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Kikai

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  • Country
  • Volcanic Region
  • Landform | Volc Type
  • Last Known Eruption
  • 30.793°N
  • 130.305°E

  • 704 m
    2,310 ft

  • 282060
  • Latitude
  • Longitude

  • Summit
    Elevation

  • Volcano
    Number

Most Recent Weekly Report: 4 September-10 September 2024 Citation IconCite this Report

JMA reported that no activity at Iodake Crater located at Satsuma Iwo-jima, a subaerial part of Kikai’s NW caldera rim, was detected after the 1 and 3 September eruptive events. Crater incandescence continued to be observed at night. The Alert Level remained at 2 (on a 5-level scale), and residents were warned to stay 500 m away from Iodake Crater.

Source: Japan Meteorological Agency (JMA)


Most Recent Bulletin Report: May 2023 (BGVN 48:05) Citation IconCite this Report

Intermittent white gas-and-steam plumes, discolored water, and seismicity during May 2021-April 2023

Kikai, located just S of the Ryukyu islands of Japan, contains a 19-km-wide mostly submarine caldera. The island of Satsuma Iwo Jima (also known as Satsuma-Iwo Jima and Tokara Iojima) is located at the NW caldera rim, as well as the island’s highest peak, Iodake. Its previous eruption period occurred on 6 October 2020 and was characterized by an explosion and thermal anomalies in the crater (BGVN 45:11). More recent activity has consisted of intermittent thermal activity and gas-and-steam plumes (BGVN 46:06). This report covers similar low-level activity including white gas-and-steam plumes, nighttime incandescence, seismicity, and discolored water during May 2021 through April 2023, using information from the Japan Meteorological Agency (JMA) and various satellite data. During this time, the Alert Level remained at a 2 (on a 5-level scale), according to JMA.

Activity was relatively low throughout the reporting period and has consisted of intermittent white gas-and-steam emissions that rose 200-1,400 m above the Iodake crater and nighttime incandescence was observed at the Iodake crater using a high-sensitivity surveillance camera. Each month, frequent volcanic earthquakes were detected, and sulfur dioxide masses were measured by the University of Tokyo Graduate School of Science, Kyoto University Disaster Prevention Research Institute, Mishima Village, and JMA (table 6).

Table 6. Summary of gas-and-steam plume heights, number of volcanic earthquakes detected, and amount of sulfur dioxide emissions in tons per day (t/d). Courtesy of JMA monthly reports.

Month Max plume height (m) Volcanic earthquakes Sulfur dioxide emissions (t/d)
May 2021 400 162 900-1,300
Jun 2021 800 117 500
Jul 2021 1,400 324 800-1,500
Aug 2021 1,000 235 700-1,000
Sep 2021 800 194 500-1,100
Oct 2021 800 223 600-800
Nov 2021 900 200 400-900
Dec 2021 1,000 161 500-1,800
Jan 2022 1,000 164 600-1,100
Feb 2022 1,000 146 500-1,600
Mar 2022 1,200 171 500-1,200
Apr 2022 1,000 144 600-1,000
May 2022 1,200 126 300-500
Jun 2022 1,000 154 400
Jul 2022 1,300 153 600-1,100
Aug 2022 1,100 109 600-1,500
Sep 2022 1,000 170 900
Oct 2022 800 249 700-1,200
Nov 2022 800 198 800-1,200
Dec 2022 700 116 600-1,500
Jan 2023 800 146 500-1,400
Feb 2023 800 135 600-800
Mar 2023 1,100 94 500-600
Apr 2023 800 82 500-700

Sentinel-2 satellite images show weak thermal anomalies at the Iodake crater on clear weather days, accompanied by white gas-and-steam emissions and occasional discolored water (figure 24). On 17 January 2022 JMA conducted an aerial overflight in cooperation with the Japan Maritime Self-Defense Force’s 1st Air Group, which confirmed a white gas-and-steam plume rising from the Iodake crater (figure 25). They also observed plumes from fumaroles rising from around the crater and on the E, SW, and N slopes. In addition, discolored water was reported near the coast around Iodake, which JMA stated was likely related to volcanic activity (figure 25). Similarly, an overflight taken on 11 January 2023 showed white gas-and-steam emissions rising from the Iodake crater, as well as discolored water that spread E from the coast around the island. On 14 February 2023 white fumaroles and discolored water were also captured during an overflight (figure 26).

Figure (see Caption) Figure 24. Sentinel-2 satellite images of Satsuma Iwo Jima (Kikai) showing sets of visual (true color) and infrared (bands 12, 11, 8a) views on 7 December 2021 (top), 23 October 2022 (middle), and 11 January 2023 (bottom). Courtesy of Copernicus Browser.
Figure (see Caption) Figure 25. Aerial image of Satsuma Iwo Jima (Kikai) showing a white gas-and-steam plume rising above the Iodake crater at 1119 on 17 January 2022. There was also green-yellow discolored water surrounding the coast of Mt. Iodake. Courtesy of JMSDF via JMA.
Figure (see Caption) Figure 26. Aerial image of Satsuma Iwo Jima (Kikai) showing white gas-and-steam plumes rising above the Iodake crater on 14 February 2023. Green-yellow discolored water surrounded Mt. Iodake. Courtesy of JCG.

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 Coast Guard (JCG) Volcano Database, Hydrographic and Oceanographic Department, 3-1-1, Kasumigaseki, Chiyoda-ku, Tokyo 100-8932, Japan (URL: https://www1.kaiho.mlit.go.jp/kaiikiDB/kaiyo30-2.htm); Copernicus Browser, Copernicus Data Space Ecosystem, European Space Agency (URL: https://dataspace.copernicus.eu/browser/).

Weekly Reports - Index


2024: August | September
2023: March | July
2022: March | November
2021: March
2020: April | September
2019: October
2018: March | April
2013: May
2004: March | May | August | September
2002: May | June
2001: July


4 September-10 September 2024 Citation IconCite this Report

JMA reported that no activity at Iodake Crater located at Satsuma Iwo-jima, a subaerial part of Kikai’s NW caldera rim, was detected after the 1 and 3 September eruptive events. Crater incandescence continued to be observed at night. The Alert Level remained at 2 (on a 5-level scale), and residents were warned to stay 500 m away from Iodake Crater.

Source: Japan Meteorological Agency (JMA)


28 August-3 September 2024 Citation IconCite this Report

JMA reported that an eruptive event at Iodake Crater located at Satsuma Iwo-jima, a subaerial part of Kikai’s NW caldera rim, was recorded at 1128 on 1 September. An ash plume rose 1 km above the crater rim. The report noted that there was no change in the number of earthquakes either before or after the event, and no volcanic tremors were recorded. An eruptive event at 1008 on 3 September generated a volcanic plume that rose 700 m above the crater rim. Crater incandescence continued to be observed at night. The 1 September event was the first eruptive activity since 6 October 2020. The Alert Level remained at 2 (on a 5-level scale), and residents were warned to stay 500 m away from Iodake Crater.

Source: Japan Meteorological Agency (JMA)


26 July-1 August 2023 Citation IconCite this Report

JMA reported that minor eruptive activity was recorded at Satsuma Iwo-jima, a subaerial part of Kikai’s NW caldera rim, during 24-31 July. White gas-and-steam plumes rose 600 m above the crater rim. Surveillance cameras observed nightly incandescence. The Alert Level remained at 2 (on a 5-level scale), and residents were warned to stay 500 m away from the crater.

Source: Japan Meteorological Agency (JMA)


29 March-4 April 2023 Citation IconCite this Report

JMA reported that minor eruptive activity was recorded at Satsuma Iwo-jima, a subaerial part of Kikai’s NW caldera rim, during 27 March-3 April. White gas-and-steam plumes rose 700 m above the crater rim. Surveillance cameras observed nightly incandescence. The Alert Level remained at 2 (on a 5-level scale), and residents were warned to stay 500 m away from the crater.

Source: Japan Meteorological Agency (JMA)


9 November-15 November 2022 Citation IconCite this Report

JMA reported that minor eruptive activity continued to be recorded at Satsuma Iwo-jima, a subaerial part of Kikai’s NW caldera rim, during 7-14 November. White gas-and-steam plumes rose 600 m above the crater rim. Surveillance cameras observed nightly incandescence. The Alert Level remained at 2 (on a 5-level scale), and residents were warned to stay 500 m away from the crater.

Source: Japan Meteorological Agency (JMA)


30 March-5 April 2022 Citation IconCite this Report

JMA reported that eruptive activity continued to be recorded at Satsuma Iwo-jima, a subaerial part of Kikai’s NW caldera rim, during 29 March through 4 April. White gas-and-steam plumes rose 1 km above the crater rim. Surveillance cameras observed nightly incandescence. The Alert Level remained at 2 (on a 5-level scale), and residents were warned to stay 500 m away from the crater.

Source: Japan Meteorological Agency (JMA)


3 March-9 March 2021 Citation IconCite this Report

In response to an eruption at Satsuma Iwo-jima, a subaerial part of Kikai’s NW caldera rim, on 2 November 2019 JMA had raised the Alert Level to 2 (on a 5-level scale). Since then, surveillance cameras sometimes recorded minor incandescence reflected in emitted plumes. On 8 March JMA revised the Alert Level guidelines, keeping the level at 2, but reducing the exclusion zone around the crater from 1 km to 500 m.

Source: Japan Meteorological Agency (JMA)


30 September-6 October 2020 Citation IconCite this Report

JMA reported that at 0757 on 6 October an eruption at Satsuma Iwo-jima, a subaerial part of Kikai’s NW caldera rim, generated a volcanic plume that rose 200 m above the Iodake crater rim. The Alert Level remained at 2 (on a 5-level scale).

Source: Japan Meteorological Agency (JMA)


8 September-14 September 2020 Citation IconCite this Report

JMA reported that during 7-14 September white plumes from Satsuma Iwo-jima, a subaerial part of Kikai’s NW caldera rim, rose as high as 1 km above the Iodake crater rim. Incandescence from the crater was visible at night. The Alert Level remained at 2 (on a 5-level scale).

Source: Japan Meteorological Agency (JMA)


29 April-5 May 2020 Citation IconCite this Report

An eruption at 0609 on 29 April at Satsuma Iwo-jima, a subaerial part of Kikai’s NW caldera rim, generated a volcanic plume that rose 1 km above the crater. This was the first eruption recorded since 2 November 2019. The Alert Level remained at 2 (on a 5-level scale).

