Mt. St. Helens

by Tikvah's Hope

Title

Mt. St. Helens

Artist

Tikvah's Hope

Medium

Photograph - Photography

Description

A picture of a Mt. St. Helens during the Summer of 2011
Mount St. Helens National Volcanic Monument.

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.
May 18, a Sunday, dawned bright and clear. At 7 a.m. Pacific Daylight Time (PDT), USGS volcanologist David A.
Johnston, who had Saturday-night duty at an observation post about 6 miles north of the volcano, radioed in the
results of some laser-beam measurements he had made moments earlier that morning. Even considering these
measurements, the status of Mount St. Helens' activity that day showed no change from the pattern of the preceding
month. Volcano-monitoring data--seismic, rate of bulge movement, sulfur-dioxide gas emission, and ground
temperature--revealed no unusual changes that could be taken as warning signals for the catastrophe that would
strike about an hour and a half later. About 20 seconds after 8:32 a.m. PDT, apparently in response to a magnitude
5.1 earthquake about 1 mile beneath the volcano, the bulged, unstable north flank of Mount St. Helens suddenly
began to collapse, triggering a rapid and tragic train of events that resulted in widespread devastation and the loss of
57 people, including volcanologist Johnston.

Uploaded

January 10th, 2012

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