Report on Aira (Japan) — October 1996
Bulletin of the Global Volcanism Network, vol. 21, no. 10 (October 1996)
Managing Editor: Richard Wunderman.
Aira (Japan) Seven explosive eruptions in September and October from Minami-dake
Please cite this report as:
Global Volcanism Program, 1996. Report on Aira (Japan) (Wunderman, R., ed.). Bulletin of the Global Volcanism Network, 21:10. Smithsonian Institution.
31.593°N, 130.657°E; summit elev. 1117 m
All times are local (unless otherwise noted)
During September, five explosive eruptions occurred in Minami-dake crater, producing 3 g/m2 of ashfall measured at the Kagoshima Local Meteorological Observatory (KMO), 10 km W of the crater. Totals of 145 earthquakes and 43 tremors were recorded during September at Station B, 2.3 km NW of Minami-dake crater. In contrast, eruptive and seismic activity decreased in October. During October, there were two explosive eruptions in Minami-dake crater with <1 g/m2 ashfall at KMO; 19 earthquakes and one tremor were registered at Station B. The highest plume in October rose 1,300 m above the summit crater.
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 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: Volcanological Division, Japan Meteorological Agency (JMA), 1-3-4 Ote-machi, Chiyoda-ku, Tokyo 100, Japan.