke windows in cars parked at the Kirishima service area on the Miyazaki expressway and in several places in Kobayashi, 13 km NE.

Sources: Tokyo Volcanic Ash Advisory Center (VAAC); Japan Today


2 February-8 February 2011

According to a news article, explosions on 2 February from Shinmoe-dake (Shinmoe peak), a stratovolcano of the Kirishima volcano group, disrupted flights to Tokyo. The article also noted that JMA widened the restricted zone to a 4-km-radius around the crater. About 600 people from Miyazaki (55 km E) had evacuated.

Based on reports from JMA, analyses of satellite imagery, and pilot observations, the Tokyo VAAC reported that during 2-8 February ash plumes rose to altitudes of 1.5-4.6 km (5,000-15,000 ft) a.s.l. and drifted SE. On 3 February, a pilot noted that an ash plume rose to an altitude of 9.1 km (30,000 ft) a.s.l. and drifted NE.

According to JMA, scientists observed Shinmoe-dake during an overflight on 6 February and noted that the lava dome was about 600 m in diameter, similar to observations from four days prior. Gas plumes rose from the edges of the lava dome, from multiple areas on the E side of the dome, and from a central vent. Ash plumes rose 1.5 km above the crater rim and drifted SE.

Sources: Volcano Research Center-Earthquake Research Institute (University of Tokyo); Japan Meteorological Agency (JMA); Tokyo Volcanic Ash Advisory Center (VAAC); Asia One


26 January-1 February 2011

According to the Earthquake Research Institute, an explosion on 26 January from Shinmoe-dake (Shinmoe peak), a stratovolcano of the Kirishima volcano group, prompted JMA to raise the Alert Level to 3 (on a scale of 1-5). Lightning in the ash plume was visible in video footage that same day. Based on reports from JMA, analyses of satellite imagery, and pilot observations, the Tokyo VAAC reported that during 26-27 January ash plumes rose to altitudes of 1.8-2.1 km (6,000-7,000 ft) a.s.l. and drifted SE. According to news articles, tephra fell as far away as 8 km on 27 January and disrupted airline and train services. Some people in Miyazaki (55 km E) voluntarily evacuated and approximately 30 people in Takaharu (15 km E) spent the night in an evacuation center. Video footage showed people clearing ash from the streets.

During an overflight on 29 January, scientists observed a new lava dome in the crater, about 50 m in diameter and incandescent in some areas. They also observed that the crater lake was gone and pyroclastic-flow deposits, 500-600 m long, were present in the SW crater. Notices issued from the Tokyo VAAC during 28-30 January stated that ash emissions were continuing. On 31 January, an ash plume rose to an altitude of 2.1 km (7,000 ft) a.s.l. and drifted SE. A news article noted that an explosion on 1 February was heard more than 7 km away, and broke glass in buildings and cars as far as 8 km away.

Sources: Volcano Research Center-Earthquake Research Institute (University of Tokyo); Tokyo Volcanic Ash Advisory Center (VAAC); Japan Today; Agence France-Presse (AFP); BBC News


19 January-25 January 2011

According to JMA, an eruption from Shinmoe-dake (Shinmoe peak), a stratovolcano of the Kirishima volcano group, on 19 January produced a shock wave that was detected 12 km NE and an ash plume that drifted SE. Ashfall up to 5 mm thick was reported in Miyakonojo (30 km SE); ashfall was also reported as far as Nichinan City (60 km SE). An eruption on 22 January ejected material 200 m above the vent. Based on reports from JMA and pilot observations, the Tokyo VAAC reported that ash plumes rose to altitudes of 1.8-2.1 km (6,000-7,000 ft) a.s.l. and drifted SE.

Sources: Japan Meteorological Agency (JMA); Tokyo Volcanic Ash Advisory Center (VAAC)


7 July-13 July 2010

Based on reports from JMA, the Tokyo VAAC reported that an eruption from the Kirishima volcanic complex on 10 July produced a plume that rose to an altitude of 1.8 km (6,000 ft) a.s.l.

Source: Tokyo Volcanic Ash Advisory Center (VAAC)


23 June-29 June 2010

Based on reports from JMA, the Tokyo VAAC reported a possible eruption of Kirishima on 28 June. Information about a possible resulting plume was not reported.

Source: Tokyo Volcanic Ash Advisory Center (VAAC)


26 May-1 June 2010

According to JMA, a small eruption from Shinmoe-dake (Shinmoe peak), a stratovolcano of the Kirishima volcano group, on 27 May produced an ash plume that rose 100 m above the crater rim. Ashfall was noted in areas within 6 km. Emissions gradually decreased.

Source: Japan Meteorological Agency (JMA)


31 March-6 April 2010

An eruption from Shinmoe-dake (Shinmoe peak), a stratovolcano of the Kirishima volcano group, on 30 March prompted JMA to raise the Alert Level from 1 to 2 (on a scale of 1-5). Ash blanketed the ground to the W of the crater.

Source: Japan Meteorological Agency (JMA)


20 August-26 August 2008

Based on reports from JMA, the Tokyo VAAC reported a possible eruption of Kirishima on 22 August. The altitude and direction of a possible resultant plume were not reported.

Source: Tokyo Volcanic Ash Advisory Center (VAAC)


14 January-20 January 2004

Seismicity increased from "normal" levels at Kirishima on 13 December, and the same day Dr. Kobayashi of Kagoshima University found new fumarole pits at the volcano's Ohachi Crater. A video camera at the volcano showed steam rising above the crater rim. Observers saw two new pits that formed in the middle of the crater's southern inner wall and steam rising to ~100 m. Also, pebbles (that were 2-3 cm across) and mud were scattered within about 10 m of these pits. JMA issued a volcanic advisory on 16 December, as the possibility of a small eruption had increased, judging from the high level of seismic and thermal activity. On 17 December authorities announced that tourists were not permitted to visit Ohachi Crater. The level of seismicity peaked in mid December, then declined somewhat, continuing at a relatively high level through at least mid January.

Source: Volcano Research Center-Earthquake Research Institute (University of Tokyo)


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.

09/1978 (SEAN 03:09) Earthquake swarm 7 July

06/1979 (SEAN 04:06) Small sulfur flow ejected last winter

03/1981 (SEAN 06:03) New fumaroles in residential area

01/1982 (SEAN 07:01) Sulfur flow; fumarole temperature increase

11/1991 (BGVN 16:11) Increased seismicity; gas emission

12/1991 (BGVN 16:12) Continued steaming and weak tremor

01/1992 (BGVN 17:01) Slight ash emission; seismicity declines

02/1992 (BGVN 17:02) Steam emission; fine ashfall near vents; tremor ends

03/1992 (BGVN 17:03) Steam emission and weak seismicity

04/1992 (BGVN 17:04) Steam emission; minor ashfall

08/1995 (BGVN 20:08) Seismicity increased in late August

09/1995 (BGVN 20:09) Seismicity decreases near Shinmoe Crater

02/2000 (BGVN 25:02) Earthquake swarm during 6-15 November 1999

09/2008 (BGVN 33:09) 22 August 2008 eruption sent ash 25 km from fissure vents at Shinmoe-dake

12/2010 (BGVN 35:12) Large eruption of Shinmoe-dake begins in January 2011

07/2011 (BGVN 36:07) February 2011 explosions launching ballistics; evacuations

07/2012 (BGVN 37:07) Gradual decline in activity following explosive 2011 eruptions




Bulletin Reports

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


09/1978 (SEAN 03:09) Earthquake swarm 7 July

An earthquake swarm in the vicinity of Kirishima, including some felt events, was recorded on 7 July. No surface activity was observed. Kirishima's last eruption, on 5 August 1971, ejected accessory tephra and mud. No seismicity was recorded preceding the 1971 eruption.

