The explosion at 1632 on 31 January (figure 2) deposited a considerable quantity of lapilli [S of the crater]. At 1005 the next day, a strong air shock broke [65 windowpanes at a school in Tarumizu City, about 10 km SE of the crater]. After the l February explosions, [ash] emission from the crater ceased until 6 March [but white vapor emission continued from 2 February until the 6 March explosions]. The number of volcanic earthquakes decreased in February and March.

Figure 2. Summary table of explosions from Minami-dake crater at Sakura-jima, 1977. Data courtesy of JMA.

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.