Okmok 400 yBP

Start: 1750 [1]

Stop: 300 yBP [1]

Event Type: Not an eruption

Event Characteristics:
  • Lahar, debris-flow, or mudflow [1]
  • Caldera lake change [1]

Description: From Beget and others (2005): "There is evidence that a lake filled the caldera to a depth of 150 meters over a period of several hundred years. The caldera lake drained catastrophically after failure of part of the caldera rim. The resultant flood caused deep erosion of the landscape on the north side of the volcano (Wolfe, 2001). Lahar deposits are present at low elevations in many of the stream valleys draining the volcano, and can be traced up to 12 kilometers down valley from the caldera rim. At most sites only a single lahar deposit is exposed, but at least three lahars, each more than 1 meter thick, occur in sea cliffs near the mouth of Ginger Creek on the west flank of the volcano, and are exposed intermittently for more than 2 kilometers along the beach. Radiocarbon dates suggest these lahars were emplaced 300 to 400 years ago."

References Cited

[1] Preliminary volcano-hazard assessment for Okmok Volcano, Umnak Island, Alaska, 2005

Beget, J.E., Larsen, J.F., Neal, C.A., Nye, C.J., and Schaefer, J.R., 2005, Preliminary volcano-hazard assessment for Okmok Volcano, Umnak Island, Alaska: Alaska Division of Geological & Geophysical Surveys Report of Investigation 2004-3, 32 p., 1 sheet, scale 1:150,000.
map sheet 53.2 MB

Complete Eruption References

Preliminary volcano-hazard assessment for Okmok Volcano, Umnak Island, Alaska, 2005

Beget, J.E., Larsen, J.F., Neal, C.A., Nye, C.J., and Schaefer, J.R., 2005, Preliminary volcano-hazard assessment for Okmok Volcano, Umnak Island, Alaska: Alaska Division of Geological & Geophysical Surveys Report of Investigation 2004-3, 32 p., 1 sheet, scale 1:150,000.
full text of report 3.4 MB
map sheet 53.2 MB
× Instrument data