Further Reference. Ida, Y., Yamaguchi, M, and Masutani, F., 1986, Recent seismicity and stress field in Kirishima volcano: Journal of the Seismological Society of Japan, v. 39, p. 111-121.

Information Contacts: Japan Meteorological Agency (JMA); D. Shackelford, CA.

06/1979 (SEAN 04:06) Small sulfur flow ejected last winter

JMA personnel visited the summit crater of Shinmoe-dake, one of the SE group of volcanic edifices in the Kirishima complex, on 23 April. They found a 10-cm-wide sulfur flow that had traveled more than 50 m downslope from one of the summit crater fumaroles, which also was surrounded by scattered, explosively ejected sulfur. The sulfur, molten when it was ejected during the winter, was a dark brown solid in April.

Information Contacts: JMA.

03/1981 (SEAN 06:03) New fumaroles in residential area

Fumarolic activity had increased since November 1980 in the Iodani ("Sulfur Valley") area at the W base of the volcano. Personnel from Kagoshima and Tokyo Universities, Tokyo Industrial College, and the JMA observatory monitored the temperatures and the chemical composition of the vapor. The highest temperature measured was 98°C in March, the same as during the past 2 years. The gas content varied from 90% CO2-10% H2S to 70% CO2-30% H2S. New fumaroles appeared in a residential area. Because of the dense gas, civil police closed a parking area and part of a road.

Information Contacts: JMA.

01/1982 (SEAN 07:01) Sulfur flow; fumarole temperature increase

On 8 January JMA personnel discovered a 6-m-long, 30-cm-wide, 2-cm-thick sulfur flow that had emerged from Fumarole No. 6 in Shinmoe-dake (figure 1), a crater in the summit area of the Kirishima volcanic complex. Pieces of sulfur and tar-like material were scattered around the fumarole.

Figure 1. Cross-section and map of Shinmoe-dake crater at Kirishima. Numbers identify individual fumaroles. Courtesy of JMA.

Increased geothermal activity was observed on the inner wall of Shinmoedake in December. The measured temperature of Fumarole No. 6 was 184°C, the highest since JMA's Kagoshima Observatory began summit area temperature measurements in 1979. Vegetation on the N inner wall had been damaged by the increased activity. Fumarolic activity in the Iodani area, about 5 km WSW of Shinmoedake, had increased from November 1980 through 1981. On 8 January JMA observers found that this activity had declined to its usual level. The last major activity at Shinmoedake was a steam explosion in 1959, when tephra was ejected, mainly from the fissure trending W from the crater.

Information Contacts: JMA.

11/1991 (BGVN 16:11) Increased seismicity; gas emission

A swarm of microearthquakes began at around 2300 on 13 November beneath Shinmoe-dake cone. The number of earthquakes increased sharply the next day, and seismicity remained elevated until the morning of 26 November, with the exception of two brief quiet periods on 19-20 and 23-24 November (figure 2). Seismicity reached the highest level since the start of monitoring in 1965 (figure 3), while episodic and continuous volcanic tremor were recorded for the first time. Five volcanic tremor episodes were recorded 13-23 November, ranging from 0.2 to 2.5 µm in amplitude and 1-7 minutes in duration. Continuous weak volcanic tremor (0.1 µm amplitude) began at 0305 on 26 November.

Figure 2. Daily number of earthquakes at Kirishima, 1 March-15 December 1991. Courtesy of JMA.
Figure 3. Monthly number of earthquakes at Kirishima, January 1970-November 1991. Courtesy of JMA.

Steam emission was first reported by tourists on 24 November, and confirmed during an overflight the following day. The plume rose 200-500 m from fumaroles on the E inner wall of the main crater; previous steam emission, last observed in 1990, had usually reached only a few meters high. Tremor and steam emissions continued as of 16 December.

Information Contacts: JMA.

12/1991 (BGVN 16:12) Continued steaming and weak tremor

Seismicity remained at low levels through mid-January, but weak tremor continued to be recorded by a seismometer 1.7 km SW of the summit crater. Steam began to emerge from the crater on 24 November, and steady steam emission to 100-200 m height was continuing in mid-January.

Information Contacts: JMA.

01/1992 (BGVN 17:01) Slight ash emission; seismicity declines

Steam emission . . . continued in January reaching 200-400 m height. Fieldwork 28-29 January revealed a trace of ash covering half of the crater floor, but no associated changes in seismicity were recorded. The monthly number of earthquakes declined to 38 in January, from 86 in December. Weak tremor was recorded continuously by seismometers near the cone, from late November through early February.

Information Contacts: JMA.

02/1992 (BGVN 17:02) Steam emission; fine ashfall near vents; tremor ends

Steam emission . . . continued steadily in February, reaching 200-300 m height. The ground around the fumaroles was covered by a fine dusting of ash during air reconnaissance on 5, 12, and 18 February. Seismicity was low, with continuous volcanic tremor ceasing on 2 February, and a monthly total of 25 recorded earthquakes . . . .

Information Contacts: JMA.

03/1992 (BGVN 17:03) Steam emission and weak seismicity

Steam emission from Shinmoe-dake cone's summit crater . . . produced a continuous 100-200-m-high plume in March. Seismicity was at low levels, with a monthly total of 27 small earthquakes, similar to February . . . . Two weak tremor episodes were recorded on 6 and 17 March. Fine ash emissions . . . were not observed in March.

Information Contacts: JMA.

04/1992 (BGVN 17:04) Steam emission; minor ashfall

Steam emission continued steadily in April to 100-200 m height. A light dusting of ash was noted on leaves in the crater during a 6 April visit. The maximum measured fumarole temperature was 96°C. Seismicity was at low levels in April, but a weak tremor episode was recorded on the 11th. A monthly total of 23 small earthquakes was recorded, almost unchanged from March. Similar activity continued through early May.

Information Contacts: JMA.

08/1995 (BGVN 20:08) Seismicity increased in late August

During 25-30 August there was an increase in seismicity near Shinmoe-dake; 126 earthquakes on the 26th were recorded 1.7 km SW. The maximum seismic amplitude of 3.2 µm occurred on the 30th. In total, 463 events were recorded in August.

Information Contacts: JMA.

09/1995 (BGVN 20:09) Seismicity decreases near Shinmoe Crater

The total number of earthquakes in September was 182, a significant decreased compared to the 463 recorded in August. On 29 September there were 25 earthquakes recorded at Station A, 1.7 km SW of Shinmoe-dake Crater, the highest daily total of the month.

Information Contacts: Volcanological Division, Seismological and Volcanological Department, Japan Meteorological Agency (JMA), 1-3-4 Ote-machi, Chiyoda-ku, Tokyo 100 Japan.

02/2000 (BGVN 25:02) Earthquake swarm during 6-15 November 1999

A Volcanic Advisory on Kirishima volcano (figure 4) was issued on 10 November 1999 by the Japan Meteorological Agency (JMA) after seismicity began increasing on 6 November. This is the first advisory at Kirishima since 27 August 1995 (BGVN 20:08 and 20:09). Earthquakes detected at a site 1.7 km SW of Shinmoe-dake totaled 666 during 6-15 November (table 1), peaking at 192 events on the 10th. No volcanic tremor was observed.

Figure 4. Steam from Shinmoe-dake at Kirishima looking towards the SE in 1991. Naka-dake is the adjacent cone with a flat top, and in the background is Ohachi (crater to the right), Takachiho-no-mine (the highest peak in the center), and Futatsuishi (left). Courtesy of T. Kagiyama, ERI.

Table 1. Daily numbers of volcanic earthquake events at Kirishima, 5-15 November 1999. Courtesy of JMA.

