Tsunami waves as high as 42 feet could crash into Seattle within minutes of an earthquake on Seattle Fault, study finds

A single earthquake in Seattle could cause a catastrophic situation for the northwest corner of the state, a new report from Washington's Department of Natural Resources found. 

The study was focused on the Seattle Fault, located beneath the Puget Sound and the city of Seattle. Researchers developed modeling scenarios based on the impacts of the last tsunami-triggering earthquake in the region, which occurred about 1,100 years ago. That earthquake on the fault is believed to have been between a 7.0 and 7.5 magnitude event and researchers said in their report that it may have been the only large earthquake on the fault within the past 16,000 years. 

However, they said, "the fault is still active and is capable of generating similar tsunamigenic earthquakes today." 

Hilary Franz, commissioner of public lands, said, "the impacts could be massive." 

"Most often, when we think of tsunamis, we think of our outer coast and communities along the Pacific Ocean," she said. "But there's a long history of earthquakes on faults in the Puget Sound."

If a roughly 7.5 magnitude quake were to happen on the fault line today, simulations show that tsunami waves would travel through the Puget Sound, Rosario Strait and the Strait of Georgia. It would impact the shoreline from the Canadian border to Olympia within 1 to 2 hours. 

Within just 3 minutes, the first tsunami wave would hit the greater Seattle area, according to the simulations. Waves could last more than 3 hours and the department said that they could be as high as 42 feet at the iconic Seattle Great Wheel. Waves could overtake Lumen Field, the home of the Seattle Seahawks, and in some areas of impact, waves could travel up to three miles inland. 

The department conducted the study as part of the state's efforts to create tsunami response and preparedness plans. More than 760,000 people live in Seattle, Washington's most populated city. 

Researchers said the most recent earthquake that hit the area was so massive that it pushed a beach on Bainbridge Island upward by 23 feet while also dropping land at Seattle's West Point by 3 feet. The next earthquake could create a new shoreline, they added. 

"Although the chances of this happening in our lifetime is low, it's important for families to get prepared now," Maximilian Dixon, hazards and outreach program supervisor for the Washington Emergency Management Division, said in a statement. "The ground shaking will be your warning that a tsunami may be on the way. Make sure you know where the closest high ground is and the quickest route to get there. Get signed up for tsunami and local alerts."

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