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Report on Bandaisan (Japan) — June 1987

Scientific Event Alert Network Bulletin, vol. 12, no. 6 (June 1987)
Managing Editor: Lindsay McClelland.

Bandaisan (Japan) Earthquake swarm

Please cite this report as:

Global Volcanism Program, 1987. Report on Bandaisan (Japan). In: McClelland, L. (ed.), Scientific Event Alert Network Bulletin, 12:6. Smithsonian Institution. https://doi.org/10.5479/si.GVP.SEAN198706-283160.

Volcano Profile |  Complete Bulletin


Bandaisan

Japan

37.601°N, 140.072°E; summit elev. 1816 m

All times are local (unless otherwise noted)


An earthquake swarm began 16 June, with 155 events recorded that day by the seismograph 2 km SSE of the summit (table 1). Epicenters were mainly concentrated 10 km SW. Seismicity decreased to

Table 1. Daily number of felt earthquakes at Wakamatsu Observatory, 10 km W of the epicentral area of the Bandai swarm, June 1987.

Date Felt Events
16 Jun 1987 7
17 Jun 1987 2
18 Jun 1987 1
21 Jun 1987 2
23 Jun 1987 2

Geologic Background. One of Japan's most noted volcanoes, Bandaisan rises above the north shore of Lake Inawashiro. This complex is formed of several overlapping andesitic stratovolcanoes, the largest of which is Obandai. Kobandai volcano, which collapsed in 1888, was formed about 50,000 years ago. Obandai volcano was constructed within a horseshoe-shaped caldera that formed about 40,000 years when an older volcano collapsed, forming the Okinajima debris avalanche, which traveled to the SW and was accompanied by a plinian explosive eruption. The last magmatic eruption took place more than 25,000 years ago, but four major phreatic eruptions have occurred during the past 5000 years, two of them in historical time, in 806 and 1888. Seen from the south, Bandaisan presents a conical profile, but much of the north side of the volcano is missing as a result of the collapse of Ko-Bandai volcano during the 1888 eruption, in which a debris avalanche buried several villages and formed several large lakes.

Information Contacts: Japan Meteorological Agency (JMA).