The Japan Meteorological Agency (JMA) reported ongoing eruptive activity at Minamidake Crater (Aira Caldera’s Sakurajima volcano) during 24-31 March. Nightly crater incandescence was visible in webcam images. An explosion at 1145 on 25 March generated an ash plume that rose 2.5 km above the crater rim and drifted E. The explosion ejected large blocks 500-700 m from the vent. Another explosion occurred at 2127 on 27 March. On 28 March sulfur dioxide emissions were very high at 3,100 tons per day. Eruptive events at 1213 and 1236 on 25 March and at 1447 on 30 March generated ash plumes that rose 1-1.3 km above the crater rim and drifted E or SE. The Alert Level remained at 3 (on a 5-level scale), and the public was warned to stay 2 km away from both the Minimadake and Showa 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)