There is no such thing as a stupid question, so don't fear. Your questions are interesting ones. As usual in earthquake matters, it is difficult to give one simple answer. The Juan DeFuca plate and Gorda plate are still subducting beneath Northern Calif, Oregon and Washington. That will cause quakes and volcanic action for millions of years to come.

It is unlikely that a huge quake in these zones would cause much shaking/damage in the center of the states. The Coast would shake, and the tsunami threat will loom large. The eastern edges of the states will know about the quakes only when they turn on the radio and TV unless the epicenters were really, really close to the shoreline.

The subduction affects the continent several hundreds of miles inland with volcanic and other geologic hazards, however. A stress transfer will no doubt create a further potential for quakes, etc.

That's a pretty simple answer, but a very good question! Never stop asking questions, and always be skeptical about answers!

Cheers, PennyB