Source: Japan Meteorological Agency (JMA)


30 October-5 November 2019 Citation IconCite this Report

An eruption at Satsuma Iwo-jima, a subaerial part of Kikai’s NW caldera rim, was detected at 1735 on 2 November, prompting JMA to raise the Alert Level to 2 (on a 5-level scale). A grayish-white plume rose 1 km above the Iodake crater rim. The report noted that the number of volcanic earthquakes has been low, with no variations before or after the event. The next day during an overflight conducted by the Coast Guard and the Japan Meteorological Agency Mobile Survey Team (JMA-MOT) observers noted no changes to the geothermal field and no new deposits from the event the day before. Views of the crater were obscured by white plumes rising 300 m above the crater rim.

Source: Japan Meteorological Agency (JMA)


25 April-1 May 2018 Citation IconCite this Report

JMA reported that the number of volcanic earthquakes at Satsuma Iwo-jima, a subaerial part of Kikai’s NW caldera rim, was low during 20-26 April. White plumes rose as high as 700 m above the Iwo-dake lava dome; incandescence from the crater had not been visible since 12 April. During field surveys on 25 and 26 April observers noted a slight expansion of a thermally anomalous area compared to 24-25 March observations, and a decrease in sulfur dioxide flux from 600 tons/day on 24 March to 300 tons/day. The Alert Level was reduced to 1 (on a 5-level scale) on 27 April.

Source: Japan Meteorological Agency (JMA)


28 March-3 April 2018 Citation IconCite this Report

JMA reported that the number of volcanic earthquakes at Satsuma Iwo-jima, a subaerial part of Kikai’s NW caldera rim, was low during 27 March-2 April after an increase recorded during 22-23 March. White plumes rose as high as 1.8 km above the Iwo-dake lava dome. Incandescence from the crater was visible at night during 27-28 March. The Alert Level remained at 2 (on a 5-level scale).

Source: Japan Meteorological Agency (JMA)


14 March-20 March 2018 Citation IconCite this Report

JMA reported that one small-amplitude, short-duration volcanic tremor was detected on 16 March at Satsuma Iwo-jima, a subaerial part of Kikai’s NW caldera rim. The number of volcanic earthquakes increased on 19 March, prompting JMA to raise the Alert Level to 2 (on a 5-level scale), and then decreased the next day. The report noted increased thermal activity since February, with occasional visual observations of incandescence.

Source: Japan Meteorological Agency (JMA)


29 May-4 June 2013 Citation IconCite this Report

Based on information from JMA, the Tokyo VAAC reported that on 4 June an ash plume from Kikai drifted W.

Source: Tokyo Volcanic Ash Advisory Center (VAAC)


22 September-28 September 2004 Citation IconCite this Report

Based on information from JMA, the Tokyo VAAC reported that an eruption at Kikai on 25 September at 0937 produced a plume to a height of ~1.5 km a.s.l. that extended W.

Source: Tokyo Volcanic Ash Advisory Center (VAAC)


11 August-17 August 2004 Citation IconCite this Report

Based on information from JMA, the Tokyo VAAC reported that an eruption at Kikai around 1105 on 13 August produced a plume to a height of ~1.2 km a.s.l. The plume drifted NW.

Source: Tokyo Volcanic Ash Advisory Center (VAAC)


26 May-1 June 2004 Citation IconCite this Report

Based on information from JMA, the Tokyo VAAC reported that Kikai erupted on 1 June at 1330. The resultant ash cloud rose to an unknown height and drifted W.

Source: Tokyo Volcanic Ash Advisory Center (VAAC)


24 March-30 March 2004 Citation IconCite this Report

Based on information from the Japanese Meteorological Agency, the Tokyo VAAC reported that Kikai erupted on 24 March at 1755 and on 25 March at 0715, producing plumes that reached a height of ~1.5 km a.s.l. and extended S and NW, respectively. No ash was visible on satellite imagery.

Source: Tokyo Volcanic Ash Advisory Center (VAAC)


3 March-9 March 2004 Citation IconCite this Report

Based on information from the Japanese Meteorological Agency, the Tokyo VAAC reported that an eruption at Kikai on 5 March at 0922 produced a N-drifting plume to ~1.5 km a.s.l. No ash was detected on satellite imagery.

Source: Tokyo Volcanic Ash Advisory Center (VAAC)


5 June-11 June 2002 Citation IconCite this Report

According to JMA's report on 6 June, discolored plumes, associated with volcanic tremor, had intermittently issued from Kikai's summit since 11 May. In addition, the number of small volcanic earthquakes had increased since 29 May. Discolored plumes were observed from Mishima village on the Ryukyu Islands and ash fell on residential areas during 3-5 June. The Air Force Weather Agency reported that low-level plumes were visible on satellite imagery during 1-4 June.

Sources: US Air Force Weather Agency; Japan Meteorological Agency (JMA) via the Volcano Research Center


29 May-4 June 2002 Citation IconCite this Report

The Air Force Weather Agency reported that plumes were visible on satellite imagery emanating from Kikai during 24-28 May. The thin plumes drifted to the S on the 24th, SE on the 25th and 26th, S on the 27th, and E on the 28th. The plumes were estimated to be lower than 3 km a.s.l. Ash was seen from the island of Yaku-shima on 26 May during 1600-1800. After 29 May the area was covered with meteorological clouds, preventing satellite observations.

Source: US Air Force Weather Agency


25 July-31 July 2001 Citation IconCite this Report

Continuous volcanic tremor was recorded at Satsuma-Iwo-jima during 20 to at least 23 July. A seismometer about 700 m SW of Iwo-dake crater recorded 50-100 earthquakes daily, in comparison to 30-90 earthquakes recorded daily during December 2000 and March 2001. Small amounts of volcanic tremor were also occasionally recorded. The Iwo-jima Branch of the Mishima Village Office reported that ash fell during 19-21 July. Faint ashfall and small volcanic tremor had occurred since December 2000.

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


Bulletin Reports - Index

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.

01/1988 (SEAN 13:01) Small ash plumes; first known since 1935

10/1991 (BGVN 16:10) Continued thermal activity; plume from new crater

01/1999 (BGVN 24:01) April 1998 ashfalls; ash eruptions during July-September

05/1999 (BGVN 24:05) 1997-99 summary; early 1999 eruption deposited 5 cm of ash at crater

07/2001 (BGVN 26:07) Ashfall and volcanic tremor through July 2001

04/2003 (BGVN 28:04) Eruption plumes and ashfall during 24 May-5 June 2002

07/2005 (BGVN 30:07) Small eruptions during March-September 2004 produce ash plumes

07/2012 (BGVN 37:07) Low level tremor and frequent white plumes during October 2010-June 2012

01/2013 (BGVN 38:01) Steam plumes rose to 800 m duing latter half of 2012

07/2014 (BGVN 39:07) Small ash eruption on 4 June 2013

05/2018 (BGVN 43:05) Elevated thermal activity during February-April 2018; one earthquake swarm in March

02/2020 (BGVN 45:02) Single explosion with steam and minor ash, 2 November 2019

05/2020 (BGVN 45:05) Ash explosion on 29 April 2020

11/2020 (BGVN 45:11) Explosion on 6 October 2020 and thermal anomalies in the crater

06/2021 (BGVN 46:06) Thermal activity and gas-and-steam plumes persist during November 2020-April 2021

05/2023 (BGVN 48:05) Intermittent white gas-and-steam plumes, discolored water, and seismicity during May 2021-April 2023




Information is preliminary and subject to change. All times are local (unless otherwise noted)


January 1988 (SEAN 13:01) Citation IconCite this Report

Small ash plumes; first known since 1935

Gray plumes were ejected to 400-500 m above the summit crater of Iwo-dake on 18 January at 0830, 1030, 1640, and 1745. No air or ground shocks were felt by residents. Ash fell on the SE part of the island that evening. When observed from the air on 20 January, the white steam plume was a little larger than usual. A field party at the summit crater 26-28 January measured a fumarole temperature of 788°C, almost the same as in 1985.

Information Contacts: JMA.


October 1991 (BGVN 16:10) Citation IconCite this Report

Continued thermal activity; plume from new crater

"Geologists visited Satsuma-Iwo-jima 7-10 November. Several large fumarole fields exist within and around the 300-m-diameter crater. Accessible fumaroles had temperatures ranging from 100 to > 800°C. Several types of sampling were conducted to geochemically characterize the emissions. GSJ geologists had used a COSPEC to measure a maximum SO2 flux of 500 t/d in May 1990, similar to . . . 15 years previously. In addition to geochemical samples, a portable spectrometer was used to collect spectra of various features to provide ground truth for satellite images of the region. The major summit geomorphological change since last year's visit by GSJ geologists was the formation of a 15 x 30 m pit crater in the SE corner of the main summit crater. Local silica-mine workers first noticed the new pit crater in June or July 1991. A large plume was continuously emitted from the pit crater."

Information Contacts: R. Andres, Michigan Technological Univ; H. Shinohara, R. Symonds, and B. Ritchie, GSJ.


January 1999 (BGVN 24:01) Citation IconCite this Report

April 1998 ashfalls; ash eruptions during July-September

During 25-27 April 1998 residents on Tokaro-Iwo-Jima Island reported minor ashfalls. A field inspection on 4-5 May by members of the Kagoshima Local Meteorological Office disclosed a 5-mm-deep ash deposit around the Iwodake Crater. This was interpreted to record a small-scale ash eruption. Around the time of the visit, earthquakes were at a level higher than usual.

Several to 10 earthquakes per day were recorded during July 1998, similar to levels in March. During 27-29 July, reddish-brown ash clouds were escaping from the summit crater and light ashfalls were reported at the village of Takeshima, 10 km to the E of the summit. Seismicity was lower in August, with generally less than 10 events/day recorded. Several light ashfalls occurred during August. In September, earthquake activity increased to 20-40 events per day, and there were several minor ashfalls.

Information Contacts: Yosihiro Sawada, Earthquake & Tsunami Observation Division, Seismology & Volcanology Dept., Japan Meteorological Agency, 1-3-4 Ote-machi, Chiyoda-ku, Tokyo 100-8122, Japan.


May 1999 (BGVN 24:05) Citation IconCite this Report

1997-99 summary; early 1999 eruption deposited 5 cm of ash at crater

The following summarizes activity at Satsuma-Iwo-jima (also called Tokara-Iwo-jima), an island on the NW rim of Kikai Caldera. Information concerning events in 1997-98 was provided through communications from Yosihiro Sawada, forwarded by Dan Shackelford. More recent information is available at the Japanese Meteorological Agency (JMA) website.

