Report on Akan (Japan) — 15 October-21 October 2008
Smithsonian Institution / US Geological Survey
Weekly Volcanic Activity Report, 15 October-21 October 2008
Managing Editor: Sally Sennert.
Please cite this report as:
Global Volcanism Program, 2008. Report on Akan (Japan) (Sennert, S, ed.). Weekly Volcanic Activity Report, 15 October-21 October 2008. Smithsonian Institution and US Geological Survey.
Akan
Japan
43.384°N, 144.013°E; summit elev. 1499 m
All times are local (unless otherwise noted)
On 17 October, JMA lowered the Alert level for Me-Akan (also called Meakan-dake, which means Meakan Peak) of the Akan volcanic complex from near-crater warning to normal. Seismic tremor was no longer detected after 30 September, and seismicity had remained low after 3 October.
Geological Summary. Akan is a 13 x 24 km caldera located immediately SW of Kussharo caldera in eastern Hokkaido. The elongated, irregular outline of the caldera rim reflects its incremental formation during major explosive eruptions from the early to mid-Pleistocene. There are four post-caldera stratovolcanoes, three at the SW end of the caldera and the other on the NE side. Conical Oakandake was frequently active during the Holocene. The 1-km-wide Nakamachineshiri crater of Meakandake was formed during a major pumice-and-scoria eruption about 13,500 years ago. The Meakandake group, composed of nine overlapping cones E of Lake Akan, has produced mild phreatic eruptions since the beginning of the 19th century. The main cone of Meakandake proper has a triple crater at its summit. Although recorded eruptions at Meakandake have consisted of minor phreatic explosions, four major magmatic eruptions with pyroclastic flows have also occurred during the Holocene.
