JMA reported ongoing eruptive activity at Minamidake Crater (Aira Caldera’s Sakurajima volcano) during 27 February-4 March with nighttime crater incandescence. Eruptive events at 0202 on 27 February and at 1429 on 2 March generated ash plumes that rose 1 km above the crater rim and drifted E and rose 1.3 km above the crater rim and drifted SE, respectively. An explosion at 2149 on 2 March produced an ash plume that rose 1 km and drifted S and ejected large blocks 300-500 m from the vent. An explosion at 2026 on 3 March produced an ash plume that rose 1.2 km and drifted SE and ejected large blocks 600-900 m from the vent. Sulfur dioxide emissions were extremely high, averaging 3,700 tons per day on 1 March. The Alert Level remained at 3 (on a 5-level scale), and the public was warned to stay 2 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)