5.8 earthquake in Washington

There's also the fact that earthquakes on each coast are different due to the landtypes, earthquakes travel further here.

Also, last time I checked, we don't have major faults on this coast. How did this even happen?

I know it's wikipedia, but you can research it more if you want:

http://en.wikipedia.org/wiki/Intraplate_earthquake

It's basically a fault within a plate, so in a way it acts like a normal fault, just on the plate itself and not the actual fault line between 2 plates. it's like having a tiny scratch on a smooth surface.