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Report on Aira (Japan) — May 1983

Scientific Event Alert Network Bulletin, vol. 8, no. 5 (May 1983)
Managing Editor: Lindsay McClelland.

Aira (Japan) Explosions and large plumes; windshields broken

Please cite this report as:

Global Volcanism Program, 1983. Report on Aira (Japan). In: McClelland, L. (ed.), Scientific Event Alert Network Bulletin, 8:5. Smithsonian Institution. https://doi.org/10.5479/si.GVP.SEAN198305-282080.

Volcano Profile |  Complete Bulletin


Aira

Japan

31.593°N, 130.657°E; summit elev. 1117 m

All times are local (unless otherwise noted)


The number of explosions from the summit crater of Minami-dake recorded in May was 22, the same as in April. In the second half of May, most of the explosions ejected lapilli and sent ash and vapor to more than 2 km above the summit. The 4.4-km-high [eruption] column from an explosion at 1320 on 18 May was one of the largest since the eruption began in 1955. On 22 May an explosion at 1237 that sent a column to more than 4 km was followed by 2 hours of continuous ash and vapor ejection. The activity was accompanied by thunder and temporary interruption of electric and telephone service. Ash fell as far as Aburatsu, on the E coast of Kyushu, 70 km E of the volcano. An explosion on 26 May was also accompanied by continuous ash ejection. A large amount of ash fell SSE of the volcano; more than 20 car windshields were broken, and the roof of a primary school cracked.

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: JMA, Tokyo.