Report on Izu-Torishima (Japan) — August 2015
Bulletin of the Global Volcanism Network, vol. 40, no. 8 (August 2015)
Managing Editor: Edward Venzke. Research and preparation by Paul Berger.
Izu-Torishima (Japan) Uncertain ash plume reported by a pilot on 6 July 2013
Please cite this report as:
Global Volcanism Program, 2015. Report on Izu-Torishima (Japan) (Venzke, E., ed.). Bulletin of the Global Volcanism Network, 40:8. Smithsonian Institution. https://doi.org/10.5479/si.GVP.BGVN201508-284090.
30.484°N, 140.303°E; summit elev. 394 m
All times are local (unless otherwise noted)
Vigorous ash plumes from Izu-Torishima (also Torishima) were noted during mid-August 2002 that reached an approximate altitude of 1.2-1.5 km (BGVN 27:07 and 27:10). The volcano apparently remained quiet until 6 July 2013, when a pilot observed an ash plume drifting about 74 km N of the volcano at an altitude of 2.1 km. However, the Tokyo Volcanic Ash Advisory Center did not detect ash in satellite images. The Japan Meteorological Agency (JMA) has no information about this uncertain activity available online.
According to a news account quoting the JMA, a M 6.7 earthquake occurred near Izu-Torishima around 21 April 2013, but there is no evidence this event triggered any explosion.
Geologic Background. The circular, 2.7-km-wide island of Izu-Torishima in the southern Izu Islands is capped by an unvegetated summit cone formed during an eruption in 1939. Fresh lava flows from this eruption form part of the northern coastline of the basaltic-to-dacitic edifice. The volcano is referred to as Izu-Torishima to distinguish it from the several other Japanese island volcanoes called Torishima ("Bird Island"). The main cone is truncated by a 1.5-km-wide caldera that contains two central cones, of which 394-m-high Ioyama is the highest. Historical eruptions have also occurred from flank vents near the north coast and offshore submarine vents. A 6-8 km wide submarine caldera lies immediately to the north.
Information Contacts: Tokyo Volcanic Ash Advisory Center (VAAC), Tokyo, Japan (URL: http://ds.data.jma.go.jp/svd/vaac/data/); Japan Meteorological Agency (JMA), Otemachi, 1-3-4, Chiyoda-ku Tokyo 100-8122, Japan (URL: http://www.jma.go.jp/).