JMA initiated seismic observation at Kikai in September 1997; from the beginning, several volcanic earthquakes were recorded each day. The number of earthquakes increased suddenly in April 1998 to 60-80/day with some days having more than 100 events. Earthquakes were at this high level during a field inspection on 4-5 May 1998. High numbers of earthquakes continued well into June, then gradually waned, before returning to levels seen in March (~10 events/day). Events decreased to <20/day by late June 1998, but increased again to 20-40/day during September, and to more than 60/day in late 1998.

During the inspection in May 1998, JMA staff found a newly deposited ash layer 5 cm thick around the crater, suggesting that an eruption had occurred in late-April or early-May. The Geological Survey of Japan (GSJ) analyzed the ash and concluded that it was composed of silicic and altered lava fragments of Iwo-dake lava (rhyolite). Residents of this volcanic island witnessed ash falls in August and October 1998. In early November GSJ scientists saw intermittent ash emissions from the crater and found ash deposits in the middle of the SE flank.

Volcanic earthquakes occurred 50-100 times/day during January and February 1999, and 90-130 times/day after February. Hypocenters of these earthquakes were located just below Iwo-dake. Island residents observed ash falling on 24 January [and 14 February 1999].

Geophysical activity is monitored by the Sakura-jima Volcano Observatory, Kyoto University, and JMA; geochemical data are maintained by GSJ.

Information Contacts: Yosihiro Sawada, Volcanological Division, Japan Meteorological Agency (JMA), 1-3-4 Ote-machi, Chiyoda-ku, Tokyo 100, Japan (URL: http://www.jma.go.jp/); Volcano Research Center, Earthquake Research Institute (ERI), University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113, Japan (URL: http://www.eri.u-tokyo.ac.jp/VRC/index_E.html); Dan Shackelford, 3124 E. Yorba Linda Blvd., Apt. H-33, Fullerton, CA 92831-2324 USA.


July 2001 (BGVN 26:07) Citation IconCite this Report

Ashfall and volcanic tremor through July 2001

This report covers activity through July 2001. Volcanic tremor was recorded during 20 to 23 July 2001. A seismometer about 700 m SW of Iwo-dake crater recorded 50-110 earthquakes daily, in comparison to 30-90 earthquakes recorded daily during December 2000 and March 2001. The Iwo-jima branch of the Mishima village office reported that ash fell during 19-21 July. A white plume rose to ~ 20 m above the crater. Faint ashfall and weak volcanic tremor had occurred since December 2000.

Information Contacts: Volcano Research Center, Earthquake Research Institute, University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113-0032, Japan (URL: http://www.eri.u-tokyo.ac.jp/VRC/index_E.html).


April 2003 (BGVN 28:04) Citation IconCite this Report

Eruption plumes and ashfall during 24 May-5 June 2002

According to a Japanese Meteorological Agency (JMA) report on 6 June 2002, discolored plumes associated with volcanic tremor had intermittently issued from Kikai since 11 May 2002. The U.S. Air Force Weather Agency reported that plumes emanating from Satsuma-Iwo-jima (an island forming part of the NW caldera rim of Kikai) were visible on satellite imagery during 24-28 May and 1-4 June 2002. The thin plumes drifted to the S, SE, and E during May, and were estimated to be lower than 3 km altitude. Ash was seen from the island of Yaku-shima on the afternoon of 26 May. JMA noted that the number of small volcanic earthquakes increased after 29 May. The JMA report also stated that discolored plumes were observed from Mishima village in the Ryukyu Islands, and that ash fell on residential areas, during 3-5 June 2002.

Information Contacts: Naokuni Uchida, Japan Meteorological Agency (JMA), Fukuoka, Japan (URL: http://www.jma.go.jp/); Volcano Research Center, Earthquake Research Institute, University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113-0032, Japan (URL: http://www.eri.u-tokyo.ac.jp/VRC/index_E.html); Charles Holliday, U.S. Air Force Weather Agency, 106 Peacekeeper Drive, Ste 2NE, Offut AFB, NE 68113-4039, USA (URL: http://www.557weatherwing.af.mil/).


July 2005 (BGVN 30:07) Citation IconCite this Report

Small eruptions during March-September 2004 produce ash plumes

An eruption in 2002 began on 11 May when discolored plumes were noted (BGVN 28:04). Anomalous seismicity began on 14 May 2002, when about 900 events were recorded (table 1). The number of events dropped to very low levels the next day, but then gradually increased to a peak of 967 on the 28th and almost that many on the 29th. During June 2002, seismicity was high on the 2nd (650 events), 3rd (> 300 events), and 8th (~ 240 events). There were also 117 tremor events during the month, 73 of them on the 15th. Plumes and ashfall were reported through 5 June (BGVN 28:04).

Table 1. Summary of seismicity and plume observations at Kikai, May 2002-January 2005. All reported plumes were described as either white (W), light white (LW), grayish white (GW), or gray (G). Data courtesy of JMA.

Month Volcanic Earthquakes Max. plume height (km) (date) Plume Color (number of days, date)
May 2002 6,012 -- --
Jun 2002 1,415 -- --
Jul 2002 198 -- --
Aug 2002 141 -- --
Sep 2002 110 -- --
Oct 2002 144 -- --
Nov 2002 83 0.6 (16) W (11 days)
Dec 2002 102 -- --
Jan 2003 138 0.6 (2, 15) W (30 days)
Feb 2003 182 0.6 (11, 20) W (24 days)
Mar 2003 224 0.7 (4) W (25 days)
Apr 2003 221 0.8 (27) W (21 days)
May 2003 363 0.6 (22, 23, 26) W (19 days)
Jun 2003 366 1.0 (7) W and LW (13 days), GW (7th and 8th)
Jul 2003 94 0.8 (26) W (11 days), GW and G (17th, 26th)
Aug 2003 166 0.8 (23) W, LW (18 days), GW (12th, 16th)
Sep 2003 320 0.8 (1, 5, 19) W (25 days), GW (19th, 22nd)
Oct 2003 166 0.6 (10, 19) W (23 days)
Nov 2003 191 -- --
Dec 2003 186 0.6 (1) W (29 days)
Jan 2004 157 (1-24 Jan) 0.6 (18, 29, 31) W (26 days)
Feb 2004 40 (26-29 Feb) 0.6 (18) W (25 days)
Mar 2004 110 (none 22-25 Mar) 0.7 (29) W, LW (24 days), GW (5th, 24th, 25th)
Apr 2004 199 (1-26 Apr) 0.8 (6) W, LW (27 days)
May 2004 164 (15-31 May) 0.7 (26) W (20 days)
Jun 2004 250 0.7 (30) W (13 days)
Jul 2004 249 0.8 (3) W (14 days)
Aug 2004 219 0.8 (4, 24) W (21 days), GW (13th)
Sep 2004 157 0.7 (25) W (19 days), GW (25th)
Oct 2004 137 0.8 (11) W (25 days)
Nov 2004 173 0.6 (5, 7, 13, 25) W (28 days)
Dec 2004 205 0.7 (6) W (30 days)
Jan 2005 144 0.6 (14, 23) W (29 days)

Activity for the following year consisted of low-level seismicity of less than 200 events per month, and frequent, almost daily, white plumes. Eruptive activity began again on 7-8 June 2003 when 800-1,000 m ash plumes were recorded. Although plumes were not reported, eruptions also occurred during 10-12 June. Additional eruptions were noted by JMA during 7, 14-17, 26, 27, and 30 July, and 12, 13, and 15-18 August 2003. All of the June-August eruptions caused ashfall. The last grayish white eruption plumes in 2003 were seen on 19 and 22 September.

From March to September 2004, Tokyo Volcanic Ash Advisory Center (VAAC) reports indicated a number of small eruptions at Kikai. Three plumes in March 2004 reportedly rose to 1.5 km altitude, but no ash was visible in satellite imagery (table 2). JMA also reported eruptions on those days, but only indicated plumes 700 m high.

Table 2. Date and time of eruptions from Kikai, the direction and altitude of observed plumes, and whether ash was seen on satellite image. Based on information from the Tokyo VAAC.

Date Time Plume Altitude (km) Direction Ash visible on satellite imagery
05 Mar 2004 0922 1.5 N No
24 Mar 2004 1755 1.5 S No
25 Mar 2004 0715 1.5 NW No
01 Jun 2004 1330 -- W Yes
13 Aug 2004 1105 1.2 NW --
25 Sep 2004 0937 1.5 W --

Another plume on 1 June did have ash visible to satellites. This eruption was not included in the JMA observations. Plumes were seen again on 13 August and 25 September, again with JMA only reporting 700-800 m plumes compared to 1.2 and 1.5 km plumes, respectively, in the VAAC advisory. No seismicity was detected during 25 September-5 October 2004, the period following the eruption of a grayish-white plume to 700 m. Data from JMA through January 2005 indicate continuing volcanic earthquakes (less than 10/day in December) and almost daily white plumes as high as 700 m, but generally 400 m or below.

Information Contacts: Japan Meteorological Agency (JMA), Volcanological Division 1-3-4 Ote-machi, Chiyoda-ku, Tokyo 100, Japan (URL: http://www.jma.go.jp/); Tokyo Volcanic Ash Advisory Center, Japan Meteorological Agency (JMA), 1-3-4 Ote-machi, Chiyoda-ku, Tokyo 100, Japan (URL: https://ds.data.jma.go.jp/svd/vaac/data/).


July 2012 (BGVN 37:07) Citation IconCite this Report

Low level tremor and frequent white plumes during October 2010-June 2012

Kikai was the scene of ongoing steaming and modest seismic unrest during October 2010-June 2012. As background, Kikai (also called Satsuma-Iwo-jima and Tokara-Iwo-jima), an island on the NW rim of the submerged Kikai caldera (figure 1), experienced chiefly low-level seismicity between 2002 and 2004 punctuated by stronger earthquakes and tremor, and three small eruptions during May-June 2002, June-August 2003, and March-September 2004 (BGVN 28:04 and 30:07). Almost daily plumes, most of which were white, occurred between late 2002 and at least January 2005 (BGVN 30:07).

Figure (see Caption) Figure 1. Maps showing Kikai caldera and the two associated islands along its rim, Satsuma-Iwo-jima and Tokara-Iwo-jima. The top-right inset map shows the regional extent of the main figure; the lower-left inset map (b) relates to the author's proposed model of pyroclastic flow venting and tsunami generation. Taken from Maeno and Imamura (2007).

