First, it wasn't clear from your post, but you probably know this: the subduction zone earthquakes we examined are also thrust faults, just like the thrust faults on land that you mention. The tides, as you surmise, get smaller as one goes inland from the coast to reach the San Andreas in our neighborhoods. The biggest factor, however, is the California tides are not very large, so both the strike slip faults and the thrust faults are not much effected by the tidal stresses.

Which paper are you reading? We had one in JGR in 1998, where California faults showed a couple of percent or less change in rates with the ebb and flow of the tides. We just had another in SRL showing that the biweekly tides don't affect earthquake rate significantly on the west coast (to Jim Berkland's dismay). There will be a third in Science in a couple of weeks that appeared first in Science Express last week showing in a few places, the tides strongly affect the rate of earthquakes.

Your sense of the loading is better than most of the reporters - low tides encourage low-angle thrust earthquakes under the coast.

John