Washington state officials urged Seattle residents to prepare for a tsunami, even though the last known earthquake on the Seattle Fault occurred about 1,100 years ago.
SEATTLE — Tsunami waves from a 7.5-magnitude earthquake on the Seattle Fault would take just minutes to reach the Seattle area, according to a newly released study.
The Washington State Department of Natural Resources (DNR) released the new study Thursday, urging Seattle residents to prepare even though the last known earthquake on the Seattle Fault occurred about 1,100 years ago.
“While there is little likelihood of this happening in our lifetime, it is important that families prepare now,” said Maximilian Dixon, director of the Washington Emergency Management Division’s hazards and outreach program. “The ground tremor will be your warning that a tsunami may be on the way. Make sure you know where the nearest hill is and the quickest way to get there.”
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Tsunami waves would reach the shoreline in many places on the east side of Bainbridge Island, around Elliott Bay and Alki Point, in less than three minutes, according to the study, prepared by geologists with the DNR’s Washington Geological Survey division.
The study also found that flooding from such a tsunami would exceed 20 feet along the Seattle shoreline. The DNR said the study found that waves at the Port of Tacoma can travel up to 3 miles inland, although flooding would be less than previous studies.
Flooding from the tsunami will be greater near the Seattle Fault, but the new study showed coastal flooding and increased currents across the Salish Sea, from Blaine to Olympia.
The earthquake scenario used in the modeling is a “very large, low probability” magnitude 7.5 earthquake on the Seattle Fault, which runs east-west through Puget Sound and downtown Seattle. The fault has produced several documented earthquakes, according to the DNR.
The DNR said the model does not account for tidal stages or local tsunamis triggered by earthquake-related landslides.
“Most of the time when we think of tsunamis, we think of our outer shores and communities along the Pacific Ocean. But there is a long history of fault earthquakes in Puget Sound,” said Commissioner of Public Lands Hilary Franz. “While the history of earthquakes and tsunamis is less frequent along the Seattle Fault than in the Cascadia subduction zone, the impacts could be massive. Because of this, it is important that these communities have the information they need to prepare and respond.”
The study was conducted to help local and state officials develop tsunami response and preparedness plans.
The DNR offers many resources for families to be prepared in the event of an earthquake. If an earthquake occurs, the safest thing to do is to drop, cover and hold on, and then evacuate to higher ground to get as far inland as possible.
“We will continue to ensure our Office of Emergency Management — and all of our departments — are best equipped to respond to emergencies and natural disasters, while strengthening our infrastructure and building a resilient city now and for the future.” said Seattle Mayor Bruce Harrell.
The recent earthquake was strong enough to move the beach up 23 feet at Restoration Point on Bainbridge Island and sink land at Seattle’s West Point by 3 feet.
DNR said the next earthquake could create new shorelines in many places near the fault line.
Visit dnr.wa.gov/tsunami for more information and resources.
https://www.king5.com/article/tech/science/environment/tsunami-waves-seattle-minutes-earthquake-study/281-a7a69494-0f4e-4268-a395-e3d6585f0f89 Tsunami would reach Seattle in minutes after earthquake: Study