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Report on Aira (Japan) — August 1990

Bulletin of the Global Volcanism Network, vol. 15, no. 8 (August 1990)
Managing Editor: Lindsay McClelland.

Aira (Japan) Continued vigorous explosions

Please cite this report as:

Global Volcanism Program, 1990. Report on Aira (Japan). In: McClelland, L (ed.), Bulletin of the Global Volcanism Network, 15:8. Smithsonian Institution. https://doi.org/10.5479/si.GVP.BGVN199008-282080.

Volcano Profile |  Complete Bulletin


Aira

Japan

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

All times are local (unless otherwise noted)


During August, 20 explosions (with a maximum ash cloud height of 3,000 m on the 23rd) were recorded . . . . A monthly total of 2,307 g/m2 of ash was deposited 10 km W of the crater.

On 28 August at 0230, a large explosion ejected many blocks to the middle flank of the volcano. Twenty lightning flashes were seen in the volcanic cloud. Two car windshields were broken by lapilli 4 km from the summit and two blocks, roughly 60 cm across, fell 3 km S of the summit. No eruption-related damage had been reported since 1 May.

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.