We've been having some minor tremblies up here this past month- the last ones were in 2001, when we had a series of 2.5 to 4.5's over a period of six months. Not a big deal to you seasoned Californians, but we didn't know we were earthquake prone and now the scientists have discovered some very old fault lines, one of which literally runs under our house.
They tend to be very shallow, which the seismologists find concerning. (I don't know why, but that's what it said in the paper).
Keep safe and make sure you have your emergency kits ready- a 5.6 is a bit large to ignore!