        1999       Volcanic Earthquakes

    05 November             0
    06 November            12
    07 November            16
    08 November            40
    09 November            81
    10 November           192
    11 November           128
    12 November            69
    13 November            86

Information Contacts: JMA-Fukuoka, Japan Meteorological Agency (JMA), 1-3-4 Ote-machi, Chiyoda-ku, Tokyo 100, Japan (Email: jma16@poplar.ocn.ne.jp); Setsuya Nakada and Tsuneomi Kagiyama, Volcano Research Center, Earthquake Research Institute, University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113, Japan (Email: nakada@eri.u-tokyo.ac.jp, kagiyama@eri.u-tokyo.ac.jp, URL: http://hakone.eri.u-tokyo.ac.jp/vrc/VRC.html, http://hakone.eri.u-tokyo.ac.jp/vrc/kagiyama/).

09/2008 (BGVN 33:09) 22 August 2008 eruption sent ash 25 km from fissure vents at Shinmoe-dake

In 1991 there was a seismic increase at Kirishima (BGVN 25:02), a group of more than 20 Quaternary volcanoes occupying 600 km2 in an area N of Kyushu island's Kagoshima Bay (figures 5 and 6). The previous eruption of Kirishima took place from 1 December 1991 to 19 April 1992, when Shinmoe-dake intermittently ejected ash (BGVN 16:11-17:04; Imura, 1992).

Figure 5. Wide-angle view of Shinmoe-dake crater at Kirishima looking NW. Prominent are both the crater wall and the aqua-blue lake. The flat-topped cone in the background is Karakuni-dake (summit elevation 1,700 m) the tallest peak in the Kirishima complex. The rubbly material draping the the lower half of the crater wall represents remnants of a lava lake formed during the 1716-17 eruption. Copyrighted photo by Keizo Morita (used with permission).
Figure 6. Maps of the South Kyushu region showing recently active volcanoes. The Kirishima volcanic group ("Kirishimayama") lies near the map's N edge. Taken from Matsumoto and others (2007).

This report notes that seismic and thermal unrest also occurred in 2003-2004. Four years later (in August 2008) Kirishma had a sudden, short-lived eruption. Although the plume seemingly did not rise above 1 km altitude, observers chronicled a thin airfall ash deposit highly elongate to the NE.

Late 2003 and early 2004 unrest. Seismicity increased from "normal" levels on 13 December 2003, and the same day observers saw new fumarole pits at the Ohachi crater. A video camera showed steam rising above that crater's rim. Observers saw two new pits that formed in the middle of that crater's southern inner wall and steam rising to ~ 100 m. Within ~ 10 m of these pits, observers saw freshly ejected mud and cognate pebbles 2-3 cm across. The seismicity peaked in mid-December, then declined somewhat, continuing at a relatively high level through at least mid-January 2004.

Multi-year seismic overview. Seismicity rose substantially starting on 19 August 2008 (figure 7), several days prior to the 22 August eruption. Japan Meteorological Agency (JMA) reported 1,005 earthquakes during August 2008. In contrast, the monthly number of earthquakes recorded during the previous 13 months ranged between 2 and 118, with only four earthquakes seen during each of the two months prior to the eruption.

Figure 7. Earthquakes and tremor duration measured at station A (1.7 km SW of the Shimoe-dake's summit) during 2003 to end of August 2008. The top two panels show daily earthquakes. The third panel down shows tremor, with circle size scaled to duration. The lowermost panel shows plume height, which was absent until the 22 August 2008 eruption. Taken from JMA (2008).

Tremor was rare during 2003-2008. There had been tremor during early 2006, and briefly in 2007, but the 2008 tremor included three episodes. During 2008 the longest tremor episode, in August, continued for 350 minutes (the full circle goes off the scale of the plot).

Eruption on 22 August 2008. The eruption began at 1634 on 22 August 2008 from Shinmoe-dake, a stratovolcano with a summit rim around 1,400 m elevation and a main 750-m-diameter crater containing a lake (figure 8). JMA noted that the tallest plume only reached ~ 850 m altitude. Post-eruption inspection found that fissures at Shinmoe-dake had recently opened both in the crater and on its W flank (figures 8 and 9). Also, observers found abundant ballistic lithics near the fissures.

Figure 8. Diagram showing key surface features found at Kirishima's Shinmoe-dake associated with the 22 August 2008 eruption. Also labeled is the upper margin of a lava lake that formed in the crater during the 1716-1717 eruption. Adapted from the August 2008 monthly report by Japan Meteorological Agency (JMA, 2008).
Figure 9. Aerial photo of the W flank of Shinmoe-dake at Kirishima showing fissures as seen on 24 August 2008. Some of these features were present prior to the eruption. An enlarged view shows numerous light colored ballistic blocks thrown out by the 2008 eruption. Some are apparently over a meter in diameter. Photo taken from JMA (2008).

Ash fell at Kobayashi City (10 km NE) and reached up to 25 km from the source (figure 10). According to Nobuo Geshi (Geological Survey of Japan), ~ 200,000 metric tons of ash was erupted. Under the microscope, the ash was composed mostly of non-juvenile materials, although some juvenile glass fragments were found (University of Tokyo - Earthquake Research Institute and Kagoshima University, 2008). As of early November 2008, authorities had not issued further reports, implying quiet conditions. Because of low seismicity and lack of ash plumes, JMA lowered the Alert Level from 2 to 1 on 29 October 2008.

Figure 10. Preliminary near-source isopach map describing ash fall from Kirishima's 22 August 2008 eruption. The map extends out to ~ 10 km from the vent (horizontal scale, bottom right) although ash also fell much farther away. On the key and enlarged views of this map one can see the sites where ash thickness data were collected, providing insight into the map's construction. Some of these points indicate the absence of detectible ash, and at two sites, density data. Field work supporting the map was conducted during 1-2 September 2008. Map was created by Nobuo Geshi (Geological Survey of Japan; original in Japanese).

Partial list of resources discussing Shinmoe-dake. Two informative reports in Japanese helped describe the eruption. The first was the report by JMA (2008), from which figures 7-9 were extracted. That report discussed pre- and post-eruption monitoring, including geophysics, geodetics, behavior of fumaroles, the development of new fissures and fumaroles (including photos and thermal anamalies). The second report, University of Tokyo - Earthquake Research Institute and Kagoshima University (2008), discussed erupted ash.

Fukui and others (2008) discussed Shinmoe-dake's deformation. Their studies employed deformation monitoring by Global Positioning System (GPS) during 2001-2007. Their data disclosed uplift starting in mid-2004.

A website mentioned Kirishima in regard to engineering approaches (sabo dams and related structures) to manage rivers and basins confronting mass wasting at volcanoes (Sakurajima International Sabo Center, 2008). The same site also shows a monitoring camera for Shimnoe-dake and posts a disaster prevention map for Kirishima (in Japanese).

In 1992, geophysicists completed a self-potential survey at Shinmoe-dake (Hashimoto and others, 1994) finding a negative anomaly over the crater basin, a result interpreted as due to streaming potential due to the crater lake and the motion of ions through porous rock. Positive anomalies were small and local and corresponded to fumaroles. Continuous self-potential monitoring during December 1991 to 1993 indicated few changes.

References. Fukui, K., Torisu, K., Tomoyuki, K., Sakai, T., and Takagi, A., 2008, Volcano deformation detected by GPS observation around Shinmoe-dake crater of Kirishima and pressure source estimation by FEM: Meeting Proceedings of the Japan Geoscience Union, Makuhari, Japan, 26 May 2008, v. 151, p. 20.

Imura, R., 1992, Minor phreatic activity of Shinmoedake, Kirishima volcano, in 1991-92: Bull Volc Soc Japan (Kazan), v. 37, p. 281-283 (in Japanese).

Hashimoto, T., Kagiyama, T., and Masutani, F., Self-potential measurements on Shinmoe-Dake, Kirishima Volcanic Group: Bull. Earthq. Res. Inst. Univ. of Tokyo, v. 69, p. 257-266.

