Logo link to homepage

Report on Aira (Japan) — 21 September-27 September 2022


Aira

Smithsonian Institution / US Geological Survey
Weekly Volcanic Activity Report, 21 September-27 September 2022
Managing Editor: Sally Sennert.

Please cite this report as:

Global Volcanism Program, 2022. Report on Aira (Japan) (Sennert, S, ed.). Weekly Volcanic Activity Report, 21 September-27 September 2022. Smithsonian Institution and US Geological Survey.

Weekly Report (21 September-27 September 2022)

Aira

Japan

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

All times are local (unless otherwise noted)


JMA reported that six eruptive events and three explosions at Minamidake Crater (at Aira Caldera’s Sakurajima volcano) were recorded during 19-26 September. Volcanic plumes rose as high as 2.4 km above the crater rim and large blocks were ejected as far as 700 m from the vent. Incandescence at the crater was visible nightly. Sulfur dioxide emissions were somewhat high at 1,900 tons per day on 22 September. Nighttime incandescence at the crater was visible during 2-16 September. A notable eruptive event at 1335 on 23 September generated an ash plume that rose 1.7 km above the crater rim and also drifted down-flank to the SE until 1600. A large amount of ashfall was deposited on the SE flank. 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)