Each of the islands in the Aleutian chain is made up of one or more volcanoes. Unimak Island, pictured here in a radar image taken by the Seasat satellite, has many different volcanoes, both young and old. At the top of the image is Westdahl, a large shield volcano that is covered by a glacier; eruptions occurred in 1964-5 and 1978. On the northwest (left) side of Westdahl is Pogromni, a steep-sided stratovolcano. Little is known about Pogromni, and it hasn't erupted in 160 years.
In the middle of the radar image is a broad and low ridge that makes the elliptical rim of Fisher Caldera. This 11 x 18 km wide caldera formed about 9,100 years ago by the eruption of ash flows and the sinking of the original volcanic mountain that was previously there.
At the bottom of the image is a beautiful stratovolcano named Shishaldin. The Aleut Indians who live in the area call the mountain Sisquk, which means, "mountain which points the way when I am lost." Shishaldin is such a tall (2,857 m high) and recognizable volcano that it is a landmark. Shishaldin almost always has a puff of steam coming from its summit crater.
Information Source: C.A. Wood and J. Kienle, editors (1990) Volcanoes of North America: United States and Canada. Cambridge Univ. Press, p 44-49.
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