The Japan Meteorological Agency (JMA) reported ongoing eruptive activity at Minamidake Crater (Aira Caldera’s Sakurajima volcano) during 28 May-2 June. Very small eruptive events were recorded during 26-28 May. Sulfur dioxide emissions measured during a field survey on 28 May were extremely high, averaging 3,500 tons per day. An explosion at 1537 on 29 May produced an ash plume that rose 1.5 km above the crater rim, going into weather clouds, and ejected large blocks 700 m from the rim. Nighttime crater incandescence was visible during 30 May-2 June. Explosions at 1727 and 2058 on 30 May and at 1610 on 1 June generated ash plumes that rose 3-3.5 km above the crater rim and drifted S and SE and ejected large blocks as far as 1.1 km from the crater rim. An explosion at 2341 on 2 June ejected large blocks as far as 1 km from the crater rim; details about any emissions were unknown. The Alert Level remained at 3 (on a 5-level scale), and the public was warned to be cautious within 2 km of 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)