Report on Izu-Oshima (Japan) — July 1990
Bulletin of the Global Volcanism Network, vol. 15, no. 7 (July 1990)
Managing Editor: Lindsay McClelland.
Izu-Oshima (Japan) No volcanic tremor; magnitude 2.2 earthquake on N coast
Please cite this report as:
Global Volcanism Program, 1990. Report on Izu-Oshima (Japan). In: McClelland, L. (ed.), Bulletin of the Global Volcanism Network, 15:7. Smithsonian Institution. https://doi.org/10.5479/si.GVP.BGVN199007-284010.
34.724°N, 139.394°E; summit elev. 758 m
All times are local (unless otherwise noted)
As of 8 August, volcanic tremor has not been recorded since May. A magnitude 2.2 earthquake occurred 30 July on the N coast of the island. The shock was felt (intensity II, JMA scale) at the Oshima Weather Station, and was the first felt earthquake on the island since November 1987.
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.