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Report on Aira (Japan) — 22 March-28 March 2023


Aira

Smithsonian Institution / US Geological Survey
Weekly Volcanic Activity Report, 22 March-28 March 2023
Managing Editor: Sally Sennert.

Please cite this report as:

Global Volcanism Program, 2023. Report on Aira (Japan) (Sennert, S, ed.). Weekly Volcanic Activity Report, 22 March-28 March 2023. Smithsonian Institution and US Geological Survey.

Weekly Report (22 March-28 March 2023)

Aira

Japan

31.5772°N, 130.6589°E; summit elev. 1117 m

All times are local (unless otherwise noted)


JMA reported ongoing eruptive activity at Minamidake Crater (at Aira Caldera’s Sakurajima volcano) during 20-27 March, with crater incandescence visible nightly. Two explosions recorded on 21 and 22 March produced ash plumes that rose 1.2 km above the crater rim and ejected large blocks 1-1.3 km from the vent. Two eruptive events during 24-27 March produced volcanic plumes that rose 1.1 km. The Alert Level remained at 3 (on a 5-level scale), and residents were warned to stay 2 km away from both craters.

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 caldera, along with several post-caldera cones. The construction of Sakurajima began about 13,000 years ago on the southern rim and built an island that was joined to the Osumi Peninsula during the major explosive and effusive eruption of 1914. Activity at the Kitadake summit cone ended about 4,850 years ago, after which eruptions took place at Minamidake. Frequent eruptions since the 8th century have deposited ash on the city of Kagoshima, located across Kagoshima Bay only 8 km from the summit. The largest recorded eruption took place during 1471-76.

Source: Japan Meteorological Agency (JMA)