Report on Aira (Japan) — August 2009
Bulletin of the Global Volcanism Network, vol. 34, no. 8 (August 2009)
Managing Editor: Richard Wunderman.
Aira (Japan) May-October 2009, ongoing explosive eruptions
Please cite this report as:
Global Volcanism Program, 2009. Report on Aira (Japan) (Wunderman, R., ed.). Bulletin of the Global Volcanism Network, 34:8. Smithsonian Institution. https://doi.org/10.5479/si.GVP.BGVN200908-282080
31.593°N, 130.657°E; summit elev. 1117 m
All times are local (unless otherwise noted)
Our last reports on Sakura-jima (BGVN 31:06, 32:04, and 34:03) provided maps as well as a chronology of plume observations on this very active stratovolcano for the interval between 7 June 2006 and 24 April 2009. A small pyroclastic flow occurred on 9 April 2009.
The current report continues the chronology of plume observations from 3 May to 3 October 2009 (table 16). Most of the plumes described since 20 March 2007 did not exceed 3 km altitude. The tallest plume recorded in the table, an ash plume on 30 May 2009, rose to about 4.6 km altitude. The 3 October eruption from Minami-dake crater was described as violent. From 1 January through 30 September 2009, no thermal alerts were recorded by MODVOLC.
|03 May-04 May 2009||2.4-3.7 km||Eruptions|
|09 May 2009||2.1-3 km/S||Eruptions|
|12 May 2009||1.8 km/E||Eruptions|
|19 May 2009||2.7 km/SE||Eruptions|
|26 May 2009||2.7 km/NW||Eruptions|
|30 May 2009||4.6 km/SE||Explosion|
|31 May-01 Jun 2009||2.1-3.4 km/S||Eruptions|
|07 Jun 2009||3 km||Eruption|
|09 Jun 2009||2.4 km/N||Eruption|
|12 Jun 2009||1.8 km||--|
|14 Jun-16 Jun 2009||2.4-2.7 km/SE, E||Eruptions|
|24 Jun-30 Jun 2009||2.1-3.4 km/various||Explosions|
|02-04, 06-07 Jul 2009||2.1-2.7 km/various||Explosions|
|08, 10-15 Jul 2009||1.8-3.4 km/NE, E||Explosions|
|15-22 Jul 2009||1.8-2.7/various||Explosions. On 18-19 July airwaves exceeding 100 Pa were observed 3 km SW of the Showa crater. On 19 July, JMA raised the alert level to 3.|
|23, 27 Jul 2009||2.1-3/E, SW||--|
|24-25, 28 Jul 2009||--||Explosions|
|31 Jul-04 Aug 2009||2.1-3.4 km||Explosions|
|05 Aug-10 Aug 2009||1.8-4 km/various||Explosions, eruptions|
|12 Aug-17 Aug 2009||2.1-2.7 km/E, N||Explosions, eruptions|
|19 Aug-25 Aug 2009||2.1-3 km/various||Explosions|
|26-29 Aug, 01 Sep 2009||1.2-3.4 km/various||Explosions|
|02 Sep-08 Sep 2009||1.2-2.7 km/various||Explosions|
|09 Sep-15 Sep 2009||1.5-2.7 km/various||Explosions|
|16, 18-19, 21 Sep 2009||1.5-2.7 km/various||Explosions|
|23, 25, 27-29 Sep 2009||1.8-2.7 km/various||Explosions|
|03 Oct 2009||3 km||Explosions at Minami-dake and Showa|
Late 2009 activity. According to JMA, Sakura-jima exploded violently from the Minami-dake crater at 1645 on 3 October 2009. The resulting Vulcanian plume rose up to 3 km above the crater and ballistics reached as far as 1.7 km away from the crater. This explosive eruption was the first from Minami-dake crater since 22 February 2009. The Showa crater was also active on the night of 2-3 October. Several explosions were observed then, and red hot materials were ejected up to 800 m from the rim.
Geological Summary. The Aira caldera in the northern half of Kagoshima Bay contains the post-caldera Sakurajima volcano, one of Japan's most active. Eruption of the voluminous Ito pyroclastic flow accompanied formation of the 17 x 23 km caldera about 22,000 years ago. The smaller Wakamiko caldera was formed during the early Holocene in the NE corner of the Aira caldera, along with several post-caldera cones. The construction of Sakurajima began about 13,000 years ago on the southern rim of Aira caldera and built an island that was finally joined to the Osumi Peninsula during the major explosive and effusive eruption of 1914. Activity at the Kitadake summit cone ended about 4850 years ago, after which eruptions took place at Minamidake. Frequent historical eruptions, recorded since the 8th century, have deposited ash on Kagoshima, one of Kyushu's largest cities, located across Kagoshima Bay only 8 km from the summit. The largest historical eruption took place during 1471-76.
Information Contacts: Japan Meteorological Agency (JMA), Otemachi, 1-3-4, Chiyoda-ku Tokyo 100-8122, Japan (URL: http://www.jma.go.jp/); Tokyo Volcanic Ash Advisory Center (VAAC), Tokyo, Japan (URL: http://ds.data.jma.go.jp/svd/vaac/data/); MODVOLC, Hawai'i Institute of Geophysics and Planetology (HIGP) Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://modis.higp.hawaii.edu/); Yukio Hayakawa, Gunma University, Faculty of Education, Aramaki 4-2, Maebashi 371-8510, Japan.