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Report on Aira (Japan) — June 1987

Scientific Event Alert Network Bulletin, vol. 12, no. 6 (June 1987)
Managing Editor: Lindsay McClelland..

Aira (Japan) Explosions and ash emission continue; gas damages trees

Please cite this report as:

Global Volcanism Program, 1987. Report on Aira (Japan). In: McClelland, L. (ed.), Scientific Event Alert Network Bulletin, 12:6. Smithsonian Institution. https://doi.org/10.5479/si.GVP.SEAN198706-282080.

Volcano Profile |  Complete Bulletin


Aira

Japan

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

All times are local (unless otherwise noted)


An explosion was recorded . . . at 1718 on 14 May, for the first time in 1.5 months. Only two explosions had been recorded since 23 January but quiet ash emission occurred about 20 times a month during those four months. The explosion did not cause any damage. Three explosions were recorded in June, on the 14th, 15th, and 19th. Volcanic gas mixed with rain damaged the island's orange orchard and trees in Kagoshima City . . . on 15 and 16 June. Maximum ash cloud height was 1,500 m on 5 and 13 June. 335 g/m2 of ash accumulated in June at [KLMO]. About 100-400 explosions have been recorded yearly since 1955, with 476 explosions in 1985 and 216 in 1986. Only 18 explosions have been recorded this year, 13 in January.

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.