Recent monthly reports of volcanic activity from the Japan Meteorological Agency (JMA) translated into English resumed in October 2010. Thus, in this report, we lack JMA reports between January 2005 and September 2010 and only summarize and tabulate activity after October 2010 and as late as June 2012.

In an effort to gather other information, we searched for MODVOLC thermal alerts at Kikai and found none during January 2005 to late September 2012. Only one alert appeared in the past decade. That weak alert occurred on 2 August 2003 at a point along the coast well to the NE of the crater. This was unlikely the result of eruptive causes owing to the location and extended absence of alerts at the crater and dome. Near-source thermal photography (noted by JMA and mentioned below) revealed subtle thermal anomalies suggesting elevated temperatures over parts of the dome.

According to JMA, seismicity was relatively low during October 2010-June 2012. Slight increases occurred during 28-31 October 2010 and on 21 August 2011 (Table 3). White-plumes appeared at Iodake summit crater, and their size remained above background throughout the reporting period (Table 3). An occasional night-time glow was visible with a high-sensitivity camera, during at least January-April 2011, July-August 2011, February 2012, and May-June 2012.

Table 3. Monthly summary of seismicity and plume observations at Kikai during October 2010-June 2012. All reported plumes were described as white. All reported volcanic tremor was of small amplitude and short duration. Seismicity in October 2010 was low (as shown) except for occasional increases on 28, 30 and 31 October. The tremor during February 2011 was the first to occur since February 2010. '-' indicates data not reported. Data courtesy of JMA.

Date Number of tremor events Number of earthquakes ("low" through June 2011) Avg. plume height (maximum height) above Iodake crater (m)
Oct 2010 0 Low -- (--)
Nov 2010 0 Low 200 (300)
Dec 2010 0 Low 100 (300)
Jan 2011 0 Low 100 (300)
Feb 2011 1 Low 100 (300)
Mar 2011 1 Low  
Apr 2011 1 Low  
May 2011 1 Low  
Jun 2011 1 Low  
Jul 2011 8 202  
Aug 2011 0 244  
Sep 2011 0 119  
Oct 2011 2 169  
Nov 2011 0 159 -- (600)
Dec 2011 0 167 -- (300)
Jan 2012 0 209 -- (300)
Feb 2012 0 189 -- (200)
Mar 2012 1 201 -- (400)
Apr 2012 1 126 -- (300)
May 2012 0 212 -- (600)
Jun 2012 1 204 -- (300)

Aerial infrared observations on 14 December 2010 and during November-December 2011 found that the distribution of thermal anomalies in the crater had not changed since previous observations in April 2008 and on 22 December 2009. In addition, according to the Japanese Coast Guard, the summit crater did not visibly change between observations on 22 October 2010 and 19 January 2011. According to a field survey on 26 November 2011, the sulfur-dioxide flux averaged 800 tons per day. In December 2011, discolored water, apparently caused by volcanic activity, was observed near the coast. No remarkable crustal change was observed by GPS during Janurary 2012-June 2012.

The journal Earth, Planets and Space produced an edition in 2002 with 16 articles devoted to Kikai caldera, Satsuma-Iwo-jima, and related topics (Shinohara and others, 2002). A video entitled "Satsuma-Iwojima, Japan" uploaded to Youtube in September 2008 shows a steaming fumarole with bright yellow (sulfur?) incrustations (str4hler, 2008).

References. Maeno, F. and Imamura, F., 2007, Numerical investigations of tsunamis generated by pyroclastic flows from the Kikai caldera, Japan, Geophysical Research Letters, Vol. 34, L23303 (DOI: 10.1029/2007GL031222).

Shinohara, H., Iguchi, M., Hedenquist, J.W., and Koyaguchi, T., 2002, Preface to special volume, Earth, Planets and Space, Vol. 54 (No. 3), pp. 173-174.

str4hler, 2008, [Video] Satsuma-Iwojima, Japan. Accessed 21 September 2012, uploaded to Youtube on 16 September 2008 (URL: http://www.youtube.com/watch?v=jyIhaEQAPlw).

Information Contacts: Japan Meteorological Agency (JMA), Otemachi, 1-3-4, Chiyoda-ku Tokyo 100-8122, Japan (URL: http://www.jma.go.jp/); MODVOLC, 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://modis.higp.hawaii.edu/).


January 2013 (BGVN 38:01) Citation IconCite this Report

Steam plumes rose to 800 m duing latter half of 2012

Kikai is a 17 x 20 km mostly submarine caldera as close as ~40 km from the S margin of the island of Kyushu (see figure 1 in BGVN 37:07; also see Shinohara and others, 2002, for 16 journal articles devoted to this volcano. Maeno, 2008, offers an online overview). A few areas on the caldera rim lie above water (figure 2). Mild-to-moderate emissions have often occurred at the dome called Iwo-dake (alternately spelled Iodake, figure 2). Table 4 summarizes the seismicity and steam plume observations for July-December 2012, an interval of calm, absence of tremor, and low hazard status.

Figure (see Caption) Figure 2. A shaded-relief, contour map of Kikai caldera that labels three islands on the N caldera rim, Satsuma Iwo-jima, Showa Iwo-jima, and Take-shima. Satsuma Iwo-jima contains the highest point of the complex (704 m elevation). On that island, the cones Iwo-dake (a rhyolitic volcano) and Inamura-dake (a basaltic volcano) both reflect post-caldera volcanism focused along or just inside the caldera's wall (the shaded, scalloped line trending NE across the island). The island Showa Iwo-jima emerged during the caldera's last major eruptions, during 1934-1935, starting with floating pumices and including late-stage lava emissions that helped armor the island and allowed it to erode only modestly during the subsequent decades of breaking waves. The caldera floor chiefly resides 300-500 m below sea level but it also contains some post-eruptive cones. From Fukashi Maeno (2008).

Table 4. Monthly summary of seismicity and plume observations at Kikai during July-December 2012. All reported plumes were described as white. Data courtesy of JMA.

Month Earthquakes per month Maximum steam plume height (m above Iwo-dake crater rim)
Jul 2012 238 800
Aug 2012 187 300
Sep 2012 193 500
Oct 2012 219 700
Nov 2012 168 400
Dec 2012 -- --

We last reported on Kikai activity through mid-2012 (BGVN 37:07) covering generally small steam plumes and monthly seismicity of up to ~200 earthquakes per month through June 2012. This report is a compilation of subsequent monthly reports of volcanic activity through December 2012 from Japan Meteorological Agency (JMA) monthly reports. The Alert Level remained constant at Level 2 (on a scale of 1-5: 2 = "Do not approach the crater"), before being downgraded to Level 1 in December 2012.

Between July and September 2012, plume emissions at the Iwo-dake summit crater continued (table 4). Weak incandescence was recorded at night with a high-sensitivity camera on 22 July, 28 August, 6 November and 22-24 November. Seismic activity remained at low levels. No unusual ground deformation was observed in GPS data through December 2012.

An aerial observation conducted by the Japan Maritime Self-Defense Force (JMSDF) on 11 September 2012 revealed white plumes rising from Iwo-dake's summit crater and flanks.

The results of a field survey conducted from 17-20 November 2012 showed no remarkable change in white fumes from Iwo-dake. Infrared images also found that the temperature distribution had remained essentially unchanged. Aerial monitoring conducted by the Japan Coast Guard (JCG) on 25 November 2012 revealed the presence of brown and green discolored water around the eastern coast (similar findings as a previous survey) as well as patterns of steaming similar to those observed during the field survey. SO2 emissions during 17-20 November 2012 were measured to be ~400 tons/day; a previous survey conducted in July 2012 yielded an estimated flux of ~500 tons/day.

References. Shinohara, H., Iguchi, M., Hedenquist, J.W., and Koyaguchi, T., 2002, Preface to special volume, Earth, Planets and Space 54 (3), pp. 173-174.

Maeno, F, 2008, Geology and eruptive history of Kikai Caldera, Earthquake Research Institute, University of Tokyo (URL: http://www.eri.u-tokyo.ac.jp/fmaeno/kikai/kikaicaldera.html); accessed 23 February 2013.

Information Contacts: Japan Meteorological Agency (JMA), Otemachi, 1-3-4, Chiyoda-ku Tokyo 100-8122, Japan (URL: http://www.jma.go.jp/); MODVOLC, 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://modis.higp.hawaii.edu/).


July 2014 (BGVN 39:07) Citation IconCite this Report

Small ash eruption on 4 June 2013

Kikai is a caldera, mostly submerged, which includes several islands (figure 3). Previous reports documented modest seismic activity during October 2010-December 2012, with occasional tremor (through June 2012), minor earthquakes, and diffuse white plumes (BGVN 37:07 and 38:01). Subsequent activity during January 2013-July 2014 included one eruption with intermittent explosions, occasional ash and steam plumes, and sporadic weak seismic tremor.

Figure (see Caption) Figure 3. The subaerial expression of Kikai includes two major islands: Satsuma Iwo-jima (~5.5 km long) and Take-shima (~4.5 km long). Three additional islands are included in the structure: Unose, Asase, and Showa Iwo-jima, of which only Showa Iwo-jima was large enough to include on this topographic map. The red dotted lines correspond to the mostly-submerged Kikai caldera structure. Elevations and bathymetry are indicated by color coding based on the key in meters. Courtesy of the Geological Survey of Japan.

Ash plume on 4 June 2013. During 2013, seismicity from Satsuma Iwo-jima was at background levels and plume activity (vapor plumes that rose 300-900 m above the summit) was limited for most of the year (figure 4). Seismic unrest occurred during 15-26 May but dropped back to normal levels thereafter.

Figure (see Caption) Figure 4. Plots showing multi-year records of measured plume heights (1 and 3) and volcanic earthquakes (2 and 4) during 1 January 1998-3 June 2013 from Satsuma Iwo-jima. Explosive events frequently occurred during 1998-2004 (red arrows) and following a ~8 year hiatus, activity resumed on 3 June 2013. Plume heights are measured in meters above the crater. Note that 1) personnel began observational monitoring on 1 August 1998; 2) video monitoring was installed on 16 November 2002; 3) there were video camera problem during 23 February-21 March 2009; 4) seismic data is incomplete due to problems with monitoring equipment. This record is from a seismic station located less than 1 km from the summit. Courtesy of Japan Meteorological Agency (JMA).

