Geologic Background:
Augustine Island, an 8 by 11 km island in lower
Cook Inlet, is composed almost entirely of the deposits
of Augustine Volcano. The volcano consists of a central
dome and lava flow complex, surrounded by pyroclastic
debris.
Historic Activity:
- Eruptions occurred in 1812, 1883, 1935, 1963-1964,
and 1976.
Recent Activity:
- From July 1985-March 1986, increased seismicity and
minor ash emission occurred.
- Beginning in March 1986 strong explosions sent ash
clouds as high as 14.5 km and pyroclastic flows to the
sea.
- During April 1986 a new lava dome began to form in
the summit crater. From May to June 1986, activity
subsided. During July and August 1986, slow lava dome
growth and pyroclastic flows occurred.
- Continuous steam emission through July
1988.
Data Sources:
- Smithsonian's SEAN Bulletin (V. 11, No. 2 to V. 11,
No. 8; V. 13, No. 7; and V. 14, No. 9).
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