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Report on Aira (Japan) — April 1986

Scientific Event Alert Network Bulletin, vol. 11, no. 4 (April 1986)
Managing Editor: Lindsay McClelland.

Aira (Japan) Explosions increase in April

Please cite this report as:

Global Volcanism Program, 1986. Report on Aira (Japan). In: McClelland, L. (ed.), Scientific Event Alert Network Bulletin, 11:4. Smithsonian Institution. https://doi.org/10.5479/si.GVP.SEAN198604-282080.

Volcano Profile |  Complete Bulletin


Aira

Japan

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

All times are local (unless otherwise noted)


In April, 55 explosions . . . were recorded. The highest ash cloud, on 25 April, rose 3,200 m above the crater. An air shock from an explosion on 16 April at 0537 broke windows and glass doors 3 km away at the foot of the volcano. Lapilli from an explosion on 23 April at 1207 broke car windshields near the volcano. Typical bursts of microearthquakes occurred on 5, 11, 15, 25, and 26 April.

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.