Report on Aira (Japan) — February 1990
Bulletin of the Global Volcanism Network, vol. 15, no. 2 (February 1990)
Managing Editor: Lindsay McClelland.
Aira (Japan) Explosions continue; largest ejects ash to 3,000 m
Please cite this report as:
Global Volcanism Program, 1990. Report on Aira (Japan). In: McClelland, L. (ed.), Bulletin of the Global Volcanism Network, 15:2. Smithsonian Institution. https://doi.org/10.5479/si.GVP.BGVN199002-282080.
31.593°N, 130.657°E; summit elev. 1117 m
All times are local (unless otherwise noted)
The summit crater of Minami-dake remained active, with 14 recorded explosions in both January and February. The largest, at 1003 on 11 January and 1659 on 24 February, ejected ash to 3,000 m above the crater rim, but did not cause any damage. Monthly ash accumulation [at KLMO] was 80 g/m2 in January and 144 g/m2 in February.
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.