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Narrative of Mount St. Helens By human standards--especially to those nearby--the eruption seemed to be of apocalyptic proportions. The crown and heart of a whole mountain were blasted away, and the entire surrounding landscape was changed. The energy released is estimated at many megatons--thousands of times stronger than the Hiroshima bomb. The eruption claimed 57 human lives, thousands of deer, elk, and bears, and countless smaller animals. It destroyed 232 square miles of forest, numerous structures, roads, and machines, and partially buried communities up to a thousand miles away. Yet, the losses could have been much greater, especially if it had occurred at a busier time or if the blast had been directed toward the Portland/Vancouver metropolitan area, only 45 miles away to the southwest, or if the wind had been blowing toward the southwest.
The eruption of Mount St. Helens, in Washington State, on May 18, 1980, must surely rank as the most intensively studied volcanic event (Lipman & Mullineaux, 1982). Damage to forests cost $450 million; to property, $103 million; to agriculture, $39 million. Clean-up cost was an additional $363 million, but most of these sums were absorbed by the Federal Government without a significant impact on the national economy. For an extended discussion of Mount St. Helens, see http://vulcan.wr.usgs.gov/ljt_slideset.html [ Narrative of Mt. St. Helens: page 1 / page 2 / page 3 / page 4 / page 5 ] |
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As we "step back"
from Mount St. Helens and look at the entire American Northwest, we see the Cascade
Mountains dotted with large symmetrical peaks surrounded by both young and old volcanic
deposits from northern California to southern Canada. Like Mount Rainier, some of these
are near large centers of population. What might happen if one of these giants should
awaken from its torpid or dormant state? Photo: Courtesy of NGDC/NOAA.
Physical
and Monetary Effects of the 1980 Mount St. Helens Eruption The
effects of the eruption were disastrous. The once well-proportioned 9,671 foot peak now
has a rim that reaches a reported 8,400 feet at its highest point. The north flank,
opening to the crater, is now at about 4,400 feet above sea level. Nearly a cubic mile of
the mountain was ejected into the atmosphere or carried away in mud flows. The blast
destroyed many square miles of forest, killing both vegetation and wildlife. More than
sixty people have been listed as killed or missing. Three billion board feet of timber,
valued at approximately $400 million, were damaged or destroyed (U.S. Senate Hearings,
1980; pp. 151). One hundred and sixty-nine lakes and more than 3,000 miles of streams were
either marginally damaged or destroyed (U.S. Senate Hearings 1980, 139). In total, after
the first two major eruptions (May 18 and May 25) it was estimated that damages totaled
more than $1.8 billion in property and crops: this included damages in the vicinity of the
volcano as well as those areas exposed to the ash fall. Photo:
Courtesy of NGDC/NOAA.