Mount St. Helens Eruption—Impact and Civil Engineering Response

Serial Information: Civil Engineering—ASCE, 1980, Vol. 50, Issue 8, Pg. 72-75

Document Type: Feature article


The May 18 eruption of Mount St. Helens in Washington state, estimated to have the energy equivalent of a 20 to 50 megaton atom bomb, did tremendous damage. It destroyed an estimated 160 sq mi of forest, flooded the Toutle and Cowlitz River valleys, and virtually closed the major shipping channel on the Columbia River between Portland, Oregon, and the Pacific Ocean. It covered the city of Yakima, Washington, 80 miles away, with a 1-in. blanket of ash. Yakima, biggest city heavily hit by the ash, lost its sewage plant for three days, had storm drainage systems plugged or impeded, had to close the downtown area to traffic for three days to permit cleanup. Hundreds of miles of highways were impacted—a car running over the ash kicked up a cloud that made visibility zero for some distance beyond, and wetted ash is as slippery as ice. The article, in pictures and words, describes the devastation created and details cleanup problems and solutions.

Subject Headings: Ashes | Urban areas | Drainage systems | Explosions | Forests | Floods | Freight transportation | Ocean engineering | United States | Washington | Oregon | Pacific Ocean

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