BackgroundThe Pleistocene-to-Holocene Mount Edgecumbe volcanic field covers about 260 sq km of Kruzov Island west of Sitka in the SE panhandle of Alaska. The basaltic-to-dacitic field is dominated by the large composite cones of Mount Edgecumbe, Crater Ridge, and Shell Mountain and has an unusual tectonic setting only 16 km east of the Queen Charlotte-Fairweather transform fault separating the North American and Pacific plates. Mount Edgecumbe, a 970-m-high stratovolcano with a well-defined crater, is the largest volcano of the Edgecumbe field. Crater Ridge is truncated by a 1.6-km-wide, 240-m-deep caldera. These and other vents of the volcanic field are oriented along a SW-NE line. Volcanic activity originated about 600,000 years ago along fissures cutting Kruzof Island. A series of major silicic explosive eruptions took place about 9000-13,000 radiocarbon years ago. The latest dated eruptions were phreatomagmatic explosions during the mid-Holocene, and all postglacial activity has been pyroclastic. Reports of historical eruptions of Mount Edgecumbe are unsubstantiated.
Smithsonian / GVP volcano information
See also: Sentinel hub | Landsat 8