Report on Izu-Oshima (Japan) — October 1990
Bulletin of the Global Volcanism Network, vol. 15, no. 10 (October 1990)
Managing Editor: Lindsay McClelland.
Izu-Oshima (Japan) Seismicity and steam emission decline
Please cite this report as:
Global Volcanism Program, 1990. Report on Izu-Oshima (Japan) (McClelland, L., ed.). Bulletin of the Global Volcanism Network, 15:10. Smithsonian Institution. https://doi.org/10.5479/si.GVP.BGVN199010-284010
34.724°N, 139.394°E; summit elev. 746 m
All times are local (unless otherwise noted)
Activity decreased, following ash emissions on 4 October . . . . Seismicity and steam emission declined rapidly following the 4 October activity, and no subsequent ash emissions had occurred as of 14 November. No tremor episodes were recorded during October.
Geological Summary. Izu-Oshima volcano in Sagami Bay, east of the Izu Peninsula, is the northernmost of the Izu Islands. The broad, low stratovolcano forms an 11 x 13 km island constructed over the remnants of three older dissected stratovolcanoes. It is capped by a 4-km-wide caldera with a central cone, Miharayama, that has been the site of numerous recorded eruptions datining back to the 7th century CE. More than 40 cones are located within the caldera and along two parallel rift zones trending NNW-SSE. Although it is a dominantly basaltic volcano, strong explosive activity has occurred at intervals of 100-150 years throughout the past few thousand years. A major eruption in 1986 produced spectacular lava fountains up to 1,600 m high and a 16-km-high eruption column; more than 12,000 people were evacuated from the island.
Information Contacts: JMA.