As you probably know Parkfield is known as the earthquake capital of the world. It's near Coalinga and on the San Andreas Fault. They have a seismograph there, several actually, that you can watch recording... there's a small quake happening nearly at all times. Guaranteed if you stop to look you'll see a quake recorded, but almost always so small you can't feel it.

Also, along the San Andreas there are many places that actually did 'open up'. But you're right, that's not likely.