Mount St. Helens National Volcanic Monument

Mount St. Helens on May 18, 1980On the morning of May 18, 1980, a magnitude 5.1 earthquake triggered the collapse of the summit and north flank of Mount St. Helens and formed the largest landslide in recorded history.

Gas rich magma and super-heated groundwater trapped inside the volcano were suddenly released in a powerful lateral blast. In less than three minutes, 230 square miles of forest lay flattened. The hot gas and magma melted the snow and ice that covered the volcano. The resulting floodwater mixed with the rock and debris to create concrete-like mudflows that scoured river valleys surrounding the mountain.

A MSH Coldwaterplume of volcanic ash and pumice billowed out of the volcano reaching a height of 15 miles and transformed day into night across Eastern Washington. Avalanches of super-heated gas and pumice, called pyroclastic flows, swept down the flanks of the volcano. While the landslide and lateral blast were over within minutes, the eruption column, mudflows and pyroclastic flows continued throughout the day and following night.

By the following morning major eruptive activity had ceased and the landscape appeared to be a gray wasteland. More than two years after Mount St. Helens erupted, Congress created the 110,000-acre National Volcanic Monument for research, recreation, and education. Ronald Reagan signed public law 97-243 on Aug. 26, 1982, formally designating the Mount St. Helens National Volcanic Monument. From this wasteland, new life soon emerged and thrived. The following decades have offered insight into the biological recovery of ravaged landscapes.

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Each year, over 10,000 students travel to Mount St. Helens to see the dramatic effects of the 1980 volcanic eruption, and observe how plants and animals have responded.

  • Mount St. Helens Photos

    Large pumping barge at Spirit Lake.

    View historic Mount St. Helens photos on Flickr.

  • Poster of a Mountain Reborn

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    View a high-resolution poster depicting Mount St. Helens, A Mountain Reborn, created by the Washington Department of Natural Resources.

  • Video Library

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    View a range of videos about the story of Mount St. Helens violent eruption to the legacy of transformation and biological research on the mountain.

Science & Research 

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