Japan Meteorological Agency, 2008, August 2008 Monthly Report on Kirishima: Japan Meteorological Agency (URL: http://www.seisvol.kishou.go.jp/tokyo/STOCK/monthly_v-act_doc/fukuoka/08m08/505_08m08.pdf).

Matsumoto, T., Ueno, H., and Kobayashi, T., 2007, A new secular variation curve for South Kyushu, Japan, and its application to the dating of some lava flows: Rep. Fac. Sci., Kagoshima Univ., no. 40, p. 35-49.

University of Tokyo - Earthquake Research Institute and Kagoshima University, 2008, About ejecta of eruption of 22 August 2008 from Shinmoe-dake (Kirishima): University of Tokyo (Earthquake Research Institute) and Kagoshima University (in Japanese; published 30 August 2008) (URL: www.eri.u-tokyo.ac.jp/topics/Kirishima2008/Figure/kazanbai080830.pdf).

Sakurajima International Sabo Center, 2008, Volcanic Sabo in Japan: Sakurajima International Sabo Center (URL: http://www.qsr.mlit.go.jp/osumi/sivsc/home/english/j038.html).

Information Contacts: Volcanological Division, Seismological and Volcanological Department, Japan Meteorological Agency (JMA), 1-3-4 Ote-machi, Chiyoda-ku, Tokyo 100 Japan; Nobuo Geshi, Geological Survey of Japan (GSJ), AIST, (Volcanic activity research group), Building No. 7, 1-1-1 Higashi, Tsukuba, Ibaraki, 305-8567 Japan (Email: geshi-nob@aist.go.jp); Volcano Research Center (VRC-ERI), Earthquake Research Institute, University of Tokyo , Yayoi 1-1-1, Bunkyo-ku, Tokyo 113, Japan (URL: http://hakone.eri.u-tokyo.ac.jp/vrc/erup/erup.html); Keizo Morita (URL: http://www.pmiyazaki.com/kirishima/tz/sinmoe/pano01.htm).

12/2010 (BGVN 35:12) Large eruption of Shinmoe-dake begins in January 2011

Setsuya Nakada (Volcano Research Center, University of Tokyo) reported that Subplinian and Vulcanian explosions occurred in the Kirishima Volcano Group in mid-January and at least as late as early February 2011. The event followed a year of inflation. The eruption occurred at Shinmoe-dake (Shinmoedake) volcano and included both airfall ash as well as the the birth and rapid growth of a lava dome. Small pyroclastic flows occurred, and over 1,000 residents evacuated.

After its 22 August 2008 eruption (BGVN 33:09), Shinmoe-dake went on to generate small phreatic explosions. These explosions took place on 15 November 2009 and 30 March, 11 April, and 27 May 2010.

Inflation preceded the 2011 eruption. the Geographical Survey Institute of Japan evaluated global positioning system (GPS) data for one year before the 2011 eruption. They found sufficient inflation to indicate the injection of 20 x 106 m3 of material.

According to the Japan Meteorological Agency (JMA), the eruption began, with a phreatomagmatic explosion from Shinmoe-dake on 19 January 2011. It produced a shock wave detected 12 km NE of the volcano, and an ash plume drifted SE. Ashfall up to 5 mm thick was reported in Miyakonojo (30 km SE) and in Nichinan City (60 km SE). Nakada reported that products of that explosion contained ~10% juvenile pumice.

Another explosion on 22 January 2011 ejected material 200 m above the vent. Based on reports from JMA and pilot observations, the Tokyo Volcanic Ash Advisory Center (VAAC) reported that ash plumes rose to altitudes of 1.8-2.1 km and drifted SE.

A third explosion began at 0731 on 26 January, and Subplinian explosions occurred at 1850 on 26 January, at 1541 on 27 January, and at 1247 on 28 January. Volcanic ash was emitted continuously until 30 January, when lava covered the crater floor.

The heights of the three major explosions during 26-28 January, confirmed with Doppler radar by JMA, were up to 8.5 km above the crater. Ashfall deposits were found ~17 cm thick at a distance of ~3 km SW of the crater, and ~8 cm thick at a distance of ~6 km from the crater.

Figures 11 and 12 are photos taken on 27 January amid the three major explosions of 26-28 January.

Figure 11. Eruption column generated by an explosion at 1541 on 27 January 2011 at Kirishma?s Shinmoedake crater. Taken ~3 km SW of the crater by Setsuya Nakada.
Figure 12. Continuously emitted Subplinean eruption cloud from Kirishima?s Shinmoedake crater seen in the late afternoon of 27 January 2011. Taken from 3 km WSW of the crater by S. Nakada.

According to the Earthquake Research Institute (ERI), the explosion on 26 January 2011 prompted JMA to raise the Alert Level to 3 (on a scale of 1-5). Lightning in the ash plume was visible in video footage that same day. Based on reports from JMA, analyses of satellite imagery, and pilot observations, the Tokyo VAAC reported that on 27 January ash plumes rose to altitudes of 1.8-2.1 km and drifted SE. According to news articles, tephra fell as far away as 8 km on 27 January and disrupted flights and train service. Some people in Miyazaki (55 km E from the volcano) voluntarily evacuated, and about 30 people in Takaharu (15 km E) spent the night in an evacuation center.

On 28 January, a small lava dome 200 m in diameter appeared on the crater floor near the vent (figure 13). In three days, it grew to ~600 m in diameter and attained a volume of more than 107 m3. ALOS satellite images disclosed that the dome grew to the point where it completely covered the active vent. Figure 14 shows the concentrically ringed and steaming lava dome on the crater floor as it appeared on 30 January.

Figure 13. Lava dome within Kirishima?s Shinmoe-dake crater, which appeared in the center of the crater floor, near the crater that produced Subplinian explosions (to the right in this photo). Taken by S. Nakada on 28 January 2011.

During an overflight on 29 January 2011, scientists from the ERI observed freshly erupted dome material on the crater floor and saw that the crater lake was gone. Fresh pyroclastic flow deposits in the SW crater had runout distances of 500-600 m.

On the night of 31 January, 1,158 people who lived in the Takaharu Town, ~12 km W of the crater and subject to potential pyroclastic flows, were ordered to evacuate due to a possibility of a Plinian explosion. As of 5 February, 73 people who lived less than 8 km from the crater were still in the process of evacuating.

A Vulcanian explosion started on 1 February 2011, destroying part of the dome. Volcanic ash rose about 7 km above the crater, according to JMA. Large ballistics 0.7 m in diameter landed 3.2 km W of the crater. Authorities established a zone of limited access within 4 km the crater. During subsequent Vulcanian explosions, the dome stopped growing. Its morphology flattened, and it became covered with its own ejecta.

Strong steam emanated from the dome's center on 4 February (figure 14). That day, Japan's Prime Minister delivered an address on the eruption at a meeting of government officials. They outlined responses and approaches to the crisis, including expanding the hazard zone, evacuation routes, countermeasures to lahars, and the danger of pyroclastic flows.

Figure 14. Westerly view of the lava dome growing in Kirishima?s Shinmoe-dake crater on 31 January 2011. Courtesy of Tetsuo Kobayashi (Kagoshima University).

Pumice from this eruption was composed of pyroxene-bearing andesite (57 to 62% SiO2), showing mingling of two magmas with different colors. The progress of this eruption seemed similar, Nakada noted, to the early stage of the volcano's 1716-1717 eruption. That eruption included a 3-month explosive phase, including five events with pyroclastic flows, for a total volume of erupted products amounting to 67 km3 DRE ('dense-rock equivalent,' the volume assuming no porosity, i.e., no bubbles). That eruption lasted for 1½ years (Imura and Kobayashi, 1991).

