Mount St. Helens

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Mount St. Helens is a 2551 m (8,365 feet) high volcanic peak in the Cascade Range of southwestern Washington. The volcano had been dormant since 1857, but on 18 May 1980 it erupted, causing one of the largest volcanic explosions in North American history. Before the 1980 eruption Mount St. Helens was 2950 m (9,677 feet) high, but large parts of the mountain were blown away in the blast.

On 20 March 1980, a series of tremors began, cumulating in the eruption two months later. During the eruption a great portion of the rock facing on north side of the mountain collapsed, followed by a lateral blast of stone, ash and poisonous gas that carried debris up to 32 km (20 miles) from the mountain and flattened and buried the surrounding forests. The disaster took some 65 lives, wiped out substantial populations of elk, deer, bear and coyote and destroyed 600 km² (230 sq miles) of vegetation. A volcanic plume rose 18,300 m (60,000 feet) into the air, blanketing a large area of the northwestern United States with volcanic ash.

A smaller eruption occurred a week later, on 25 May and then again on 11 April 1982. The summit of Mount St. Helens was transformed into a horseshoe-shaped crater of 750 m (2,460 feet) deep. The volcano and a 110,000 acre large surrounding area were declared the Mount St. Helens National Volcanic Monument in 1982. The national monument has provided biologists with a unique opportunity to observe ecological succession and the reestablishment of natural habitats.

Mount St. Helens is 3740 km northwest of Washington D.C.