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Saint Helens, Mount

Mount Saint Helens, volcanic peak, 8,363 ft (2,549 m; 9,677 ft/2,950 m before its 1980 eruption) high, SW Wash., historically the most active volcano in the Cascade Range. Dormant since 1857, Mt. St. Helens erupted on May 18, 1980, in one of the largest volcanic explosions in North American history; prior to that event there were a series of earth tremors and steam explosions beginning on Mar. 20, 1980. During the eruption a great portion of the rock facing on north side of the mountain fell, followed by a lateral blast of stone, ash, and poisonous gas that carried debris 17 mi (27 km) and flattened and buried surrounding forest. The disaster took some 65 lives, wiped out substantial populations of elk, deer, bear, and coyote, and destroyed 230 sq mi (600 sq km) of vegetation. A volcanic plume rose 80,000 ft (24,400 m) into the air, blanketing a large area of the NW United States with volcanic ash. The summit of Mt. St. Helens was replaced by a horseshoe-shaped crater 2,460 ft (750 m) deep. A number of smaller eruptions, beginning on May 25 and continuing into 1986, resulted in lava flows that built up a dome in the crater; a new, dome-building eruption began in 2004. The volcano and surrounding area are now part of Mt. St. Helens National Volcanic Monument and have provided biologists with a unique opportunity to observe ecological succession and the reestablishment of natural habitats.

See S. A. Kellar, ed., Mount St. Helens (1982).

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Mount St. Helens

MOUNT ST. HELENS

MOUNT ST. HELENS is a stratovolcanic peak in southwest Washington State. Dormant since 1857, Mount St. Helens erupted on 18 May 1980, after a series of earthquakes below the volcano's peak. It released a mushroom cloud of gases 63,000 feet high and sent a lavalike mixture of glass, gas, and ash down the mountainside at speeds up to a hundred miles per hour, killing sixty people, decimating several native animal populations, and destroying $500 million worth of timber. Economic losses totaled $3 billion. Subsequent minor eruptions occurred on 25 May 1980 and 11 April 1981. In 1982 Mount St. Helens was declared a national volcano monument.

BIBLIOGRAPHY

Caroline D. Harnly, Caroline D., and David A. Tyckoson. Mount St. Helens: An Annotated Bibliography. Metuchen, N.J.: Scarecrow Press, 1984.

CarolynBronstein/c. w.

See alsoDisasters ; Volcanoes ; Washington, State of ; andpicture (overleaf).

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St Helens, Mount

St Helens, Mount Volcanic peak in the Cascade Range, sw Washington state. Dormant since 1857, it erupted on May 18, 1980, killing 60 people. The 2950m (9578ft) summit was reduced to 2560m (8312ft) with a deep horseshoe crater. Two more eruptions occurred in the following two weeks, and it is predicted to erupt again in the early 21st century.

http://www.fs.fed.us/gpnf/mshnvm

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Mount Saint Helens

Mount Saint Helens: see Saint Helens, Mount.

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