[link to s1206.photobucket.com]

Here is dangerous places and earthquake pressure flow below USA, have three main dangerous "line"

One "line" you can see on images, other is San Andreas fault line, Third "line" is areas off West Coast of North America to Alaska ..

This main line collide or merge in areas of N Ca, WA, off Cost Oregon, British CO somewhere probably in ocean

Ocean crust is much shallower or thinner from continental crust so It's easier to break or crack also because tidal forces ..

In other picture you can see most dangerous area for biggest earthquake, that's how I see things ..