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Report on Aira (Japan) — 22 December-28 December 2021


Aira

Smithsonian Institution / US Geological Survey
Weekly Volcanic Activity Report, 22 December-28 December 2021
Managing Editor: Sally Sennert.

Please cite this report as:

Global Volcanism Program, 2021. Report on Aira (Japan) (Sennert, S, ed.). Weekly Volcanic Activity Report, 22 December-28 December 2021. Smithsonian Institution and US Geological Survey.

Weekly Report (22 December-28 December 2021)

Aira

Japan

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

All times are local (unless otherwise noted)


JMA reported that incandescence from Minamidake Crater (at Aira Caldera’s Sakurajima volcano) was visible at night during 20-27 December. The sulfur dioxide emission rate was 600 tons per day on 20 December. Two eruptive events during 20-24 December produced plumes that rose 1.1 km above the crater rim. Very small eruptive events were detected during 24-27 December. The Alert Level remained at 3 (on a 5-level scale), and residents were warned to stay 2 km away from the 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 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)