Report on Suwanosejima (Japan) — December 1990

Bulletin of the Global Volcanism Network, vol. 15, no. 12 (December 1990)
Managing Editor: Lindsay McClelland

Suwanosejima (Japan) Explosions and ash emissions

Please cite this report as:

Global Volcanism Program, 1990. Report on Suwanosejima (Japan). In: McClelland, L (ed.), Bulletin of the Global Volcanism Network, 15:12. Smithsonian Institution. http://dx.doi.org/10.5479/si.GVP.BGVN199012-282030.

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Suwanosejima

Japan

29.638°N, 129.714°E; summit elev. 796 m

All times are local (unless otherwise noted)


Eruptive activity was weak in the first half of 1990, but explosions became frequent in late July, and activity was most vigorous in October and November. The highest ash cloud (1,500 m) was observed, and ash-related agricultural damage was reported, in late October. Glow from the most active crater . . . was seen at night on 27 October and 10-15 November.

Geologic Background. The 8-km-long, spindle-shaped island of Suwanosejima in the northern Ryukyu Islands consists of an andesitic stratovolcano with two historically active summit craters. The summit of the volcano is truncated by a large breached crater extending to the sea on the east flank that was formed by edifice collapse. Suwanosejima, one of Japan's most frequently active volcanoes, was in a state of intermittent strombolian activity from Otake, the NE summit crater, that began in 1949 and lasted until 1996, after which periods of inactivity lengthened. The largest historical eruption took place in 1813-14, when thick scoria deposits blanketed residential areas, and the SW crater produced two lava flows that reached the western coast. At the end of the eruption the summit of Otake collapsed forming a large debris avalanche and creating the horseshoe-shaped Sakuchi caldera, which extends to the eastern coast. The island remained uninhabited for about 70 years after the 1813-1814 eruption. Lava flows reached the eastern coast of the island in 1884. Only about 50 people live on the island.

Information Contacts: JMA.