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Report on Aira (Japan) — December 1987


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

Aira (Japan) Large explosions break windows; blocks burn cars

Please cite this report as:

Global Volcanism Program, 1987. Report on Aira (Japan) (McClelland, L., ed.). Scientific Event Alert Network Bulletin, 12:12. Smithsonian Institution. https://doi.org/10.5479/si.GVP.SEAN198712-282080



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

All times are local (unless otherwise noted)

Sixteen explosions from the summit crater, some causing damage, were recorded in November. The ash plume reached a maximum height of more than 4 km above the summit on 11 November. Monthly ash accumulation 10 km NW of the summit was 879 g/m2.

Three explosions were particularly strong. The first, at 1536 on 14 November, ejected a large amount of ash to 3.2 km height. Lapilli broke car windshields in the S part of the island. An explosion at 2056 on 17 November was the largest of 1987. An incandescent column reached 1 km, the highest since frequent explosions began in 1955. Large numbers of incandescent blocks were ejected for about 2 hours, burning cars parked at the foot of the volcano. More than 70 instances of volcanic lightning were observed in the eruption cloud. Eight car windshields and 23 solar water heaters were cracked by lapilli. A traffic accident, where a truck lost traction and crashed into a house, was attributed to volcanic ash that had fallen on the road. At 1119 on 28 November an explosion broke eight house windowpanes in Tarumizu city, 10 km SE of the summit. A window in a hotel on the S part of the island was cracked by the air shock.

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.