History & Culture

Mount St. Helens District Ranger Ken Johnson, Spring 1980
At 8:32 Sunday morning, May 18, 1980, Mount St. Helens erupted.

Shaken by an earthquake measuring 5.1 on the Richter scale, the north face of this tall symmetrical mountain collapsed in a massive rock debris avalanche. In a few moments this slab of rock and ice slammed into Spirit Lake, crossed a ridge 1,300 feet high, and roared 14 miles down the Toutle River.

Mount St. Helens and Spirit Lake, 1992The avalanche rapidly released pressurized gases within the volcano. A tremendous lateral explosion ripped through the avalanche and developed into a turbulent, stone-filled wind that swept over ridges and toppled trees. Nearly 150 square miles of forest was blown over or left dead and standing.

At the same time a mushroom-shaped column of ash rose thousands of feet skyward and drifted downwind, turning day into night as dark, gray ash fell over eastern Washington and beyond. Wet, cement-like slurries of rock and mud scoured all sides of the volcano. Searing flows of pumice poured from the crater. The eruption lasted 9 hours, but Mount St. Helens and the surrounding landscape were dramatically changed within moments. A vast, gray landscape lay where once the forested slopes of Mount St. Helens grew.

A National Monument

In 1982 the President and Congress created the 110,000-acre National Volcanic Monument for research, recreation, and education. Inside the Monument, the environment is left to respond naturally to the disturbance.


Gifford Pinchot National Forest History

Photo of Mount St. Helens before the 1980 eruption.

Mount St Helens National Volcanic Monument is within the Gifford Pinchot National Forest and more than 6,000 years, people have played a part in the ecology of the area. The earliest Native Americans hunted in meadows below receding alpine glaciers. Archaeological investigations on the Forest continue to discover new and exciting information about the lives of the first Americans.