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Mount Helens Active Volcano
US Geologic Survey
Mount St. Helens (2,549 meters - 8,364 feet ((9,677 feet before May 18, 1980)), located in southwestern
Washington about 50 miles northeast of Portland, Oregon, is one of several lofty volcanic peaks that dominate
the Cascade Range of the Pacific Northwest. Geologists call Mount St. Helens a composite volcano (or stratovolcano),
a term for steep-sided, often symmetrical cones constructed of alternating layers of lava flows, ash, and other
volcanic debris. Composite volcanoes tend to erupt explosively and pose considerable danger to nearby life and
property. In contrast, the gently sloping shield volcanoes, such as those in Hawaii, typically erupt nonexplosively,
producing fluid lavas that can flow great distances from the active vents. Although Hawaiian-type eruptions may
destroy property, they rarely cause death or injury. Before 1980, snow-capped, gracefully symmetrical Mount St. Helens
was known as the "Fujiyama of America." Mount St. Helens, other active Cascade volcanoes, and those of Alaska comprise
the North American segment of the circum-Pacific "Ring of Fire," a notorious zone that produces frequent, often
destructive, earthquake and volcanic activity. -- Tilling, et.al., 1990
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