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Report on Aira (Japan) — 17 July-23 July 2002

Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 17 July-23 July 2002
Managing Editor: Gari Mayberry

Please cite this report as:

Global Volcanism Program, 2002. Report on Aira (Japan). In: Mayberry, G (ed.), Weekly Volcanic Activity Report, 17 July-23 July 2002. Smithsonian Institution and US Geological Survey.

Volcano Profile |  Weekly Report (17 July-23 July 2002)


Aira

Japan

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

All times are local (unless otherwise noted)


Surface observations from Kagoshima airport revealed that on 22 July an ash cloud from Sakura-jima rose to 2.1-2.4 km a.s.l. Ash was visible extending to the SW on satellite imagery. Ash was also observed on 23 July at an unknown altitude.

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.

Source: US Air Force Weather Agency