GEOLOGIC HISTORY
The 8 x 16 km Suoh depression appears to be primarily of
tectonic origin, possibly a pull-apart basin. The basin's
margins contain historically active maars and silicic
domes.
Historic Activity:
- On June 25, 1933 a major earthquake occurred,
followed 2 weeks later by severe phreatic eruptions that
ejected great quantities of mud. Pyroclastic surges took
place, and evidence of eruptive activity was observed
over a 5 x 1.5 km area. The eruption formed two large
explosion craters and it was heard 660 km away.
Recent Activity:
- Reports indicate that an eruption occurred in the
Suoh hot-spring field 2 weeks after a major earthquake in
the region (Feb. 15, 1994 a few tens of km SE of Suoh,
magnitude 7.2). Two new 5-m-diameter craters were found
which were erupting hot gas-charged mud to 10 m
height.
Data Sources
- Global Volcanism Network (V. 19, No. 2 and V. 19, No.
5).
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