The eruption was studied from many perspectives, including satellite, seismic, magnetometer, GPS, tiltmeter, and infrasonic. Significant illustrations of data relating to the eruption have emerged, describing spatial distribution of plumes and deposits, geophysical, geochemical, petrographic, and other information only briefly covered here (ERI, 2011). Outstanding still and video images of the eruption appeared widely in the news and on the internet. No fatalities were cited in news reports accessed at press time in late February 2011.

References. ERI, 2011, Eruption of Shinmoe-dake (Kirishima volcano group), Japan, 2011; Earthquake Research Institute (ERI), Univ. of Tokyo (URL: outreach.eri.u-tokyo.ac.jp/eqvolc/201101_shinmoe/eng/).

Imura, R. and Kobayashi, T., 2001, Geological map of Kirishima Volcano (1:50,000), Geological Survey of Japan.

Imura, R. and Kobayashi, T., 1991. Eruptions of Shinmoedake Volcano, Kirishima Volcano Group, in the last 300 years, Bulletin of Volcanological Society of Japan, v. 36, pp.135-148 (in Japanese with abstract in English).

Information Contacts: Setsuya Nakada, Volcano Research Center, Earthquake Research Institute (VRC-ERI), University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113, Japan (URL: http://www.eri.u-tokyo.ac.jp/topics/ASAMA2004/index-e.html); Tetsuo Kobayashi, Graduate School of Science and Engineering, Kagoshima University, Kagoshima, Japan 890-006; Japan Meteorological Agency (JMA), Otemachi, 1-3-4, Chiyoda-ku Tokyo 100-8122, Japan (URL: http://www.jma.go.jp/jma/indexe.html); Tokyo Volcanic Ash Advisory Center (VAAC), Tokyo, Japan (URL: http://ds.data.jma.go.jp/svd/vaac/data/).

07/2011 (BGVN 36:07) February 2011 explosions launching ballistics; evacuations

Our last issue (BGVN 35:12) discussed the explosive eruptions and dome growth from early 2011 (19 January to about 4 February) from the summit crater of Kirishima's Shinmoe-dake. Vulcanian and Subplinian eruptions released enough ash to delay air traffic and prompt evacuations.

Regular ash plumes were observed above the volcano by pilots and with satellite imagery from January 2011 through March 2011 (table 2). More than 140 advisories were issued by the Tokyo Volcanic Ash Advisory Center (VAAC) since the eruption began in January, although only 14 were issued between April and July. Relying primarily on JMA data, this report presents a review of the monthly highlights, followed by a section with tilt, geodetic, and multi-year seismic data.

Table 2. Kirishima ash plumes reported from 22 January through 29 June 2011 based on JMA and VAAC reports with plume heights and drift directions. No plumes were reported for May or July.

    Date                Altitude (km)       Drift

    22 Jan 2011            1.8-2.1            SE
    26-27 Jan 2011         1.8-2.1            SE
    31 Jan 2011                2.1            SE
    02-08 Feb 2011         1.5-4.6            SE
    03 Feb 2011                9.1            NE
    09-11 Feb 2011         1.8-4.0           E, SE
    11, 14 Feb 2011        4.6-6.1             —
    18 Feb 2011                4.6             S
    24, 28 Feb 2011        1.8-2.1       N, E, and SE
    01, 03 Mar 2011            3.7            NE
    03, 04, 08 Mar 2011    1.5-3.0            SE
    13 Mar 2011            5.5-6.1             E
    23 Mar 2011                2.4            SE
    29 Mar 2011                2.1            SE
    03, 04 Apr 2011        4.6-6.1             E
    18 Apr 2011                3.7            SE
    23 Jun 2011                1.8             E
    29 Jun 2011            1.8-2.4             N

Peak of Kirishima's 2011 activity. The most dramatic events of the reporting interval took place on 1 and 14 February 2011. JMA field surveyors and local communities reported ballistics from Shinmoe-dake impacted areas up to 3.2 km SW from the crater; these volcanic bombs were from the 1 February eruption. Car windows, solar panels, and roofs were damaged from a shockwave and rock fragments that ranged from lapilli to bombs (up to 0.7 m) (figure 15).

Figure 15. JMA investigated several sites within 5 km of Kirishima's Shinmoe-dake, where damage from volcanic bombs was reported. The location map shows political boundaries (gray and green) and investigation sites (red squares). At Site 1, investigators found ballistics larger than 0.3 m; at Site 2, ballistics larger than 0.4 m; at Site 3, broken car windows; and at Site 4, damaged roofs. A map showing the volcano's location off the Korean Peninsula and the main islands of Japan appeared in BGVN 33:09. Courtesy of JMA.

The largest explosion, at 0754 on 1 February 2011, launched large blocks and juvenile material that impacted the forest to distances of 3.2 km from the crater. Kyushu University recorded oscillations from the impacts of some of these bombs. Investigators from the Earthquake Research Institute of the University of Tokyo visited an impact crater that was surrounded by broken trees; bomb fragments could be found more than 50 m from the crater. Charred wood was found beneath some of the bombs indicating that the material was still hot when it impacted the ground (personal communication, John Lyons, Michigan Technological University).

On 14 February, roofs were damaged when volcanic bombs traveled up to 16 km NE; JMA reported that strong winds that day contributed to these long dispersal distances. According to local news reports, bombs struck and damaged cars parked in the service area of Miyazaki Expressway and they shattered windows in Kobayashi, 13 km NE.

News reports relayed recommendations from civil authorities to evacuate 72,500 people from near Shinmoe-dake due to lahar hazards. Heavy rain had been falling since the previous day and in preparation for expected debris flows, authorities opened primary schools and community centers to shelter residents. At the time of the advisory, 63 people has already evacuated from Miyakonojo, 30 km SE of the crater region.

According to the JMA monthly report, incandescence was visible at night from 26 January to 10 February and also on 28 February. SO2 flux was 11,000-12,000 tons/day during January and averaged 600 tons/day on 25 February. There were 2,037 and 2,506 seismic events in January and February respectively. Tremor was continuous from 26 January to 7 February (a decrease occurred on 29 January). After 7 February, tremor was intermittent.

Activity during March 2011. On 1 March, ashfall was reported E of Shinmoe-dake and a shockwave was felt 3 km from the crater. Ash was deposited to the SW on 3 March and on 13 March ash was reported 60 km E over the Sea of Hyuga. As the intensity of ejections tapered off on 22 March, the restricted zone was reduced from 4 km to 3 km.

According to the monthly JMA report, a sensitive camera recorded night time glow from 1-14 March. SO2 flux averaged 1,300 tons/day on 2 March; however, on 8 March and six subsequent sampling days, the average was 200-500 tons/day. A total of 2,262 seismic events were recorded this month; continuous tremor was recorded from 28 February to 4 March.

Activity during April 2011. Ballistics on 3 April impacted areas as far as 600 m from the crater and ash traveled E to the Hyuga Sea. Ash from 9 April extended ENE and reached a town 60 km from the crater. Ballistics on 18 April impacted the local region as far as 1 km W and N; ash was reported 60 km E, and lapilli reached 9 km from the crater, damaging solar heaters and roof panels in the town of Takaharu.

According to JMA, the average SO2 flux on 2 and 21 April was 100-200 tons/day. A total of 3,840 seismic events were documented in the April report with hypocenters ~ 2 km below the crater; total tremor duration was 42 hours and 13 minutes.

Activity during May 2011. On 13 May, the average SO2 flux was measured at 200 tons/day according to JMA. Seismic stations detected 1,784 events with hypocenters between 0-2 km above sea level near Shinmoe-dake. Total duration of tremor was 1 hour 9 minutes.

