Mount Saint Helens
a volcano in the Cascade Mountains

May 18, 1980

Eruption Mount Saint Helens is a volcano in the Cascade Mountains, 95 miles south of Seattle. The volcano erupted violently on May 18, 1980 and resulted in 57 deaths. It also caused hundreds of millions of dollars of damage to the surrounding area. Volcanic explosions blasted away more than 1,000 feet from the peak and created a huge crater. The volcano's elevation after the 1980 eruption was 8,364 feet above sea level. The eruption was the first to occur in the continental United States outside Alaska since 1917, when Lassen Peak in northern California last erupted.

Two months before the eruptions a series of earthquakes signaled the awakening of the sleeping giant. Much of its north flank crumbled in a landslide that was the largest on Earth in recorded in history. The landslide depressurized the volcano, triggering massive explosions.

The blast devastated more than 230 square miles, blowing trees down like toothpicks. A column of ash shot 15 miles into the air, completely darkening Spokane, Washington, 250 miles to the east.

Photo, Peter Frenzen, 1980

Mount St. Helens has erupted many times in the past 4,500 years, but it was inactive from 1857 until 1980. River Before Eruption Hot ash and rocks from the 1980 eruption started forest fires and melted snow on the upper slopes of the mountain. The resulting floods and mud slides washed away buildings, roads, and bridges. Explosions flattened millions of trees. The eruption also spread a thick layer of volcanic ash over a wide area, destroying crops and wildlife and blanketing cities. Between May 1980 and 1986, many small eruptions occurred. But these did not result in deaths or significant property damage. Geologists expect Mount St. Helens to continue to erupt from time to time.

River After Eruption The river scene in the above USDA Forest Service photo, taken in 1978, while the same scene is shown in the 1980 photo, right, two years after the eruption. Blown down trees still point away from the blast where they fell.


Lake After Eruption The scene on the left shows the enormous devastation caused by the explosions. St. Helens is in the background. Note the barren hills on the extreme left of the photo.

The mountain's snowcapped cone, which peaked at 9,677 feet before the eruption, was gone. In its place was a gaping crater. The top 1,300 feet lay on the valley floor, as barren as a moonscape.
Photo, J. Frankling, USDA Forest Service, 1980

1996 View from Visitor's Center A 1996 view from the Visitor's Center provides a good look at the 300 foot crater left in the mountain top. The view cannot show the 1,300 feet of mountain top removed by the explosions.

Mount St. Helens is the most active of the Cascade Range, which stretches from Northern California to British Columbia. Its volcanoes have produced more than 100 eruptions in the past few thousand years.

Photo, J. Quiring, USDA Forest Service, 1996

1996 View from Visitor's Lookout Point A closer view of the cratered summit from the Visitor's Center Lookout Point.

Snow covers the lava dome bulging out of the crater. A slight shift of the mountain could send the snowpack sliding down, flooding valleys downstream.
Photo, J. Quiring, USDA Forest Service, 1996

Portions of text excerpted from May 16, 2000 article by Hunter T. George, Associated Press

Contributor: USDA Forest Service Web Site -

SOURCE of photos: USDA Forest Service

Contributor: Jois C. Child, Ph.D., Former Assistant Prof. of Geography, Eastern Washington Univ.

Additional resources

Carson, Rob. Mount St. Helens: The Eruption and Recovery of a Volcano. Sasquatch Bks., 1990.

Lauber, Patricia. Volcano: The Eruption and Healing of Mount St. Helens. Bradbury, 1986. Younger readers.

SOURCE of some text: IBM 1999 WORLD BOOK

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