According to the Japan Meteorological Agency (JMA), weak tremor was detected at 0502 on 4 June. At ~0517, an eruption began, with explosions occurring intermittently until 1500. An ash plume drifted W from Satsuma Iwo-jima's summit (figure 5), Iodake (also "Iwo-dake"). As a result, JMA raised the Alert Level from 1 to 2 on a scale of 5. The Tokyo Volcanic Ash Advisory Center (VAAC) issued two advisories on 4 June, although no ash was visible in satellite images. Despite this activity, there were few signs of unrest from the seismic, GPS, and thermal monitoring networks during 3-5 June. JMA released a warning about potentially hazardous conditions within 1 km of the summit and noted that the leeward side of the island could experience ashfall and gas emissions.

Figure (see Caption) Figure 5. Areas at Satsuma Iwo-jima on 4 June 2013 with observed an ash plume (yellow circles) and potential ashfall (white circles). Low-level clouds obscured much of the view, but brown-colored areas in the white clouds were identified as ash. The town of Mishima is located at the cluster of white buildings in the harbor (Nagahama Bay) formed by the Erabuzaki peninsula. Within the harbor and other protected inlets along shore, the water color is orange-brown; this is a persistent feature of the island that results from hydrothermal vents contributing Fe-oxyhydroxides and causing turbidity (Kiyokawa and others, 2012). The look direction in both images is approximately NNW. Courtesy of JMA.

Ashfall from the 4 June 2013 eruption was reported on the flanks of Iodake during field surveys. Deposits were also noted in the village of Mishima, ~3 km WSW of the summit. After 6 June, white plumes rose from the summit as high as 400 m. Sulfur dioxide emissions measured before and after the eruption did not indicate any anomalies; the average flux was 300 tons per day based on measurements from 29 May and 400 tons per day on 9 July 2013.

Aerial surveys and thermal monitoring. Hot springs and other thermal feature have been well-documented and monitored across Satsuma Iwo-jima (figure 6). JMA reported that an aerial survey on 13 June 2013 provided a view of the E flank where a persistently active fumarole appeared to have expanded in size (figure 7). Aerial surveys conducted on 9 July and 25 December 2013 found no major thermal changes on the surface of Iodake; however, elevated temperatures persisted at fumarolic sites (figure 8).

Figure (see Caption) Figure 6. (A) Geologic map of Satsuma Iwo-jima annotated with place names and showing the small islands of Unose (NE), Showa Iwo-jima (NE), and Asase (SE). Lithologies range from rhyolite to basalt; Iodake (also written Iwodake) is dominantly rhyolitic (the Nagahama lava flow is dacitic), Yahazudake is andesitic-to-basaltic, Showa Iwo-jima has a rhyolitic central zone and dacitic breccia zone, and Inamura-dake is basaltic (Maeno and Taniguchi, 2006; Ono and others, 1982). (B) Distribution of fumaroles, hot springs, and diffuse soil gas emissions on Satsuma Iwo-jima and offshore sites. The highest temperatures (~800°C) were mainly restricted to the summit of Iodake, within Oana crater. The black arrow indicates the area where a low-temperature (~100°C) fumarole has been active on the E flank, the location of morphological changes in June 2013. Courtesy of the Geological Survey of Japan.
Figure (see Caption) Figure 7. Aerial survey recording conditions on Satsuma Iwo-jima on 13 June 2013. The scar associated with an active fumarole on the E flank (red circle) was notably larger compared to previous images from December 2012. Courtesy of JMA.
Figure (see Caption) Figure 8. Thermal images (at right) paired with visible light photos of Satsuma Iwo-jima from less than 2 km away taken on 9 July 2013. Visible and thermal images of the N (top) and W flank (bottom). JMA noted that elevated temperatures from the ground surface occurred in areas known for fumarolic activity. These conditions did not change significantly in the months before or after the 4 June 2013 eruption. Courtesy of JMA.

Observations during 2014. JMA reported few changes during January-July 2014 (table 5). White plumes were frequently observed and typically rose 300-800 m above the summit (figure 9). Earthquakes occurred at background levels. Four episodes of tremor occurred in February with a total duration of two minutes. Several field surveys determined that no significant changes were occurring with respect to SO2 flux and thermal emissions. Since December 2013, incandescence from the summit was observed only in January and June 2014.

Table 5.Monthly observations and monitoring data for Satsuma Iwo-jima during December 2013-July 2014. Plume heights were documented and presumably reflect characteristic heights seen above the vent; white plumes were frequently visible. Courtesy of JMA.

Month Plume Height Earthquakes Notes
Dec 2013 400 m 122 Incandescence.
Jan 2014 500 m 153 Incandescence; sulfurous plume visible.
Feb 2014 400 m 180 Four episodes of tremor (2 minutes).
Mar 2014 400 m 173 SO2 flux 700 tons/day.
Apr 2014 500 m 145 --
May 2014 500 m 163 --
Jun 2014 300 m 172 Incandescence; thermal surveys showed no changes to surface temperatures.
Jul 2014 800 m 186 --
Figure (see Caption) Figure 9. Video camera image of Satsuma Iwo-jima at 1500 on 6 January 2014. Steam plumes such as this were frequently observed during January-July 2014 rising 300-800 m above the crater. The camera location was ~3 km W of the summit near the town of Mishima. Courtesy of JMA.

References. Kiyokawa, S., Ninomiya, T., Nagata, T., Oguri, K., Ito, T., Ikehara, M., and Yamaguchi, K.E., 2012, Effects of tides and weather on sedimentation of iron-oxyhydroxides in a shallow-marine hydrothermal environment at Nagahama Bay, Satsuma Iwo-Jima Island, Kagoshima, southwest Japan, Island Arc, 21, 66-78.

Maeno, F. and Taniguchi, H., 2006, Silicic lava dome growth in the 1934–1935 Showa Iwo-jima eruption, Kikai caldera, south of Kyushu, Japan, Bulletin of Volcanology, 68, 673-688.

Ono, K., Soya, T., and Hosono, T., 1982, Geology of the Satsuma-Io-Jima District. Quadrangle Series, Scale 1:50,000, Geological Survey Japan, 80 p.

Information Contacts: Japan Meteorological Agency (JMA), Otemachi, 1-3-4, Chiyoda-ku Tokyo 100-8122, Japan (URL: http://www.jma.go.jp/); Geological Survey of Japan and National Institute of Advanced Industrial Science and Technology (GSJ, AIST) (URL: https://www.gsj.jp/en/index.html, http://www.aist.go.jp/index_en.html); Tokyo Volcanic Ash Advisory Center (VAAC), Tokyo, Japan (URL: http://ds.data.jma.go.jp/svd/vaac/data/).


May 2018 (BGVN 43:05) Citation IconCite this Report

Elevated thermal activity during February-April 2018; one earthquake swarm in March

Heightened activity at Kikai (also known as Satsuma Iwojima) was reported during January 2013-July 2014 (BGVN 39:07), which included one eruption with intermittent explosions, occasional ash and steam plumes, and sporadic weak seismic tremor. Subsequently, seismicity remained at background levels, and plume activity was low. A short-lived period of heightened activity occurred in March 2018, with increased daily plume heights, sulfur dioxide output, and seismicity. Activity returned to background levels by 26 April. This report is based on information supplied by the Japanese Meteorological Agency (JMA).

JMA reported that one small-amplitude short-duration volcanic tremor was detected on 16 March 2018. The number of volcanic earthquakes increased on 19 March, with 93 occurrences, prompting JMA to raise the Alert Level from 1 (active volcano) to 2 (restricted area around the crater), on a 5-level scale. The report noted increased thermal activity since February, with occasional visual observations of incandescence. Plume heights and volcanic earthquakes briefly increased during 22-23 March (figure 10, plot 4).

Figure (see Caption) Figure 10. Plots showing multi-year records of measured plume heights (1 and 4) and volcanic earthquakes (2 and 5) during January 1998-April 2018 from Kikai. Explosive events are indicated by the small volcano icons along the top of plot 1. Plot 3 indicates measured sulfur dioxide in tons/day since 2012. The orange diamonds on plot 4 indicate observations of incandescence. Plume heights are measured in meters above the crater. This record is from a seismic station located less than 1 km from the summit. Courtesy of Japan Meteorological Agency (JMA).

The number of volcanic earthquakes was low during 27 March-2 April. A white plume at the Iwo-dake summit crater rose to 1,800 m above the crater rim in late March (figure 8, plot 4), the highest seen in many years. At the same crater a highly sensitive surveillance camera revealed incandescence at night on 27 and 28 March due to increased thermal activity. No incandescence was observed after 12 April (figure 8, plot 4).

In its report for 20-26 April, JMA noted a white plume at the Iwo-dake summit crater that rose to 700 m above the rim. A field survey conducted on 25 and 26 April confirmed the slight expansion of a thermal anomaly area when compared to 24 and 25 March, but the release amount of sulfur dioxide was slightly less than 300 tons per day (compared with 600 tons on March 24) (figure 8, plot 3).

On 27 April 2018, with volcanic earthquakes being small in number and no observed volcanic tremor, JMA determined that activity had decreased and reduced the warning level from 2 to 1.

Information Contacts: Japan Meteorological Agency (JMA), Otemachi, 1-3-4, Chiyoda-ku Tokyo 100-8122, Japan (URL: http://www.jma.go.jp/).


February 2020 (BGVN 45:02) Citation IconCite this Report

Single explosion with steam and minor ash, 2 November 2019

The 19-km-wide submerged Kikai caldera at the N end of Japan’s Ryukyu Islands was the source of one of the world's largest Holocene eruptions about 6,300 years ago, producing large pyroclastic flows and abundant ashfall. During the last century, however, only intermittent minor ash emissions have characterized activity at Satsuma Iwo Jima island, the larger subaerial fragment of the Kikai caldera; several events have included limited ashfall in communities on nearby islands. The most recent event was a single day of explosions on 4 June 2013 that produced ash plumes and minor ashfall on the flank. A minor episode of increased seismicity and fumarolic activity was reported in late March 2018, but no ash emissions were reported. A new single-day event on 2 November 2019 is described here with information provided by the Japan Meteorological Agency (JMA).

