No idea how I came to looking at this today, but there's an interesting "scenario" report for a M9 earthquake on the Cascadia subduction zone available at [www.crew.org]. Might be interesting to look at and think about.

It goes into fair detail about how such a quake would happen and what the effects might be. There's some info about highways and pipelines under transportation effects, but rail gets kind of a light touch. Given the intensity projected, several lines would likely be out of business for a while, even if only a few spots (Newport, Coos Bay, Tillamook, Astoria, Aberdeen, Eureka areas) might be exposed to any real tsunami damage (waves would likely not be much by the time they reached inland to Portland and Seattle. I expect the railroads were consulted or are aware of the scenario and use it for planning.

Just FYI, the CA North Coast has more frequent "moderate to large" earthquakes (6-7 or so, causing damage) than the rest of the state. Only one of the recent ones (in the early 1990s) might have been on the subduction zone (south end, on land, but did cause a small tsunami due to uplift of the coastline around Cape Mendocino). But a moderate to large quake near you can make a bad day even if it doesn't affect a large area (e.g. Northridge, which actually wasn't a really big quake but the type of faulting and location made it bad).