Volcano World

Redoubt is one of the easternmost stratovolcanoes in the Aleutian arc. Redoubt is about 100 miles southwest of Anchorage in the Lake Clark National Park and Preserve. The volcano began erupting high-silica andesite to dacite about 900,000 years ago. Most eruptions were explosive. About 200,000 years ago the present-day cone of the volcano began to form. This period of activity was accompanied by a shift in composition to basalt and basaltic andesite flows. The cone is capped by thick andesite flows and flanked by pyroclastic debris aprons. Reboubt is covered by glaciers. Lahars and debris flows are common. Redoubt has erupted at least 30 time in the last 10,000 years. The summit crater is filled with ice that feeds a north-flowing glacier. During the 1966 eruption, melting ice produced a jokulhlaup. The four eruptions since 1966 have been moderate to large with VEI=3. The most recent eruptions were in 1989-1990, it was the fourth and most damaging eruption this century. The eruptions caused considerable disruption to air traffic. Debris flows in Drift River valley threatened an oil tanker terminal. Damage and loss of revenue from ash and debris flows totaled about $160 million, making the 1989-1990 eruption the second most costly in the United States history.

Additional photos and a bibliography are available on the Alaska Volcano Observatory homepage.