Activity during June 2011. On 29 June, ash from an explosion was distributed N and reached the town of Itsuki ~ 50 km N from the crater. Ash from a 16 June eruption reached Takaharu and the city of Kobayashi, 15 km E of the crater. On the 23 June a smaller amount of ash was also observed in Kobayashi. No lapilli or ballistics were associated with these events. According to JMA, rainy weather (common in Japan during early summer) hampered direct observations of the crater. No gas or thermal data was collected. Seismic reports for June documented 4,096 events with hypocenters 0-2 km above sea level and the duration of tremor was 43 hours and 41 minutes.

Activity during July 2011. According to news reports, on 6 July advisories were issued throughout SE Kyushu for torrential rain hazards. Poor weather reduced direct observations of crater activity. JMA reported 3,764 seismic events during this period with 41 minutes of tremor. Earthquake hypocenters were in the same range as past months (0-2 km).

Tilt and geodetic data. Figure 16 plots multiple kinds of data collected during February-July 2011. During the reporting interval, tilt measurements typically indicated inflation on the flanks of Shinmoe-dake hours-to-several-days before explosive events occurred. Conversely, they recorded subsidence immediately after some eruptions. There were also cases of eruptions and explosive events not correlating with tilt. JMA interpreted tilt data as related to the intermittent ascent of magma moving from the chamber to the crater. GPS measurements since February 2011 by the Geospatial Information Authority of Japan suggested a deep magma supply centered several kilometers NW of Shinmoe-dake.

Figure 16. Data describing Kirishima for February-July 2011. Plotted together are earthquake counts (per day), rainfall (mm), tilt, eruptions, and ash plumes. Key: tremor "x", explosive eruptions (red triangles), ash plumes (gray triangles), and tilt records showing N-S (red) and E-W (blue). Earthquake counts and rainfall are presented in the black histograms. Lower panels show possible correlation between earthquakes and rainfall that started around 4-6 July 2011. Courtesy of JMA.

Multi-year seismic data. In the July report, JMA released continuous seismic data for Kirishima during June 2004 through July 2011. Epicenters were located for numerous earthquakes and appeared to concentrate within 2 km of the crater with depths less than 6 km (figure 17).

Figure 17. Epicenters at Kirishima's Shinmoe-dake as reported by JMA for the interval January 2004 to July 2011. Locations and depths are displayed in cross-sections, including, at right, two plots of earthquakes as a time series, tracking location with time (the lower two rectangles consist of, at left, a conventional E-W cross section, and, at right, the same data in the form of a time series). Note key for shading of data points. Courtesy of JMA.

During the explosive activity beginning in January 2011, more than 1,000 high frequency earthquakes occurred each month. High frequency (HF) earthquakes are defined as signals greater than 5 Hz (Ishihara and others, 2005). The total number of earthquakes increased and appeared to peak in June with 4,096 high-frequency earthquakes.

Visible and thermal aerial observations. Rapid growth of a lava dome within the Shinmoe-dake crater began on 28 January and was closely monitored by aerial observations. Over the course of 3 days, the dome reached a volume of more than 107 m3 and sustained a diameter of ~ 600 m (BGVN 35:12). Collaboration between the Japan Ground and Air Self-Defense Force (JGSDF-JASDF) provided numerous thermal images as recent as 31 May. During four separate flights in May, white plumes were observed from the SE parts of the dome margin. These plumes reached 50-100 m above the crater rim. Infrared imagery taken during JGSDF-JASDF flights showed no major change since February regarding the heat distribution across the dome and within the crater region. The highest temperatures measured during these flights corresponded to the plume area and the size of the dome had not changed since emplacement.

The Tokyo VAAC reported that on 23 and 29 June, eruptions from Shinmoe-dake produced plumes that rose to an altitude of 1.8 km and 1.8-2.4 km respectively, the first drifted E and the second drifted N. The VAAC reported another eruption on 6 August.

Reference. Ishihara, K., Tameguri, T., Igushi, M., 2005, Automated Classification of Volcanic Earthquakes and Tremors-Outline of the system and preliminary experiment, Annuals of Disaster Prevention Research Institute, Kyoto University, No. 48C.

Information Contacts: Volcano Research Center, Earthquake Research Institute (VRC-ERI), University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113, Japan (URL: http://www.eri.u-tokyo.ac.jp/topics/ASAMA2004/index-e.html); Japan Meteorological Agency (JMA), Otemachi, 1-3-4, Chiyoda-ku Tokyo 100-8122, Japan (URL: http://www.jma.go.jp/jma/indexe.html); Tokyo Volcanic Ash Advisory Center (VAAC), Tokyo, Japan (URL: http://ds.data.jma.go.jp/svd/vaac/data/); Yukio Hayakawa, Gunma University, Faculty of Education, Aramaki 4-2, Maebashi 371-8510, Japan; John Lyons, Michigan Technological University, Dept. of Geological and Mining Engineering and Sciences, 1400 Townsend Drive, Houghton MI, 49931, USA (URL: http://www.geo.mtu.edu/~jlyons/); News On Japan (URL: http://www.newsonjapan.com/); Japan Today (URL: http://www.japantoday.com/); Daily Mail (URL: http://www.dailymail.co.uk/).

07/2012 (BGVN 37:07) Gradual decline in activity following explosive 2011 eruptions

The early 2011 eruption of Shinmoe-dake (Shinmoedake) volcano of the Kirishima Volcanic Group was characterized by sub-Plinian and Vulcanian explosions and an ~600-m-diameter lava dome that was extruded into the crater (BGVN 35:12 and 36:07, reports covering through July 2011). Fewer eruptions occurred during an ensuing decline in activity, where plumes only rose to up to 1 km above the summit. No explosions (defined as accompanying an air shock larger than 20 Pa and explosive earthquake signals) were reported by the Japan Meteorological Agency (JMA) after 11 May 2011 and through June 2012. This report discusses diminishing plume emissions and seismicity during September 2011-June 2012, and supplies more context on the entire eruptive episode. The material in this report is based on JMA monthly reports, which are now available in English with coverage starting in October 2010.

2011 eruption wanes. After the explosive eruptions during January-February 2011, eruptions (ash emissions) at Shinmoe-dake occurred through 7 September 2011. After that, JMA reported no further eruptions at least through June 2012; gas-and-steam plumes rose to a maximum of ~600 m above the crater of Shinmoe-dake after 7 September 2011 (figure (18).

Figure 18. Plume behavior and seismicity at Kirishima during intervals bracketing the explosive activity of January-May 2011. The inset plot shows daily maximum plume heights (black bars, in meters above the summit) and eruptions (red arrows) since 2008, with the yellow shaded area indicating the temporal coverage of the main plot. The main plot shows maximum plume heights per month (kilometers above sea level, km a.s.l., right axis, where gray bars indicate months in which plumes contained ash, and white bars indicate months in which ash was absent in all plumes) and seismicity (seismic events per month, black line, left axis). Coverage of previous Bulletin reports is indicated at the top of the plot. Data and inset plot courtesy of JMA.

Elevated seismicity continued following the cease of explosive eruptions in May 2011, but a substantial protracted decline too place during August-November 2011. In May and June 2012, JMA reported that seismicity had returned to background levels seen prior to the onset of the early 2011 explosive activity, and they reported an absence of measured tremor over the same two months (figures 18 and 19).

Figure 19. Kirishima’s daily high-frequency (H-F) earthquake counts plotted with tilt measurements (E-W component shown in blue, N-S component shown in red), indications of tremor (black x’s, top), ash eruptions (gray volcano symbols) and explosions (red volcano symbols) during January 2011-June 2012 at Shinmoe-dake. The black arrow indicates a tilt change of 4 microradians (µrad); the blue (E-W) and red (N-S) triangles indicate the start and end points of the tilt component records. Courtesy of JMA.

JMA reported that GPS baseline extension indicated “magma supply to a deeper chamber several kilometers northwest of the crater” through December 2011; the baseline extension slowed after December. JMA initially reported almost no change after January 2012, but during June 2012 the baseline distance between Ebino (~16 km NNW) and Makizono (~14 km WSW) shortened.

