Makushin (United States)

Status Normal Eruption 1995 1800m
Stratovolcano (Subduction zone / Intermediate crust (15-25 km))

Makushin

The ice-covered, 1800-m-high Makushin volcano on northern Unalaska Island west of the town of Dutch Harbor is capped by a 2.5-km-wide caldera. The broad, domical structure of Makushin contrasts with the steep-sided profiles of most other Aleutian stratovolcanoes. Much of the volcano was formed during the Pleistocene, but the caldera (which formed about 8000 years ago), Sugarloaf cone on the ENE flank, and a cluster of about a dozen explosion pits and cinder cones at Point Kadin on the WNW flank, are of Holocene age. A broad band of NE-SW-trending satellitic vents cuts across the volcano. The composite Pakushin cone, with multiple summit craters, lies 8 km to the SW of Makushin. Frequent explosive eruptions have occurred during the past 4000 years, sometimes accompanied by pyroclastic flows and surges. Geothermal areas are found in the summit caldera of Makushin and on the SE and eastern flanks of the volcano. They represent the largest and most investigated high-temperature geothermal resources in Alaska. Small-to-moderate explosive eruptions have been recorded at Makushin since 1786.

Makushin volcano is a large, ice-covered volcano on northern Unalaska Island. This March 2, 1987, view from the NE shows a small steam column originating from a vent at the left side of the broad summit and drifting about 3 km to the WNW. A 2-km-wide summit caldera helps give the volcano a broad, dome-like structure that contrasts with the steep-sided profiles of most other Aleutian stratovolcanoes. Minor explosive eruptions have occurred during historical time.

Photo by Harold Wilson (Peninsula Airways), 1987 (courtesy of John Reeder, Alaska Div. Geology Geophysical Surveys).

Last updated 2019-08-04 00:28:03

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