Puget Sound Earthquake – Washington – April 13, 1949

An eighty-mile coastal strip from Seattle to Chehalis was severely damaged.

On April 13, 1949, a 7.1 magnitude earthquake occurred in western Washington. Its epicenter was close to the coast between Olympia and Tacoma and it was felt strongly in Washington, Oregon, Idaho, and British Columbia. It was the largest earthquake in Puget Sound since 1700. Eight people were killed and dozens received serious injuries.

Greatest damage was experienced along an eighty-mile coastal area from Seattle to Chehalis. Approximately 40 percent of Chehalis’ business buildings and houses were damaged and more than 10,000 chimneys in Washington required repair. The value of the damage caused was $25 million.

Eight buildings at the state capital in Olympia were damaged. A large sandy spit jutting into Puget Sound north of Olympia disappeared. In Portland, the earthquake caused rockslides and cracks to buildings. Earthquake damage in Seattle included the quake’s strongest ground shaking. Damage was considerable to well-built structures and extensive to poorly built ones. Some buildings collapsed. Chimneys, factory stacks, columns, and monuments fell. Heavy furniture overturned and people had difficulty driving.

Three schools received major damage and were ultimately condemned. At Lafayette Elementary School in West Seattle, the large brick gable over the main entrance collapsed. Three bridges crossing the Duwamish River were jammed shut due to shifting earth. Cracks opened in the earth near Green Lake. Numerous brick walls throughout the city collapsed, fractured, or bulged. They were all condemned.

Many houses in Seattle that were built on filled areas were demolished and, in some places, the ground turned to quicksand causing floors to crack and basements to fill with silt. Cracks opened in the ground, some spouting water six feet high. Seattle gas lines broke in one hundred places but fortunately no fires occurred. This has been a common problem in coastal cities on U.S. coasts. The experience of San Francisco both in 1906 and in subsequent earthquakes is a classic illustration of the problem.

Cities extend their footprint by reclaiming land from the sea. Rarely are the new foundations designed for the support of new buildings. Thus, when an earthquake strikes, liquefaction takes place as a result of the shaking and the former surface beneath buildings becomes a muddy mass unable to sustain any weight. Farther south of Seattle, near Tacoma, a two hundred-foot-high cliff collapsed into Puget Sound. In the same area several railway bridges were thrown out of alignment.

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