Semisopochnoi, the youngest volcanic island in the western Aleutians, made of a shield volcano, a caldera, and several younger stratovolcanoes.. Known eruptions occurred in 1873 and 1987. Four unconfirmed eruptions occurred between 1772 and 1830. The 1987 eruption was explosive with VEI estimated at 2. Photo by Howard Powers, U.S. Geological Survey, ca. 1950.
Sugarloaf Peak (center), on the southeast coast of Semisopochnoi Island, is the suspected source of lava erupted in 1987. Photo by U.S. Navy. Plate 61 from U.S. Geologic Survey Bulletin 1028-O.
Sources of Information:
Coats, R.R., 1959, Geologic reconnaissance of Semisopochnoi Island, Western Aleutian Islands: U.S. Geologic Survey Bulletin 1028-O.
DeLong, S.E., Perfit, M.T., McCulloch, M.T., and Ach, J., 1985, Alaska: Journal of Geology, v. 93, p. 609-618.
Simkin, T., and Siebert, L., 1994, Volcanoes of the World: Geoscience Press, Tucson, Arizona, 349 p.
Wood, C.A., and Kienle, J., 1993, Volcanoes of North America: Cambridge University Press, New York, 354 p.