SEATTLE — State officials have released new information about what a tsunami produced by a major earthquake on the Seattle Fault could do to Seattle and Puget Sound.
The study prepared by geologists from the Washington Geological Survey Division of the Department of Natural Resources was conducted to help local and state emergency services prepare for a tsunami in the Seattle area.
“The Seattle Fault traverses east to west through Puget Sound and downtown Seattle and has produced several documented earthquakes in the region’s geological records,” a press release for the report said.
The report reveals that tsunami waves would reach shore in less than 3 minutes at many locations along the east side of Bainbridge Island, Elliott Bay and Alki Point.
It also shows that flooding could exceed 20 feet along the shores of the greater Seattle area. According to the report, flooding and strong currents could continue for more than 3 hours from the start of the earthquake.
Experts agree that the likelihood of this happening is very low, but it is a sufficient possibility for the geologists of the Ministry of Natural Resources to have conducted their own study.
“The last known earthquake on the Seattle Fault occurred approximately 1,100 years ago. However, geological evidence shows that five additional earthquakes with an estimated magnitude of 6.5 have occurred in the area of the Seattle Fault over the past 3,500 years,” said a Department of Environmental Services press release. natural resources of Washington State.
The Seattle Fault traverses east to west through Puget Sound and downtown Seattle.
“Most often when we think of tsunamis, we think of our outer coast and the communities along the Pacific Ocean. But there is a long history of earthquakes on faults in Puget Sound,” Public Lands Commissioner Hilary Franz said. “While the history of earthquakes and tsunamis along the Seattle Fault is less frequent than in the Cascadia Subduction Zone, the impacts could be massive. That’s why it’s critical that these communities have the information they need to prepare and respond.
Although the study found that the 6 feet of flooding at Tacoma Harbor would be less than previous studies, it also found that waves can travel up to 3 miles inland in some parts of the port.
While tsunami flooding would be greatest near the Seattle Fault, the study showed shoreline flooding and increased currents throughout the Salish Sea from Blaine to Olympia.
The earthquake scenario used for the study was for a very large low-probability 7.5 magnitude earthquake, which produces the most highly regarded Seattle Fault-generated tsunami for emergency planning purposes.
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