Report on Izu-Oshima (Japan) — October 1995
Bulletin of the Global Volcanism Network, vol. 20, no. 10 (October 1995)
Managing Editor: Richard Wunderman.
Izu-Oshima (Japan) Minor tremor and 48 earthquakes
Please cite this report as:
Global Volcanism Program, 1995. Report on Izu-Oshima (Japan) (Wunderman, R., ed.). Bulletin of the Global Volcanism Network, 20:10. Smithsonian Institution.
34.724°N, 139.394°E; summit elev. 758 m
All times are local (unless otherwise noted)
On 4 October, local instruments recorded volcanic tremor of short duration and small amplitude. Throughout the month a significant but undisclosed number of earthquakes occurred in the adjacent N and W coastal areas. During October there were 48 earthquakes beneath the cone.
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: Volcanological Division, Seismological and Volcanological Department, Japan Meteorological Agency (JMA), 1-3-4 Ote-machi, Chiyoda-ku, Tokyo 100 Japan.