JMA reduced the Alert Level to 1 on 27 April 2018 after a brief increase in seismicity during March 2018 (BGVN 45:05); no significant changes in volcanic activity were observed for the rest of the year. Steam plumes rose from the summit crater to heights around 1,000 m; the highest plume rose 1,800 m. Occasional nighttime incandescence was recorded by high-sensitivity surveillance cameras. SO2 measurements made during site visits in March, April, and May indicated amounts ranging from 300-1,500 tons per day, similar to values from 2017 (400-1,000 tons per day). Infrared imaging devices indicated thermal anomalies from fumarolic activity persisted on the N and W flanks during the three site visits. A field survey of the SW flank on 25 May 2018 confirmed that the crater edge had dropped several meters into the crater since a similar survey in April 2007. Scientists on a 19 December 2018 overflight had observed fumarolic activity.

There were no changes in activity through October 2019. Weak incandescence at night continued to be periodically recorded with the surveillance cameras (figure 11). A brief eruption on 2 November 2019 at 1735 local time produced a gray-white plume that rose slightly over 1,000 m above the Iodake crater rim (figure 12). As a result, JMA raised the Alert Level from 1 to 2. During an overflight the following day, a steam plume rose a few hundred meters above the summit, but no further activity was observed. No clear traces of volcanic ash or other ejecta were found around the summit (figure 13). Infrared imaging also showed no particular changes from previous measurements. Discolored seawater continued to be observed around the base of the island in several locations.

Figure (see Caption) Figure 11. Incandescence at night on 25 October 2019 was observed at Satsuma Iwo Jima (Kikai) with the Iwanogami webcam. Courtesy of JMA (An explanation of volcanic activity at Satsuma Iwo Jima, October 1st year of Reiwa [2019]).
Figure (see Caption) Figure 12. The Iwanogami webcam captured a brief gray-white ash and steam emission rising above the Iodake crater rim on Satsuma Iwo Jima (Kikai) on 2 November 2019 at 1738 local time. The plume rose slightly over 1,000 m before dissipating. Courtesy of JMA (An explanation of volcanic activity at Satsuma Iwo Jima, October 1st year of Reiwa [2019]).
Figure (see Caption) Figure 13. During an overflight of Satsuma Iwo Jima (Kikai) on 3 November 2019 no traces of ash were seen from the previous day’s explosion; only steam plumes rose a few hundred meters above the summit, and discolored water was present in a few places around the shoreline. Courtesy of JMA (An explanation of volcanic activity at Satsuma Iwo Jima, October 1st year of Reiwa [2019]).

For the remainder of November 2019, steam plumes rose up to 1,300 m above the summit, and nighttime incandescence was occasionally observed in the webcam. Seismic activity remained low and there were no additional changes noted through January 2020.

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).


May 2020 (BGVN 45:05) Citation IconCite this Report

Ash explosion on 29 April 2020

The Kikai caldera is located at the N end of Japan’s Ryukyu Islands and has been recently characterized by intermittent ash emissions and limited ashfall in nearby communities. On Satsuma Iwo Jima island, the larger subaerial fragment of the Kikai caldera, there was a single explosion with gas-and-steam and ash emissions on 2 November 2019, accompanied by nighttime incandescence (BGVN 45:02). This report covers volcanism from January 2020 through April 2020 with a single-day eruption occurring on 29 April based on reports from the Japan Meteorological Agency (JMA).

Since the last one-day eruption on 2 November 2019, volcanism at Kikai has been relatively low and primarily consisted of 107-170 earthquakes per month and intermittent white gas-and-steam emissions rising up to 1.3 km above the crater summit. Intermittent weak hotspots were observed at night in the summit in Sentinel-2 thermal satellite imagery and webcams, according to JMA (figures 14 and 15).

Figure (see Caption) Figure 14. Weak thermal hotspots (bright yellow-orange) were observed on 7 January (top) and 6 April 2020 (bottom) at Satsuma Iwo Jima (Kikai). Sentinel-2 satellite images with “Atmospheric penetration” (bands 12, 11, 8A) rendering; courtesy of Sentinel Hub Playground.
Figure (see Caption) Figure 15. Incandescence at night on 10 January 2020 was observed at Satsuma Iwo Jima (Kikai) in the Iodake crater with the Iwanogami webcam. Courtesy of JMA (An explanation of volcanic activity at Satsuma Iwo Jima, January 2nd year of Reiwa [2020]).

Weak incandescence continued in April 2020. JMA reported SO2 measurements during April were 400-2000 tons/day. A brief eruption in the Iodake crater on 29 April 2020 at 0609 generated a gray-white ash plume that rose 1 km above the crater (figure 16). No ashfall or ejecta was observed after the eruption on 29 April.

Figure (see Caption) Figure 16. The Iwanogami webcam captured a brief gray-white ash and steam plume rising above the Iodake crater rim on Satsuma Iwo Jima (Kikai) on 29 April 2020 at 0609 local time. The plume rose 1 km above the crater summit. Courtesy of JMA (An explanation of volcanic activity at Satsuma Iwo Jima, April 2nd year of Reiwa [2020]).

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); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground).


November 2020 (BGVN 45:11) Citation IconCite this Report

Explosion on 6 October 2020 and thermal anomalies in the crater

Kikai is a mostly submarine caldera, 19-km-wide, just S of the Ryukyu Islands of Japan. At the NW rim of the caldera lies the island of Satsuma Iwo Jima (also known as Satsuma-Iojima and Tokara Iojima), and the island’s highest peak, Iodake, a steep stratovolcano. Recent weak ash explosions at Iodake occurred on 2 November 2019 and 29 April 2020 (BGVN 45:02, 45:05). The volcano is monitored by the Japan Meteorological Agency (JMA) and satellite sensors. This report covers the period May-October 2020. During this time, the Alert Level remained at 2 (on a 5-level scale).

Activity at Kikai has been relatively low since the previous eruption on 29 April 2020. During May through October occasional white gas-and-steam emissions rose 0.8-1.3 km above the Iodake crater, the latter of which was recorded in September. Emissions were intermittently accompanied by weak nighttime incandescence, according to JMA (figure 17).

Figure (see Caption) Figure 17. White gas-and-steam emissions rose 1 km above the crater at Satsuma Iwo Jima (Kikai) on 25 May (top) 2020. At night, occasional incandescence could be seen in the Iodake crater, as seen on 29 May (bottom) 2020. Both images taken by the Iwanoue webcam. Courtesy of JMA (An explanation of volcanic activity at Satsuma Iwo Jima, May 2nd year of Reiwa [2020]).

A small eruption at 0757 on 6 October occurred in the NW part of the Iodake crater, which produced a grayish white plume rising 200 m above the crater (figure 18). Faint thermal anomalies were detected in Sentinel-2 thermal satellite imagery in the days just before this eruption (28 September and 3 October) and then after (13 and 23 October), accompanied by gas-and-steam emissions (figures 19 and 20). Nighttime crater incandescence continued to be observed. JMA reported that sulfur dioxide emissions measured 700 tons per day during October, compared to the previous eruption (400-2,000 tons per day in April 2020).

Figure (see Caption) Figure 18. Webcam images of the eruption at Satsuma Iwo Jima (Kikai) on 6 October 2020 that produced an ash plume rising 200 m above the crater (top). Nighttime summit crater incandescence was also observed (bottom). Images were taken by the Iwanoue webcam. Courtesy of JMA (An explanation of volcanic activity at Satsuma Iwo Jima, October 2nd year of Reiwa [2020]).
Figure (see Caption) Figure 19. Weak thermal hotspots (bright yellow-orange) were observed at Satsuma Iwo Jima (Kikai) during late September through October 2020. Sentinel-2 satellite images with “Atmospheric penetration” (bands 12, 11, 8A) rendering; courtesy of Sentinel Hub Playground.
Figure (see Caption) Figure 20. Webcam image of a white gas-and-steam plume rising 1.1 km above the crater at Satsuma Iwo Jima (Kikai) on 27 October 2020. Image was taken by the Iwanoue webcam. Courtesy of JMA (An explanation of volcanic activity at Satsuma Iwo Jima, October 2nd year of Reiwa [2020]).

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); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground).


June 2021 (BGVN 46:06) Citation IconCite this Report

Thermal activity and gas-and-steam plumes persist during November 2020-April 2021

Kikai is located just S of the Ryukyu islands of Japan and contains a 19-km-wide mostly submarine caldera. The island of Satsuma Iwo Jima (also known as Satsuma-Iwo Jima and Tokara Iojima) is located at the NW caldera rim, as well as the island’s highest peak, Iodake. Its previous eruption period occurred on 6 October 2020 and was characterized by an explosion and thermal anomalies in the crater (BGVN 45:11). This report updates information from November 2020 through April 2021 using information from the Japan Meteorological Agency (JMA) and various satellite data. During this time, the Alert Level remained at a 2 (on a 5-level scale), according to JMA.

Activity during the reporting period was relatively low and primarily consisted of faint nighttime incandescence and occasional white gas-and-steam emissions (figure 21). During November 2020 incandescence was observed at night with a high-sensitivity surveillance camera and white gas-and-steam emissions rose to a high of 1 km above the crater on 2 November (figure 22). Sulfur dioxide measurements ranged from 900-1,200 tons/day, which was slightly higher than October (700 tons/day). The number of earthquakes detected during the month was 86, which was slightly lower than the previous month (97). Thermal activity continued in December accompanied by a white gas-and-steam plume that rose 1.2 km above the crater on 23 December (figure 23). The number of earthquakes had increased significantly to 265, as well as the SO2 flux to 800-1,900 tons/day.

Figure (see Caption) Figure 21. Intermittent weak thermal anomalies (yellow-orange) were observed at the summit of Satsuma Iwo Jima (Kikai) on 27 November (top left) 2020, 22 December (top right), 31 January (bottom left) 2021, and 26 April (bottom right). Sentinel-2 satellite images with “Atmospheric penetration” (bands 12, 11, 8A) rendering. Courtesy of Sentinel Hub Playground.
Figure (see Caption) Figure 22. Webcam image of a white gas-and-steam plume rising 1 km above the crater at Satsuma Iwo Jima (Kikai) on 2 November 2020. Image taken by the Iwanoue webcam. Courtesy of JMA (An explanation of volcanic activity at Satsuma Iwo Jima, November 2nd year of Reiwa [2020]).
Figure (see Caption) Figure 23. White gas-and-steam plume rose 1.2 km above the crater at Satsuma Iwo Jima (Kikai) on 23 December (top) 2020. At night, occasional incandescence could be seen in webcam images, as shown on 24 December (bottom). Both images taken by the Iwanoue webcam. Courtesy of JMA (An explanation of volcanic activity at Satsuma Iwo Jima, December 2nd year of Reiwa [2020]).

