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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). In: Wunderman, R. (ed.), Bulletin of the Global Volcanism Network, 34:8. Smithsonian Institution. https://doi.org/10.5479/si.GVP.BGVN200908-282080.

Volcano Profile |  Complete Bulletin


Aira

Japan

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.

Table 16. Heights and drift of plumes and their character at Sakura-jima from 3 May 2009 to 29 September 2009. Courtesy of Tokyo Volcanic Ash Advisory Center, pilot reports, and the Japan Meteorological Agency (JMA). Dates are local.

Date Plume altitude/drift Observations
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.

Geologic Background. 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.