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Mount St. Helens, 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; the range extends from Mount
Garibaldi in British Columbia, Canada, to Lassen Peak in northern California. Geologists call Mount St. Helens a
composite volcano (or stratovolcano), a term for steepsided, 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 form the North American segment of the circum-Pacific "Ring of Fire," a notorious zone that produces
frequent, often destructive, earthquake and volcanic activity.


Some Indians of the Pacific Northwest variously called Mount St. Helens "Louwala-Clough," or "smoking mountain." The
modern name, Mount St. Helens, was given to the volcanic peak in 1792 by Captain George Vancouver of the British
Royal Navy, a seafarer and explorer. He named it in honor of a fellow countryman, Alleyne Fitzherbert, who held the
title Baron St. Helens and who was at the time the British Ambassador to Spain. Vancouver also named three other
volcanoes in the Cascades--Mounts Baker, Hood, and Rainier--for British naval officers.


info from~


http://mountsthelens.com/



Mount St. Helens is the youngest of the major Cascade volcanoes, in the sense that its visible cone was entirely
formed during the past 2,200 years, well after the melting of the last of the Ice Age glaciers about 10,000 years ago.
Mount St. Helens' smooth, symmetrical slopes are little affected by erosion as compared with its older, more glacially
scarred neighbors--Mount Rainier and Mount Adams in Washington, and Mount Hood in Oregon. As geologic studies
progressed and the eruptive history of Mount St. Helens became better known, scientists became increasingly
concerned about possible renewed eruptions. The late William T. Pecora, a former Director of the USGS, was quoted
in a May 10, 1968, newspaper article in the Christian Science Monitor as being "especially worried about snow-covered
Mt. St. Helens."





Mt. ST.Helens  ~



Mt. ST.Helens  ~


On the basis of its youth and its high frequency of eruptions over the past 4,000 years, Crandell, Mullineaux, and their
colleague Meyer Rubin published in February 1975 that Mount St. Helens was the one volcano in the conterminous
United States most likely to reawaken and to erupt "perhaps before the end of this century." This prophetic conclusion
was followed in 1978 by a more detailed report, in which Crandell and Mullineaux elaborated their earlier conclusion
and analyzed, with maps and scenarios, the kinds, magnitudes, and areal extents of potential volcanic hazards that
might be expected from future eruptions of Mount St. Helens. Collectively, these two publications contain one of the
most accurate forecasts of a violent geologic event.





2011 08 05 Mt.ST.Helens 

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