Explosions from the summit crater of Minami-dake were continuing at the end of 1980. The nine explosions in December brought the year's total to 276, the largest number since 362 were recorded in 1974. The highest December ash cloud rose 1.8 km on the 3rd. Airshocks and tephra fall from the explosions broke [windowpanes] in buildings, automobiles, and aircraft; disrupted traffic; and interrupted electric power on occasion in 1980; but caused no injuries.

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: JMA, Tokyo.