Geologic Background:
The massive Emmons Lake stratovolcano, located
north of Volcano Bay, SW of Pavlof volcano, is truncated
by one of the largest calderas of the Aleutian arc. The
11 x 18 km caldera, which contains a narrow elongated
lake at its SW end, was formed during two late-Quaternary
rhyolitic eruptions that produced extensive ashflow
tuffs. Mount Emmons, Mount Hague, and Double Crater are
post-caldera cones of dominantly basaltic composition
that were constructed along the SW-NE trend of the
elongated caldera, which is up to 1150 m deep. Some young
Holocene flows have moved through a gap in the southern
caldera rim to within 1 km of the Pacific Ocean. A large
fumarolic area is located on the south side of Mount
Hague, and the only reported historical activity from
Emmons Lake volcano was the emission of steam plumes from
Mt. Hague in 1990 and 1991.
Historic Activity:
Recent Activity:
- A large fumarolic area occurs on the south side of
Mount Hague (on caldera floor), which is near the eastern
margin of the caldera.
Data Sources:
- Smithsonian's Global Volcanism Network (V. 15, No.
9).
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