There was a M5.7 offshore San Diego, near the offshore Mexican Border. Looks on the small NEIC/SCEC map that it is on or west of the San Clemente fault, which is a big active right-lateral fault. There may have been a small quake before it on a closer offshore fault....

Half way between the quake and San Diego (if the quake is accurately located), is an enormous potential landslide block on 30 Mile Bank, into San Diego trough. But, it been sitting there a long time......

more later.

Chris