Observation flights conducted through various collaborations between the Japan Ground, Air, and Maritime Self-Defense Forces (JGSDF, JASDF, and JMSDF, respectively) and the Ministry of Land, Infrastructure, Transportation and Tourism (MLIT) allowed frequent aerial photography and infrared thermal measurements of the crater and edifice of Shinmoe-dake. The diameter of the lava dome within the crater remained ~600 m as of June 2012 (indicating little-to-no growth since 30 January 2011). Infrared thermal photography revealed little thermal structure to the dome, but highlighted comparatively high-temperature areas at its margins. A fissure (described as a “crack” by JMA) located on the W slope of the edifice was occasionally reported to emit plumes, and exhibited an elevated temperature compared with the rest of the edifice (figure 20). Similar aerial and thermal observations were reported as late as 10 May 2012.

Figure 20. Aerial photograph (top) and infrared thermal image (bottom) of the summit of Shinomoe-dake volcano on 21 February 2012, illustrating a high-temperature anomaly that occurred within a fissure (described as a “crack” by JMA) on the W slope, where plumes were occasionally observed (labeled with ‘*’). For orientation, the same symbol is placed just S of the same approximate location in the aerial photo (top). Courtesy of JMSDF, MLIT, and JMA.

The Alert Level remained at 3 (on a scale from 1-5) at the end of June 2012.

Information Contacts: Japan Meteorological Agency (JMA), Otemachi, 1-3-4, Chiyoda-ku Tokyo 100-8122, Japan (URL: http://www.jma.go.jp/jma/indexe.html); Japan Ground Self-Defense Force (JGSDF) (URL: http://www.mod.go.jp/gsdf/english/index.html); Japan Air Self-Defense Force (JASDF) (URL: http://www.mod.go.jp/asdf/English_page/organization/formation01/); Japan Maritime Self-Defense Force (JMSDF) (URL: http://www.mod.go.jp/msdf/formal/english/index.html); Ministry of Land, Infrastructure, Transportation and Tourism (MLIT) (URL: http://www.mlit.go.jp/en/index.html).

Kirishimayama is a large group of more than 20 Quaternary volcanoes located north of Kagoshima Bay. The late-Pleistocene to Holocene dominantly andesitic group consists of stratovolcanoes, pyroclastic cones, maars, and underlying shield volcanoes located over an area of 20 x 30 km. The larger stratovolcanoes are scattered throughout the field, with the centrally located, 1700-m-high Karakunidake being the highest. Onamiike and Miike, the two largest maars, are located SW of Karakunidake and at its far eastern end, respectively. Holocene eruptions have been concentrated along an E-W line of vents from Miike to Ohachi, and at Shinmoedake to the NE. Frequent small-to-moderate explosive eruptions have been recorded since the 8th century.

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

Start Date Stop Date Eruption Certainty VEI Evidence Activity Area or Unit
2011 Jan 19 2011 Sep 7 Confirmed 2 Historical Observations Shinmoe-dake
2010 Mar 30 2010 Jul 10 Confirmed 1 Historical Observations Shinmoe-dake
2009 Nov 15 2009 Nov 15 Confirmed 1 Historical Observations Shinmoe-dake
2008 Aug 22 2008 Aug 22 Confirmed 1 Historical Observations Shinmoe-dake crater and W flank
1991 Dec 1 1992 Apr 19 Confirmed 1 Historical Observations Shinmoe-dake
1979 Feb 16 ± 60 days Unknown Confirmed 1 Historical Observations Shinmoe-dake
1971 Aug 5 1971 Aug 5 Confirmed 1 Historical Observations North foot, near Tearai hot springs
1959 Feb 13 1959 Feb 17 Confirmed 2 Historical Observations Shinmoe-dake
[ 1946 Apr ] [ Unknown ] Uncertain 2   Karakuni-dake ?
[ 1934 ] [ Unknown ] Discredited    
1923 Jul 1923 Jul Confirmed 2 Historical Observations Ohachi
1914 Nov 8 Unknown Confirmed   Historical Observations Ohachi
1913 Nov 8 1914 Jan 8 Confirmed 2 Historical Observations Ohachi
1903 Aug 29 1903 Nov 25 Confirmed 2 Historical Observations Ohachi
1899 Jul 28 1900 Feb 16 Confirmed 2 Historical Observations Ohachi
1898 Dec 26 1898 Dec 30 Confirmed 2 Historical Observations Ohachi
1898 Feb 8 1898 Mar 11 Confirmed 2 Historical Observations Ohachi
1897 May 3 1897 Sep 4 Confirmed 2 Historical Observations Ohachi
1896 Dec 21 Unknown Confirmed 2 Historical Observations Ohachi
1895 Jul 16 1896 Jun 26 Confirmed 2 Historical Observations Ohachi
1894 Feb 25 1894 Feb 28 (?) Confirmed 2 Historical Observations Ohachi
1891 Nov 10 1891 Nov 20 (?) Confirmed 2 Historical Observations Ohachi
1891 Jun 19 (?) Unknown Confirmed 2 Historical Observations Ohachi
1889 Dec 10 1889 Dec 18 Confirmed 2 Historical Observations Ohachi
1888 Feb 21 1888 May 9 Confirmed 2 Historical Observations Ohachi
1887 May Unknown Confirmed 2 Historical Observations Ohachi
1880 Sep Unknown Confirmed 2 Historical Observations Ohachi
1832 Apr 20 Unknown Confirmed 2 Historical Observations Shinmoe-dake
1822 Jan 12 Unknown Confirmed 2 Historical Observations Shinmoe-dake, Tephra layer Sm-BP
1771 1772 Confirmed 2 Historical Observations Shinmoe-dake
1769 Unknown Confirmed 2 Historical Observations Ohachi
1768 Unknown Confirmed 0 Historical Observations Iwo-yama (NW flank of Karakuni-dake)
1719 Unknown Confirmed 2 Historical Observations Shinmoe-dake
1717 Sep 19 Unknown Confirmed 3 Historical Observations Shinmoe-dake, Tephra layer Sm-KP7
1716 Nov 9 1717 Feb 13 Confirmed 3 Historical Observations Shinmoe-dake
1716 Mar 11 Unknown Confirmed 3 Historical Observations Shinmoe-dake
1706 Jan 28 Unknown Confirmed 2 Historical Observations Ohachi
1690 Unknown Confirmed 2 Historical Observations Ohachi
1678 Feb 29 Unknown Confirmed 2 Historical Observations Ohachi
1677 Unknown Confirmed 2 Historical Observations Ohachi
[ 1667 ] [ Unknown ] Uncertain     Ohachi
1662 Sep 1664 Confirmed 2 Historical Observations Ohachi
1659 Feb 1661 Confirmed 2 Historical Observations Ohachi
1637 1638 Confirmed 2 Historical Observations Shinmoe-dake
1628 Oct 26 Unknown Confirmed 2 Historical Observations Ohachi
1620 Unknown Confirmed 2 Historical Observations
1615 1618 Confirmed 2 Historical Observations Ohachi
1613 1614 Confirmed 2 Historical Observations Ohachi
1598 1600 Confirmed 2 Historical Observations Ohachi
[ 1596 ] [ Unknown ] Uncertain 2  
1595 Unknown Confirmed 2 Historical Observations
1588 Apr 7 Unknown Confirmed 2 Historical Observations Ohachi
1587 May 24 Unknown Confirmed 2 Historical Observations Ohachi
1585 Nov (?) Unknown Confirmed 2 Historical Observations Ohachi
1576 1578 Confirmed 2 Historical Observations Ohachi
1574 Feb Unknown Confirmed 2 Historical Observations Ohachi
1566 Oct 31 Unknown Confirmed 3 Historical Observations Ohachi
1566 May 6 Unknown Confirmed 2 Historical Observations
1554 Unknown Confirmed 2 Historical Observations Ohachi
1524 Unknown Confirmed 2 Historical Observations Ohachi
[ 1381 ] [ Unknown ] Uncertain 2  
1235 Jan 25 Unknown Confirmed 4 Historical Observations Ohachi, Takahara Tephra
1184 Feb 7 Unknown Confirmed 2 Historical Observations Ohachi
[ 1175 Jan (?) ] [ Unknown ] Uncertain 2  
1167 Unknown Confirmed 2 Historical Observations Ohachi
1113 Feb 27 Unknown Confirmed 2 Historical Observations
1112 Mar 9 Unknown Confirmed 2 Historical Observations Ohachi
1000 (?) Unknown Confirmed   Tephrochronology Ohachi, Miyasugi Tephra
0945 Unknown Confirmed 2 Historical Observations
0858 Unknown Confirmed 2 Historical Observations
0857 Unknown Confirmed 2 Historical Observations
0843 0848 Confirmed 2 Historical Observations
0837 0839 (?) Confirmed 3 Historical Observations Ohachi
0788 Apr 18 Unknown Confirmed 4 Historical Observations Ohachi (Katazoe Scoria)
0742 Dec 28 Unknown Confirmed 3 Historical Observations Ohachi
0700 (?) Unknown Confirmed   Tephrochronology Ohachi, Araso tephra
2050 BCE (?) Unknown Confirmed 3 Radiocarbon (uncorrected) Shinmoe-dake (Mae-yama Pumice)
2650 BCE (?) Unknown Confirmed 4 Radiocarbon (uncorrected) Mi-ike, Tephra layer Kr-M
3050 BCE (?) Unknown Confirmed 3 Tephrochronology Takachiho-mine, Oji Scoria
3550 BCE (?) Unknown Confirmed 3 Tephrochronology Takachiho-mine (Mojihara Ash)
4350 BCE (?) Unknown Confirmed 4 Radiocarbon (uncorrected) Old Takachiho, Ushinosune Ash
5700 BCE ± 1350 years Unknown Confirmed 3 Tephrochronology Old Takachiho, Uramuta Scoria
7050 BCE ± 2350 years Unknown Confirmed 3 Tephrochronology Shinmoe-dake (Setao Pumice)

