Here's a NY Times opinion piece by a structural engineer:
Shake, Rattle, Seattle; By PETER YANEVMARCH 27, 2010
These are the words of someone reasonable about the topic, instead of selling sensationalism.
I don't know how accurate this is. Afterall, the Cascadia fault is out in the Pacific, far away from Seattle and Portland, whereas the Andeas fault is close to LA, and runs right under SF. I don't know how that calculates out, but a 9.5 quake at the fault would I would guess would be under a 5.0 that far away. I felt a 5.6 back in 1993 when I lived in Aloha and was close to the origination. It was definitely a shaker, but nothing happened other than things shaking off tables and walls. I'll bet it lost two or more magnitudes by the time it got to where I lived.
Now a sizable tsunami would roll water down the Columbia river, and likely flood Portland, but there would be at least a hour or more warning to get off the riverfront areas. I don't know Seattle well enough, and the bay would definitely allow more water than the Columbia river.
