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Report on Aira (Japan) — September 1987


Scientific Event Alert Network Bulletin, vol. 12, no. 9 (September 1987)
Managing Editor: Lindsay McClelland.

Aira (Japan) Explosions damage windshields, roofs

Please cite this report as:

Global Volcanism Program, 1987. Report on Aira (Japan) (McClelland, L., ed.). Scientific Event Alert Network Bulletin, 12:9. Smithsonian Institution. https://doi.org/10.5479/si.GVP.SEAN198709-282080



31.5772°N, 130.6589°E; summit elev. 1117 m

All times are local (unless otherwise noted)

Eighteen explosions . . . were recorded in September. Monthly ash accumulation at [KLMO] reached 1,093 g/m2, the largest value for September ash accumulation since measurement began in 1969. An explosion at 0612 on 24 September generated a loud sound and strong air shock. Lapilli broke or damaged seven car windshields, a house windowpane, 14 rooftop solar water heaters, and five roof tiles. A large amount of lapilli fell on the road from WNW to NW of the summit. The largest clast was 10-20 cm long. Ash emission following the explosion continued until 1330, resulting in heavy ash accumulation.

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 caldera, along with several post-caldera cones. The construction of Sakurajima began about 13,000 years ago on the southern rim and built an island that was joined to the Osumi Peninsula during the major explosive and effusive eruption of 1914. Activity at the Kitadake summit cone ended about 4,850 years ago, after which eruptions took place at Minamidake. Frequent eruptions since the 8th century have deposited ash on the city of Kagoshima, located across Kagoshima Bay only 8 km from the summit. The largest recorded eruption took place during 1471-76.

Information Contacts: JMA.