Activity at Minami-dake crater became high during both early and late October. On 28 October, 9 explosive eruptions occurred and significant volcanic ash fell in Kagoshima City. During October, seismic station B (2.3 km NE of Minami-dake crater) recorded 720 earthquakes and 1,206 tremors. On 27-28 October there were seismic swarms. During October the volcano produced 31 eruptions, 23 of them explosive; the highest ash plume, on 28 October, rose 3 km above the summit crater. October ashfall (measured 10 km W at the Kagoshima Meteorological Observatory) was 117 g/m².

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.

Information Contacts: Volcanological Division, Seismological and Volcanological Department, Japan Meteorological Agency (JMA), 1-3-4 Ote-machi, Chiyoda-ku, Tokyo 100 Japan.