New Study Shows How Fast a Tsunami Could Flood an Inland City
Earthquakes and resulting tsunami events have long been a worry for the U.S. west coast – but while the main area of concern has been for coastal communities, a new study shows how quickly it could overwhelm a major inland city like Seattle.
The study, published by the Washington State Department of Natural Resources, examined a potential quake originating from the Seattle fault (probability of 5-7% likelihood in the next 50 years). On a magnitude 7 or greater earthquake along this fault, the city would be flooded by a 20-foot tsunami almost immediately, giving residents only three minutes to seek higher ground – significantly faster than researchers expected – as it continued to pour through the city for more than three hours.
While most northwestern area residents think more about the Cascadia Subduction Zone and its 15-25% of occurrence, the point of the study, according to lead author Alex Dolcimascolo, was to bring awareness to less-likely but still highly dangerous catastrophes.
“Most people in Puget Sound felt they were kind of safe, I think, feeling that the Pacific Coast was more the tsunami threat zone from Cascadia .… We wanted to look at this one end of the spectrum for emergency preparedness reasons so people can be aware of potentially that maximum scenario that could occur.”
As part of their preparedness efforts, the state hosts the Great Washington ShakeOut every October, and provides pedestrian evacuation walk maps to educate the public on routes to take in the event of a sudden catastrophic event.