Kikai

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  • 30.789°N
  • 130.308°E

  • 704 m
    2309 ft

  • 282060
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29 May-4 June 2013

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)

Index of Weekly Reports


2013: May
2004: March | May | August | September
2002: May | June
2001: July

Weekly Reports


29 May-4 June 2013

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

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

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

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

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

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

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


29 May-4 June 2002

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

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)


Index of Monthly 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.

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


Contents of Monthly Reports

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

All times are local (= UTC + 9 hours)

01/1988 (SEAN 13:01) 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 Contact: JMA.

10/1991 (BGVN 16:10) 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.

01/1999 (BGVN 24:01) 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 Contact: Yosihiro Sawada, Earthquake & Tsunami Observation Division, Seismology & Volcanology Dept., Japan Meteorological Agency, 1-3-4 Ote-machi, Chiyoda-ku, Tokyo 100-8122, Japan.

05/1999 (BGVN 24:05) 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 (Email: yagi@gsj.go.jp, URL: http://www.kishou.go.jp); Volcano Research Center, Earthquake Research Institute (ERI), University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113, Japan (Email: nakada@eri.u-tokyo.ac.jp, URL: http://hakone.eri.u-tokyo.ac.jp/vrc/VRC.html); Dan Shackelford, 3124 E. Yorba Linda Blvd., Apt. H-33, Fullerton, CA 92831-2324 USA (Email: danshack@ix.netcom.com).

07/2001 (BGVN 26:07) 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 Contact: Volcano Research Center, Earthquake Research Institute, University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113-0032, Japan (URL: http://hakone.eri.u-tokyo.ac.jp/vrc/VRC.html, Email: nakada@eri.u-tokyo.ac.jp, kaneko@eri.u-tokyo.ac.jp).

04/2003 (BGVN 28:04) 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/, Email: n-uchida@redc-fk.kishou.go.jp); Volcano Research Center, Earthquake Research Institute, University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113-0032, Japan (URL: http://hakone.eri.u-tokyo.ac.jp/vrc/VRC.html, Email: nakada@eri.u-tokyo.ac.jp, kaneko@eri.u-tokyo.ac.jp); Charles Holliday, U.S. Air Force Weather Agency, 106 Peacekeeper Drive, Ste 2NE, Offut AFB, NE 68113-4039, USA (URL: https://afweather.afwa.af.mil/, Email: Charles.Holliday@afwa.af.mil).

07/2005 (BGVN 30:07) 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      Max. plume             Plume Color
                Earthquakes    height (km)        (number of days, date)
                                (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 & LW (13 days)GW (7th and 8th)
    Jul 2003         94        0.8 (26)              W (11 days),GW & 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        0.6 (18, 29, 31)      W (26 days)
                (1-24 Jan)
    Feb 2004         40        0.6 (18)              W (25 days)
                (26-29 Feb)
    Mar 2004        110        0.7 (29)              W, LW (24 days),GW (5th, 24th, 25th)
                (none 22-25 Mar)
    Apr 2004        199        0.8 (6)               W, LW (27 days)
                (1-26 Apr)
    May 2004        164        0.7 (26)              W (20 days)
                (15-31 May)
    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                          Ash visible on
                           Altitude (km)     Direction    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.kishou.go.jp/english/); Tokyo Volcanic Ash Advisory Center, Japan Meteorological Agency (JMA), 1-3-4 Ote-machi, Chiyoda-ku, Tokyo 100, Japan (URL: http://www.jma.go.jp/JMA_HP/jma/jma-eng/jma-center/vaac/, Email: vaac@eqvol.kishou.go.jp).

07/2012 (BGVN 37:07) 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 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       Number of earthquakes     Avg. plume height (maximum height)
(month year)   tremor events   ("low" through June 2011)      above Iodake crater, meters

  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                        <200 (400)
  Apr 2011           1                    Low                        <200 (500)
  May 2011           1                    Low                        <200 (400)
  Jun 2011           1                    Low                        <100 (200)
  Jul 2011           8                    202                        <200 (500)
  Aug 2011           0                    244                        <100 (800)
  Sep 2011           0                    119                        <500 ( - )
  Oct 2011           2                    169                        <200 ( - )
  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/jma/indexe.html); 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://hotspot.higp.hawaii.edu/).

