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Report on Aira (Japan) — 21 August-27 August 2024


Aira

Smithsonian Institution / US Geological Survey
Weekly Volcanic Activity Report, 21 August-27 August 2024
Managing Editor: Sally Sennert.

Please cite this report as:

Global Volcanism Program, 2024. Report on Aira (Japan) (Sennert, S, ed.). Weekly Volcanic Activity Report, 21 August-27 August 2024. Smithsonian Institution and US Geological Survey.

Weekly Report (21 August-27 August 2024)

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 (Aira Caldera’s Sakurajima volcano) during 19-26 August. Nighttime crater incandescence was visible in webcam images. Eruptive events at 0901 and 0926 on 21 August produced ash plumes that rose 1-1.4 km above the crater rim and drifted N. An explosion at 1457 on 21 August generated an ash plume that rose as high as 2.7 km and drifted N and ejected large blocks 800-1,200 m from the crater rim. Sulfur dioxide emissions were somewhat high that day, averaging 1,800 tons per day. The Alert Level remained at 3 (on a 5-level scale), and the public was warned to stay 1 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)