Similar activity was reported in January 2021 with nighttime incandescence and a gas-and-steam plume that rose to a maximum height of 1.2 km above the Iodake crater that was recorded on 4 January. The SO2 flux was 300-1,800 tons/day. JMA reported some discoloration in the water at the coast near Iodake. There were 144 earthquakes recorded. White gas-and-steam emissions continued in February, rising up to 800 m above the crater on 24 February, as well as nighttime incandescence. The number of earthquakes had decreased slightly to 119 this month. SO2 measurements ranged 900-1,100 tons/day.

During March faint nighttime incandescence and seismicity continued; 145 earthquakes were detected. A white gas-and-steam plume rose to a high of 900 m above the crater on 15 March. The sulfur dioxide flux ranged from 500-1,200 tons/day, which was around a similar range as the previous month. In April, nighttime incandescence and earthquake events persisted; there was a slight increase in the number of earthquakes from 145 to 181. A white gas-and-steam plume rose 1.2 km above the crater on 8 April. Measurements of the SO2 flux were 800-900 tons/day during April.

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); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground).


May 2023 (BGVN 48:05) Citation IconCite this Report

Intermittent white gas-and-steam plumes, discolored water, and seismicity during May 2021-April 2023

Kikai, located just S of the Ryukyu islands of Japan, contains a 19-km-wide mostly submarine caldera. The island of Satsuma Iwo Jima (also known as Satsuma-Iwo Jima and Tokara Iojima) is located at the NW caldera rim, as well as the island’s highest peak, Iodake. Its previous eruption period occurred on 6 October 2020 and was characterized by an explosion and thermal anomalies in the crater (BGVN 45:11). More recent activity has consisted of intermittent thermal activity and gas-and-steam plumes (BGVN 46:06). This report covers similar low-level activity including white gas-and-steam plumes, nighttime incandescence, seismicity, and discolored water during May 2021 through April 2023, using information from the Japan Meteorological Agency (JMA) and various satellite data. During this time, the Alert Level remained at a 2 (on a 5-level scale), according to JMA.

Activity was relatively low throughout the reporting period and has consisted of intermittent white gas-and-steam emissions that rose 200-1,400 m above the Iodake crater and nighttime incandescence was observed at the Iodake crater using a high-sensitivity surveillance camera. Each month, frequent volcanic earthquakes were detected, and sulfur dioxide masses were measured by the University of Tokyo Graduate School of Science, Kyoto University Disaster Prevention Research Institute, Mishima Village, and JMA (table 6).

Table 6. Summary of gas-and-steam plume heights, number of volcanic earthquakes detected, and amount of sulfur dioxide emissions in tons per day (t/d). Courtesy of JMA monthly reports.

Month Max plume height (m) Volcanic earthquakes Sulfur dioxide emissions (t/d)
May 2021 400 162 900-1,300
Jun 2021 800 117 500
Jul 2021 1,400 324 800-1,500
Aug 2021 1,000 235 700-1,000
Sep 2021 800 194 500-1,100
Oct 2021 800 223 600-800
Nov 2021 900 200 400-900
Dec 2021 1,000 161 500-1,800
Jan 2022 1,000 164 600-1,100
Feb 2022 1,000 146 500-1,600
Mar 2022 1,200 171 500-1,200
Apr 2022 1,000 144 600-1,000
May 2022 1,200 126 300-500
Jun 2022 1,000 154 400
Jul 2022 1,300 153 600-1,100
Aug 2022 1,100 109 600-1,500
Sep 2022 1,000 170 900
Oct 2022 800 249 700-1,200
Nov 2022 800 198 800-1,200
Dec 2022 700 116 600-1,500
Jan 2023 800 146 500-1,400
Feb 2023 800 135 600-800
Mar 2023 1,100 94 500-600
Apr 2023 800 82 500-700

Sentinel-2 satellite images show weak thermal anomalies at the Iodake crater on clear weather days, accompanied by white gas-and-steam emissions and occasional discolored water (figure 24). On 17 January 2022 JMA conducted an aerial overflight in cooperation with the Japan Maritime Self-Defense Force’s 1st Air Group, which confirmed a white gas-and-steam plume rising from the Iodake crater (figure 25). They also observed plumes from fumaroles rising from around the crater and on the E, SW, and N slopes. In addition, discolored water was reported near the coast around Iodake, which JMA stated was likely related to volcanic activity (figure 25). Similarly, an overflight taken on 11 January 2023 showed white gas-and-steam emissions rising from the Iodake crater, as well as discolored water that spread E from the coast around the island. On 14 February 2023 white fumaroles and discolored water were also captured during an overflight (figure 26).

Figure (see Caption) Figure 24. Sentinel-2 satellite images of Satsuma Iwo Jima (Kikai) showing sets of visual (true color) and infrared (bands 12, 11, 8a) views on 7 December 2021 (top), 23 October 2022 (middle), and 11 January 2023 (bottom). Courtesy of Copernicus Browser.
Figure (see Caption) Figure 25. Aerial image of Satsuma Iwo Jima (Kikai) showing a white gas-and-steam plume rising above the Iodake crater at 1119 on 17 January 2022. There was also green-yellow discolored water surrounding the coast of Mt. Iodake. Courtesy of JMSDF via JMA.
Figure (see Caption) Figure 26. Aerial image of Satsuma Iwo Jima (Kikai) showing white gas-and-steam plumes rising above the Iodake crater on 14 February 2023. Green-yellow discolored water surrounded Mt. Iodake. Courtesy of JCG.

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 Coast Guard (JCG) Volcano Database, Hydrographic and Oceanographic Department, 3-1-1, Kasumigaseki, Chiyoda-ku, Tokyo 100-8932, Japan (URL: https://www1.kaiho.mlit.go.jp/kaiikiDB/kaiyo30-2.htm); Copernicus Browser, Copernicus Data Space Ecosystem, European Space Agency (URL: https://dataspace.copernicus.eu/browser/).

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.

Eruptive History

There is data available for 26 confirmed Holocene eruptive periods.

[ 2023 Mar 27 - 2023 Jul 31 ] Uncertain Eruption

Episode 1 | Uncertain
2023 Mar 27 - 2023 Jul 31 Evidence from Observations: Reported
 JMA noted that "minor eruptive activity" was recorded during 27 March-3 April and 24-31 July 2023, with white gas-and-steam plumes rising 600-700 m above the crater rim and nightly incandescence at night detected by surveillance cameras. However, no ash or lava effusion was reported. Infrared imagery for at least a year both before and after these reports shows intermittent thermal anomalies from the same N and S parts of the crater where fumarole fields are present around the edges of the dome.

2020 Oct 6 - 2020 Oct 6 Confirmed Eruption VEI: 1

Episode 1 | Eruption
2020 Oct 6 - 2020 Oct 6 Evidence from Observations: Reported

List of 1 Events for Episode 1

Start Date End Date Event Type Event Remarks
2020 Oct 6    - - - - VEI (Explosivity Index) Ash plume 200 m above the crater

2020 Apr 29 - 2020 Apr 29 Confirmed Eruption VEI: 1

Episode 1 | Eruption
2020 Apr 29 - 2020 Apr 29 Evidence from Observations: Reported

List of 1 Events for Episode 1

Start Date End Date Event Type Event Remarks
2020 Apr 29    - - - - VEI (Explosivity Index) Ash plume 1 km above the crater

2019 Nov 2 - 2019 Nov 2 Confirmed Eruption VEI: 2

Episode 1 | Eruption
2019 Nov 2 - 2019 Nov 2 Evidence from Observations: Reported

List of 1 Events for Episode 1

Start Date End Date Event Type Event Remarks
   - - - -    - - - - VEI (Explosivity Index)

2013 Jun 4 - 2013 Jun 4 Confirmed Eruption VEI: 1

Episode 1 | Eruption Iodake
2013 Jun 4 - 2013 Jun 4 Evidence from Observations: Reported

List of 4 Events for Episode 1 at Iodake

Start Date End Date Event Type Event Remarks
2013 Jun 4    - - - - Explosion According to the Japan Meteorological Agency (JMA), weak tremor was detected at 0502 on 4 June. At ~0517, an eruption began, with explosions occurring intermittently until 1500.
2013 Jun 4    - - - - Ash Plume According to the Japan Meteorological Agency (JMA), weak tremor was detected at 0502 on 4 June. At ~0517, an eruption began, with explosions occurring intermittently until 1500. An ash plume drifted W from Satsuma Iwo-jima's summit, Iodake. The Tokyo Volcanic Ash Advisory Center (VAAC) issued two advisories on 4 June, although no ash was visible in satellite images.
2013 Jun 4    - - - - Ashfall Ashfall was reported on the flanks of Iodake during field surveys. Deposits were also noted in the village of Mishima, ~3 km WSW of the summit.
2013 Jun 4    - - - - VEI (Explosivity Index) VEI 1

2004 Mar 5 - 2004 Oct 16 ± 15 days Confirmed Eruption VEI: 2

Episode 1 | Eruption Iwo-dake
2004 Mar 5 - 2004 Oct 16 ± 15 days Evidence from Observations: Reported

List of 3 Events for Episode 1 at Iwo-dake

Start Date End Date Event Type Event Remarks
   - - - -    - - - - Explosion
   - - - -    - - - - Ash
2004 Mar 5    - - - - VEI (Explosivity Index)

2003 Feb 16 (?) ± 15 days - 2003 Oct 16 ± 15 days Confirmed Eruption VEI: 2

Episode 1 | Eruption Iwo-dake
2003 Feb 16 (?) ± 15 days - 2003 Oct 16 ± 15 days Evidence from Observations: Reported

List of 3 Events for Episode 1 at Iwo-dake

Start Date End Date Event Type Event Remarks
   - - - -    - - - - Explosion
   - - - -    - - - - Ash
2003 Feb
(?)
   - - - - VEI (Explosivity Index)

2002 May 11 - 2002 Jul 16 ± 15 days Confirmed Eruption VEI: 2

Episode 1 | Eruption Iwo-dake
2002 May 11 - 2002 Jul 16 ± 15 days Evidence from Observations: Reported

List of 4 Events for Episode 1 at Iwo-dake

Start Date End Date Event Type Event Remarks
   - - - -    - - - - Explosion
   - - - -    - - - - Ash
   - - - -    - - - - Earthquakes (undefined)
2002 May 11    - - - - VEI (Explosivity Index)