01/2013 (BGVN 38:01) 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 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      Maximum steam plume height
(2012)     per month      (m above Iwo-dake crater rim)

Jul           238                     800
Aug           187                     300
Sep           193                     500
Oct           219                     700
Nov           168                     400
Dec      none reported           none reported

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/jma/indexe.html); 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://hotspot.higp.hawaii.edu/).

Kikai is a mostly submerged, 19-km-wide caldera near the northern end of the Ryukyu Islands south of Kyushu. Kikai was the source of one of the world's largest Holocene eruptions about 6300 years ago. Rhyolitic pyroclastic flows traveled across the sea for a total distance of 100 km to southern Kyushu, and ashfall reached the northern Japanese island of Hokkaido. The eruption devastated southern and central Kyushu, which remained uninhabited for several centuries. Post-caldera eruptions formed Iodake lava dome and Inamuradake scoria cone, as well as submarine lava domes. Historical eruptions have occurred in the 20th century at or near Satsuma-Iojima (also known as Tokara-Iojima), a small 3 x 6 km island forming part of the NW caldera rim. Showa-Iojima lava dome (also known as Iojima-Shinto), a small island 2 km east of Tokara-Iojima, was formed during submarine eruptions in 1934 and 1935. Mild-to-moderate explosive eruptions have occurred during the past few decades from Iodake, a rhyolitic lava dome at the eastern end of Tokara-Iojima.

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

Start Date Stop Date Eruption Certainty VEI Evidence Activity Area or Unit
2013 Jun 4 2013 Jun 4 Confirmed 1 Historical Observations
2004 Mar 5 2004 Oct Confirmed 2 Historical Observations Iwo-dake
2003 Feb (?) 2003 Oct Confirmed 2 Historical Observations Iwo-dake
2002 May 11 2002 Jul Confirmed 2 Historical Observations Iwo-dake
2000 Oct 2001 Dec Confirmed 1 Historical Observations Iwo-dake
2000 Jan 2000 Mar Confirmed 2 Historical Observations Iwo-dake
1998 Apr 25 1999 Aug Confirmed 2 Historical Observations Iwo-dake
1997 Unknown Confirmed 1 Historical Observations Iwo-dake
1988 Jan 18 1988 Jan 18 Confirmed 1 Historical Observations Iwo-dake
1934 Sep 19 1935 Aug (?) Confirmed 2 Historical Observations 2 km east of Tokara-Iwo-Jima
[ 1914 Feb 13 ] [ Unknown ] Uncertain     Tokara-Iwo-jima
1430 ± 75 years Unknown Confirmed   Radiocarbon (uncorrected) Iwo-dake
1340 ± 30 years Unknown Confirmed   Radiocarbon (uncorrected) Iwo-dake, K-Iw-P2 tephra
1030 ± 40 years Unknown Confirmed   Radiocarbon (uncorrected) Iwo-dake, K-Sk-u-4 tephra
1010 ± 40 years Unknown Confirmed   Radiocarbon (uncorrected) Iwo-dake, K-Sk-u-3 tephra
0830 ± 40 years Unknown Confirmed   Radiocarbon (uncorrected) Iwo-dake, K-Iw-P1 tephra
0750 (?) Unknown Confirmed 3 Tephrochronology Iwo-dake
0390 ± 100 years Unknown Confirmed 3 Radiocarbon (uncorrected) Iwo-dake
0280 BCE ± 75 years Unknown Confirmed   Radiocarbon (uncorrected) Iwo-dake
1090 BCE ± 100 years Unknown Confirmed 2 Radiocarbon (uncorrected) Inamura-dake
1830 BCE ± 75 years Unknown Confirmed   Radiocarbon (uncorrected) Inamura-dake, In-I tephra
2450 BCE ± 840 years Unknown Confirmed   Tephrochronology Old Iwo-dake, OIo2a,b tephras
3250 BCE ± 75 years Unknown Confirmed   Radiocarbon (uncorrected) Old Iwo-dake, OIo1a,b tephras
4350 BCE (?) Unknown Confirmed 7 Radiocarbon (uncorrected) Kikai caldera, Akahoya tephra

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
Kikaiga-shima | Tokara-Iwo-jima | Satsuma-Iwo-jima


Cones
Feature Name Feature Type Elevation Latitude Longitude
Asase Cone
Inamuradake
    Inamura-dake
Cone 200 m


