Mount St. Helen

Mount St. Helen

Mount St. Helen is a volcano located along the Cascade range which is a
volcano chain stretching from Northern California to British Colombia. It now
stands at a height of 8,364 feet above sea level.
Mount St. Helen was on of the smaller eruptions of five major ones in
Washington State. It’s elevation before the eruption was 9,677 feet high.
On March 29, 1980 after a period of one-hundred and twenty-three years
of inactivity a earthquake under the volcano quaked, and seven days later a
pheartic (steam) explosions began.
As magma pushed up from beneath the earth’s surface, the north side of
the mountain developed a bulge. Angle and slope-distance measurements
indicating that the bulge was growing at a rate of 1.5 feet per day (Lyn Topinka
Page 2). By May 17 the volcano’s north-side had been pushed upward and
outward 450 feet (Lynn Topinka Page 2).
On May 18,1980 at 8:32 a.m. Pacific daylight time a magnitude 5.1
earthquake shook Mount St. Helen. The bulge on the North side of the mountain
gave way in a gigantic rock slide releasing pressure and triggering a major rock
and pumice eruption . At thirteen hundred feet the peak collapsed and as a result
24 square miles of the valley was filled with rock and debris. From that rock slide
250 square miles of timber, recreation and private lands were demolished from the
lateral blast. For more than nine hours the volcano spit vigorous ash in a large
plume. Eventually the plume reached 12-15 miles above se...

Mount St. Helen

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