Report on Aira (Japan) — January 1989
Scientific Event Alert Network Bulletin, vol. 14, no. 1 (January 1989)
Managing Editor: Lindsay McClelland.
Aira (Japan) Explosions and ashfall decrease
Please cite this report as:
Global Volcanism Program, 1989. Report on Aira (Japan) (McClelland, L., ed.). Scientific Event Alert Network Bulletin, 14:1. Smithsonian Institution. https://doi.org/10.5479/si.GVP.SEAN198901-282080.
31.593°N, 130.657°E; summit elev. 1117 m
All times are local (unless otherwise noted)
A total of 155 explosions were recorded in 1988, compared to 106 in 1987. Yearly ash accumulation at [KLMO] was 6,503 g/m2, an increase from 1987. No explosions were recorded . . . during December, but two occurred in January, at 0944 on the 26th and 1758 on the 28th. The second event, accompanied by a loud explosive sound and strong air shock, ejected an ash plume to 2000 m above the crater. Windshields of eight cars on the S part of the island were broken by lapilli from the explosion. Only 4 g/m2 of ash accumulated at [KLMO] during [December]. A seismometer 2.3 km NW of the volcano registered 28,283 earthquakes in 1988.
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.