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

Kirisima | Kirishima

Cones

Feature Name Feature Type Elevation Latitude Longitude
Ebino-dake Stratovolcano 1305 m
Eboshi-dake
    Ebosi-dake
Cone 988 m
Futagoishi Stratovolcano
Futatsu-ishi Stratovolcano
Hinamori-dake Stratovolcano 1344 m
Iimori-yama Stratovolcano 846 m
Karakuni-dake Stratovolcano 1700 m
Koshiki-dake
    Kosiki-dake
Cone 1301 m
Kurino-dake Stratovolcano 1094 m
Maruoka-yama Cone
Naka-dake Stratovolcano 1332 m
Ohata-yama Stratovolcano 1353 m
Shinmoe-dake
    Sinmoe-dake
Stratovolcano 1421 m
Shiratori-yama
    Siratori-yama
Stratovolcano 1363 m
Shishido-dake
    Sisido-dake
Stratovolcano 1428 m
Takachihomine
    Takatihomine
Stratovolcano 1573 m
Yatake Stratovolcano 1132 m
Yunotani-dake Stratovolcano

Craters

Feature Name Feature Type Elevation Latitude Longitude
Biwa-ike Crater
Byakushi-ike
    Byakusi-ike
Crater
Fudo-ike
    Hudo-ike
Crater
Mi-ike Maar
Ohachi
    Ohati
Crater
Ohata-ike Crater
Onami-ike
    Oonami-ike
Crater 1411 m
Rokkannon-Mi-ike Maar

Domes

Feature Name Feature Type Elevation Latitude Longitude
Iwo-yama Dome
Steam rises from Iwo-yama ("Sulfur Mountain"), one of the largest thermal areas of the Kirishima volcano group. The Iwo-yama thermal area is located between Karakuni-dake stratovolcano and Rokannon-Mi-ike maar in the NW part of the volcanic field.

Photo by Lee Siebert, 1988 (Smithsonian Institution).
Lake-filled Rokkannon-Mi-ike is one of several maars in the Kirishima volcano group. It is located NW of Karakuni-dake in the NW part of the Kirishima group. The forested rim of the maar cuts horizontally across the center of the photo; the peak behind it is Shiratori-yama, a small stratovolcano.

Photo by Lee Siebert, 1988 (Smithsonian Institution).
Lake-filled Rokkannon-Mi-ike, its rim traversed by a highway, is one of several maars at Kirishima volcano. The Kirishima volcano group consists of stratovolcanoes, pyroclastic cones, maars, and underlying shield volcanoes scattered over a 20 x 30 km area north of Kagoshima Bay. Numerous small-to-moderate explosive eruptions have been recorded at Kirishima since the 8th century.

Photo by Yukio Hayakawa (Gunma University).
Sharp-peaked Takachiho-mine (center) is the 2nd highest peak of the Kirishima volcanic complex. It is flanked on the east (right) by Ohachi, with its broad summit crater. Madu-dake is the grass-covered cone at the far right. Kirishima is a large group of more than 20 Quaternary volcanoes that is the centerpiece of Kirishima National Park, located north of Kagoshima Bay. The late-Pleistocene to Holocene group of stratovolcanoes, pyroclastic cones, maars, and underlying shield volcanoes occupies an area of 20 x 30 km.

Photo by Ichio Moriya (Kanazawa University).

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.

Imura R, Kobayashi T, 1991. Eruptions of Shinmoedake volcano, Kirishima volcano group, in the last 300 years. Bull Volc Soc Japan (Kazan), 36: 135-148 (in Japanese).

Inoue K, 1988. The growth history of Takachiho composite volcano in the Kirishima volcano group. Ganko (Petr Min), 83: 26-41 (in Japanese with English abs).

Japan Meteorological Agency, 1996. National Catalogue of the Active Volcanoes in Japan (second edition). Tokyo: Japan Meteorological Agency, 502 p (in Japanese).

Japan Meteorological Agency, 2013. National Catalogue of the Active Volcanoes in Japan (fourth edition, English version). Japan Meteorological Agency.

Kobayashi T, Aramaki S, Watanabe T, Kamada M, 1981. Kirishima volcano. In: Kubotera A (ed) {Symp Arc Volc Field Excur Guide to Sakurajima, Kirishima and Aso Volcanoes, Part 2}, Tokyo: Volc Soc Japan, p 18-32.

Kuno H, 1962. Japan, Taiwan and Marianas. Catalog of Active Volcanoes of the World and Solfatara Fields, Rome: IAVCEI, 11: 1-332.

Nakano S, Yamamoto T, Iwaya T, Itoh J, Takada A, 2001-. Quaternary Volcanoes of Japan. Geol Surv Japan, AIST, http://www.aist.go.jp/RIODB/strata/VOL_JP/.

Tsukui M, Okuno M, Kobayashi T, 2007. Eruptive history of Ohachi volcano, Kirishima volcano group, southern Kyushu, Japan. Bull Volc Soc Japan (Kazan), 52: 1-21 (in Japanese with English abs).

Volcano Types

Shield
Stratovolcano(es)
Pyroclastic cone(s)

Tectonic Setting

Subduction zone
Continental crust (> 25 km)

Rock Types

Major
Andesite / Basaltic Andesite
Basalt / Picro-Basalt
Dacite

Population

Within 5 km
Within 10 km
Within 30 km
Within 100 km
647
8,415
407,050
3,972,044

Affiliated Databases

Large Eruptions of Kirishimayama 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.