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Report on Kikai (Japan) — July 2005

Bulletin of the Global Volcanism Network, vol. 30, no. 7 (July 2005)
Managing Editor: Edward Venzke.

Kikai (Japan) Small eruptions during March-September 2004 produce ash plumes

Please cite this report as:

Global Volcanism Program, 2005. Report on Kikai (Japan). In: Venzke, E (ed.), Bulletin of the Global Volcanism Network, 30:7. Smithsonian Institution. https://doi.org/10.5479/si.GVP.BGVN200507-282060.

Volcano Profile |  Complete Bulletin


Kikai

Japan

30.793°N, 130.305°E; summit elev. 704 m

All times are local (unless otherwise noted)


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.

Geologic Background. 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.

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/).