Oh dear Lord, there'd be a fair amount of that whole I-5 corridor along your route that'd be toast. So much of it is elevated, but I gotta think in a quake you'd have Queen Anne and Capital hill structures come tumbling down onto the freeway anyways. I always figured if the big one hit when I was living there, it'd be about as bad as it could get just about anywhere on the planet. Then there's the big tidal surge rebounding around in Elliot Bay and Hood Canal and such. It would not be fun to be skirting through Fife on I-5 or old 99 and watch the big wall of water either coming up the tidal flats Tsunami style, or down the Puyallup River valley as a La Har from Bonney Lake, Twin Lakes, and Mud Mountain Dam all letting go. Ugly!

I always figured the best bet would be to head east and get to high ground skirting the cascades from Issaquah through Black Diamond and around to Enumclaw. It is the long way around, but at least you'd be away from the urban hazards and most of the reservoir water. That's assuming Mount Rainier doesn't let go and blast the whole area to heck.

I see U of W is still predicting a force 9+ quake as imminent along the Juan de Fuca line. That'd pretty much make most of the urban sprawl along the I-5 corridor and along the west side (Bremerton) disappear I reckon.