JMA reported that nighttime incandescence at Minamidake Crater (at Aira Caldera’s Sakurajima volcano) was visible during 28 June-4 July. Two eruptive events and one explosion produced plumes that rose as high as 1.6 km above the crater rim. An explosion, the first recorded since 28 January, was detected at 1221 on 27 June and ejected tephra 600-900 m above the crater rim. The sulfur dioxide rate was 800 tons per day on 30 June. 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)