Craters
Feature Name Feature Type Elevation Latitude Longitude
Kikai Caldera


Domes
Feature Name Feature Type Elevation Latitude Longitude
Iodake
    Iwo-dake
Dome 704 m 30° 47' 22" N 130° 18' 27" E
Showa Iojima
    Syowa-Iwo-zima
    Shin-Iwo-jima
    Iozima-sinto
    Iwo-jima-shinto
    Showa-Iwo-jima
Dome 26 m


Other
Feature Name Feature Type Elevation Latitude Longitude
Satsuma-Iojima Island - Caldera rim fragment 704 m 30° 47' 35" N 130° 18' 19" E
Kikai is a mostly submerged, 19-km-wide caldera south of Kyushu that was the source of one of the world's largest Holocene eruptions about 6300 years ago. Pyroclastic flows traveled across the sea for a total distance of 100 km and devastated southern and central Kyushu. This view from near the summit of the post-caldera cone Iwo-dake shows the western rim of Kikai caldera forming the peninsula (upper left) behind conical Inamura-dake scoria cone.

Photo by Yasuo Miyabuchi, 1996 (Forestry and Forest Products Research Institute, Kyushu).
Satsuma-Iwo-jima, seen here from the SW, is a complex post-caldera island constructed on the NW margin of Kikai caldera. Iwo-dake (Io-dake) on the right is a lava dome composed of thick rhyolitic lava flows. Rounded Inamura-dake (left) is a scoria cone. Shallow submarine eruptions have also occurred following the formation of the caldera about 6300 years ago.

Photo by Yasuo Miyabuchi, 1996 (Forestry and Forest Products Research Institute, Kyushu).

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.

Hedenquist J W, Aoki M, Shinohara H, 1994. Flux of volatiles and ore-forming metals from the magmatic-hydrothermal system of Satsuma Iwojima volcano. Geology, 22: 585-588.

IAVCEI, 1973-80. Post-Miocene Volcanoes of the World. IAVCEI Data Sheets, Rome: Internatl Assoc Volc Chemistry Earth's Interior..

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.

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

Machida H, 1990. Frequency and magnitude of catastrophic explosive volcanism in the Japan region during the past 130 ka: implications for human occupance of volcanic regions. Geol Soc Aust Symp Proc, 1: 27-36.

Machida H, Arai F, 1981. Late Quaternary large eruptions recorded in distal areas around Japan. IAVCEI Tokyo Mtg Abs, p 214-215.

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

Maeno F, Taniguchi H, 2005. Eruptive history of Satsuma Iwo-jima Island, Kikai caldera, after a 6.5 ka caldera-forming eruption. Bull Volc Soc Japan (Kazan), 50: 71-85 (in Japanese with English abs).

Maeno F, Taniguchi H, 2007. Spatiotemporal evolution of a marine caldera-forming eruption, generating a low-aspect ratio pyroclastic flow, 7.3 ka, Kikai caldera, Japan: implication from near-vent eruptive deposits. J Volc Geotherm Res, 167: 212-238.

Matsushima N, Kazahaya K, Saito G, Shinohara H, 2003. Mass and heat flux of volcanic gas discharging from the summit crater of Iwodake volcano, Satsuma-Iwojima, Japan, during 1996-1999. J Volc Geotherm Res, 126: 285-301.

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/.

Ono K, Soya T, Hosono T, 1982. Geology of the Satsuma-Io-Jima district. Geol Surv Japan, 1:50,000 geol map and text (in Japanese).

Saito G, Kazahaya K, Shinohara H, Stimac J, Kawanabe Y, 2001. Variation of volatile concentration in a magma system of Satsuma-Iwojima volcano deduced from melt inclusion analyses. J Volc Geotherm Res, 108: 11-31.

Ui T, Kobayashi T, 1988. Catastrophic pyroclastic flow eruption at Kikai caldera, 6300 years ago. Kagoshima Internatl Conf Volc Abs, p 396.

Volcano Types

Caldera
Stratovolcano(es)
Lava dome(s)

Tectonic Setting

Subduction zone
Oceanic crust (< 15 km)

Rock Types

Major
Rhyolite
Basalt / Picro-Basalt
Andesite / Basaltic Andesite

Population

Within 5 km
Within 10 km
Within 30 km
Within 100 km
152
152
152
1,002,905

Affiliated Databases

Large Eruptions of Kikai 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.