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View of the 3,374-m summit of Mt. Spurr (background) and 2,309-m Crater Peak (foreground), the site of eruptions in 1953 and 1992. Crater Peak is a satellitic vent perched on the
southern rim of a caldera which formed 10,000-20,000 years ago,
truncating an ancestral stratovolcano. Mt. Spurr is an ice-covered,
silicic-andesite dome complex that has not erupted in historic times.
Crater Peak, which has been active for at least the last 5,000 years, is a basaltic-andesite stratocone with a summit crater approximately 800 m across at its rim. Prior to 1992, it last erupted in 1953. The volcano lies 124 km due west of Anchorage, the principal population center in the state of Alaska. Photo credit: R.G. McGimsey, U.S. Geological Survey, 10/9/91 |