The 2,500-km-long Aleutian arc is a chain of large calc-alkaline, strato-volcanoes with impressive calderas. It is responsible for nearly all the historical volcanism of Alaska. The Wrangell Mountains, to the east, include some of world's largest andesitic shield volcanoes, and basaltic lava fields are scattered throughout the western interior and southeastern panhandle of Alaska.

Western record keeping began in 1741 when Vitus Bering landed in Alaska, but these commonly cloud covered volcanoes were only occasionally documented in the following decades. Eruption reporting began with Kasatochi in 1760, four more had erupted by 1768, and there has been a steady increase since.

The most violent Alaskan eruption recorded occurred on June 1912 from Novarupta/Katmai Volcano.  This was one of the world's largest in this century and brought widespread attention to Alaska's many volcanoes.  The 1912 eruption darkened the sky over much of the Northern Hemisphere for several days, depositing a foot of ash on Kodiak.  Novarupta Volcano is located in the Valley of Ten Thousand Smokes, now contained within the Katmai National Park.