[hoagy62]

Here is a video put out by WSDOT of what might happen in the event of an earthquake to the Alaskan Way Viaduct and the Seattle waterfront. It was done a few years ago. In it, the earthquake was supposed to be around the same magnitude as the 2001 Nisqually Quake, but closer to Seattle. If the Cascadia lets go with the full-margin rupture (also called the 'Full 9 Rip'), the results would likely be much, much worse.

Computer Simulation of Seattle Waterfront in an Earthquake

[CommerceComet]

That video is interesting. I was a Ph.D. student in Seattle when the SF World Series earthquake hit. The highway that collapsed there was of the same design as the Alaskan Way Viaduct. Always made me nervous when I drove over the viaduct. Wouldn’t want to be under it or on either level when the big one hit.

Apparently, the tsunami danger depends on the epicenter of the quake. The simulated quake in the video didn’t trigger one but I have seen some projections about tsunamis when the epicenter is just off the coast near the mouth of the Strait of Juan de Fuca. With little warning, tsunamis could race up the Strait and down the Puget Sound causing horrific damage to the cities along the shores including Vancouver, BC, and Seattle/Tacoma area. Apparently, the geologic record in the area shows a history of massive tsunamis.