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. 758 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.
Geologic Background. 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 and was constructed over the remnants of three dissected stratovolcanoes. It is capped by a 4-km-wide caldera with a central cone, Miharayama, that has been the site of numerous historical eruptions. 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. Historical activity dates back to the 7th century CE. A major eruption in 1986 produced spectacular lava fountains up to 1600 m height and a 16-km-high eruption column; more than 12,000 people were evacuated from the island.
Information Contacts: JMA.