2000 Oct 16 ± 15 days - 2001 Dec 16 ± 15 days Confirmed Eruption VEI: 1

Episode 1 | Eruption Iwo-dake
2000 Oct 16 ± 15 days - 2001 Dec 16 ± 15 days Evidence from Observations: Reported

List of 5 Events for Episode 1 at Iwo-dake

Start Date End Date Event Type Event Remarks
   - - - -    - - - - Seismicity (tremor)
   - - - -    - - - - Explosion
   - - - -    - - - - Ash
   - - - -    - - - - Earthquakes (undefined)
2000 Oct    - - - - VEI (Explosivity Index)

2000 Jan 16 ± 15 days - 2000 Mar 16 ± 15 days Confirmed Eruption VEI: 2 (?)

Episode 1 | Eruption Iwo-dake
2000 Jan 16 ± 15 days - 2000 Mar 16 ± 15 days Evidence from Observations: Reported

List of 3 Events for Episode 1 at Iwo-dake

Start Date End Date Event Type Event Remarks
   - - - -    - - - - Explosion
   - - - -    - - - - Ash
2000 Jan    - - - - VEI (Explosivity Index)

1998 Apr 25 - 1999 Aug 16 ± 15 days Confirmed Eruption VEI: 2

Episode 1 | Eruption Iwo-dake
1998 Apr 25 - 1999 Aug 16 ± 15 days Evidence from Observations: Reported

List of 5 Events for Episode 1 at Iwo-dake

Start Date End Date Event Type Event Remarks
   - - - -    - - - - Phreatic activity
   - - - -    - - - - Ash
   - - - -    - - - - Earthquakes (undefined) Before.
   - - - -    - - - - Earthquakes (undefined)
1998 Apr 25    - - - - VEI (Explosivity Index)

1997 Jul 2 ± 182 days Confirmed Eruption VEI: 1 (?)

Episode 1 | Eruption Iwo-dake
1997 Jul 2 ± 182 days - Unknown Evidence from Observations: Reported

List of 3 Events for Episode 1 at Iwo-dake

Start Date End Date Event Type Event Remarks
   - - - -    - - - - Phreatic activity
   - - - -    - - - - Ash
1997    - - - - VEI (Explosivity Index)

1988 Jan 18 - 1988 Jan 18 Confirmed Eruption VEI: 1

Episode 1 | Eruption Iwo-dake
1988 Jan 18 - 1988 Jan 18 Evidence from Observations: Reported

List of 3 Events for Episode 1 at Iwo-dake

Start Date End Date Event Type Event Remarks
   - - - -    - - - - Phreatic activity
   - - - -    - - - - Ash weak or small
1988 Jan 18    - - - - VEI (Explosivity Index)

1934 Sep 19 - 1935 Aug (?) Confirmed Eruption VEI: 2

Episode 1 | Eruption 2 km east of Tokara-Iwo-Jima
1934 Sep 19 - 1935 Aug (?) Evidence from Observations: Reported

List of 10 Events for Episode 1 at 2 km east of Tokara-Iwo-Jima

Start Date End Date Event Type Event Remarks
   - - - -    - - - - Explosion
   - - - -    - - - - Phreatomagmatic
   - - - -    - - - - Lava flow
   - - - -    - - - - Lava dome
   - - - -    - - - - Ash
   - - - -    - - - - Pumice
   - - - -    - - - - Earthquakes (undefined) Before.
   - - - -    - - - - Island
1934 Sep 19    - - - - VEI (Explosivity Index)
1935 Jan 8    - - - - VEI (Explosivity Index)

[ 1914 Feb 13 ] Uncertain Eruption

Episode 1 | Eruption Tokara-Iwo-jima
1914 Feb 13 - Unknown Evidence from Unknown

1430 ± 75 years Confirmed Eruption  

Episode 1 | Eruption Iwo-dake
1430 ± 75 years - Unknown Evidence from Isotopic: 14C (uncalibrated)

List of 1 Events for Episode 1 at Iwo-dake

Start Date End Date Event Type Event Remarks
   - - - -    - - - - Explosion

1340 ± 30 years Confirmed Eruption  

Episode 1 | Eruption Iwo-dake, K-Iw-P2 tephra
1340 ± 30 years - Unknown Evidence from Isotopic: 14C (uncalibrated)

List of 2 Events for Episode 1 at Iwo-dake, K-Iw-P2 tephra

Start Date End Date Event Type Event Remarks
   - - - -    - - - - Explosion
   - - - -    - - - - Tephra

1030 ± 40 years Confirmed Eruption  

Episode 1 | Eruption Iwo-dake, K-Sk-u-4 tephra
1030 ± 40 years - Unknown Evidence from Isotopic: 14C (uncalibrated)

List of 2 Events for Episode 1 at Iwo-dake, K-Sk-u-4 tephra

Start Date End Date Event Type Event Remarks
   - - - -    - - - - Explosion
   - - - -    - - - - Tephra

1010 ± 40 years Confirmed Eruption  

Episode 1 | Eruption Iwo-dake, K-Sk-u-3 tephra
1010 ± 40 years - Unknown Evidence from Isotopic: 14C (uncalibrated)

List of 2 Events for Episode 1 at Iwo-dake, K-Sk-u-3 tephra

Start Date End Date Event Type Event Remarks
   - - - -    - - - - Explosion
   - - - -    - - - - Tephra

0830 ± 40 years Confirmed Eruption  

Episode 1 | Eruption Iwo-dake, K-Iw-P1 tephra
0830 ± 40 years - Unknown Evidence from Isotopic: 14C (uncalibrated)

List of 1 Events for Episode 1 at Iwo-dake, K-Iw-P1 tephra

Start Date End Date Event Type Event Remarks
   - - - -    - - - - Explosion

0750 (?) Confirmed Eruption VEI: 3

Episode 1 | Eruption Iwo-dake
0750 (?) - Unknown Evidence from Correlation: Tephrochronology

List of 4 Events for Episode 1 at Iwo-dake

Start Date End Date Event Type Event Remarks
   - - - -    - - - - Explosion
   - - - -    - - - - Lava flow
   - - - -    - - - - Lava dome
0750
(?)
   - - - - VEI (Explosivity Index)

0390 ± 100 years Confirmed Eruption VEI: 3

Episode 1 | Eruption Iwo-dake
0390 ± 100 years - Unknown Evidence from Isotopic: 14C (uncalibrated)

List of 3 Events for Episode 1 at Iwo-dake

Start Date End Date Event Type Event Remarks
   - - - -    - - - - Explosion
   - - - -    - - - - Lava flow
0390 ± 100 years    - - - - VEI (Explosivity Index)

0280 BCE ± 75 years Confirmed Eruption  

Episode 1 | Eruption Iwo-dake
0280 BCE ± 75 years - Unknown Evidence from Isotopic: 14C (uncalibrated)

List of 2 Events for Episode 1 at Iwo-dake

Start Date End Date Event Type Event Remarks
   - - - -    - - - - Explosion
   - - - -    - - - - Ash

1090 BCE ± 100 years Confirmed Eruption VEI: 2

Episode 1 | Eruption Inamura-dake
1090 BCE ± 100 years - Unknown Evidence from Isotopic: 14C (uncalibrated)

List of 5 Events for Episode 1 at Inamura-dake

Start Date End Date Event Type Event Remarks
   - - - -    - - - - Explosion
   - - - -    - - - - Ash
   - - - -    - - - - Blocks
   - - - -    - - - - Scoria
1090 BCE ± 100 years    - - - - VEI (Explosivity Index)

1830 BCE ± 75 years Confirmed Eruption  

Episode 1 | Eruption Inamura-dake, In-I tephra
1830 BCE ± 75 years - Unknown Evidence from Isotopic: 14C (uncalibrated)

List of 3 Events for Episode 1 at Inamura-dake, In-I tephra

Start Date End Date Event Type Event Remarks
   - - - -    - - - - Explosion
   - - - -    - - - - Ash
   - - - -    - - - - Scoria

2450 BCE ± 840 years Confirmed Eruption  

Episode 1 | Eruption Old Iwo-dake, OIo2a,b tephras
2450 BCE ± 840 years - Unknown Evidence from Correlation: Tephrochronology

List of 3 Events for Episode 1 at Old Iwo-dake, OIo2a,b tephras

Start Date End Date Event Type Event Remarks
   - - - -    - - - - Explosion
   - - - -    - - - - Ash
   - - - -    - - - - Scoria

3250 BCE ± 75 years Confirmed Eruption  

Episode 1 | Eruption Old Iwo-dake, OIo1a,b tephras
3250 BCE ± 75 years - Unknown Evidence from Isotopic: 14C (uncalibrated)

List of 3 Events for Episode 1 at Old Iwo-dake, OIo1a,b tephras

Start Date End Date Event Type Event Remarks
   - - - -    - - - - Explosion
   - - - -    - - - - Pyroclastic flow
   - - - -    - - - - Pumice

4350 BCE (?) Confirmed Eruption VEI: 7

Episode 1 | Eruption Kikai caldera, Akahoya tephra
4350 BCE (?) - Unknown Evidence from Isotopic: 14C (uncalibrated)

List of 8 Events for Episode 1 at Kikai caldera, Akahoya tephra

Start Date End Date Event Type Event Remarks
   - - - -    - - - - Explosion extremely violent or catastrophic
   - - - -    - - - - Pyroclastic flow extremely violent or catastrophic
   - - - -    - - - - Ash
   - - - -    - - - - Caldera Explosion
   - - - -    - - - - Property Damage
   - - - -    - - - - Evacuations
4350 BCE    - - - - Fatalities
4350 BCE
(?)
   - - - - VEI (Explosivity Index)
Deformation History

There is no Deformation History data available for Kikai.

Emission History

There is no Emissions History data available for Kikai.

GVP Map Holdings

Maps are not currently available due to technical issues.

The maps shown below have been scanned from the GVP map archives and include the volcano on this page. Clicking on the small images will load the full 300 dpi map. Very small-scale maps (such as world maps) are not included.

Smithsonian Sample Collections Database

The following 2 samples associated with this volcano can be found in the Smithsonian's NMNH Department of Mineral Sciences collections, and may be availble for research (contact the Rock and Ore Collections Manager). Catalog number links will open a window with more information.

Catalog Number Sample Description Lava Source Collection Date
NMNH 116589-1 Volcanic Ash -- --
NMNH 117451-8 Obsidian Nagahama rhyolite --
External Sites