Hmmm...I partly don't agree with Marc's science on the offshore earthquakes. Earthquakes are located by waves that propagate through the rock, not the water (although sound in water is used for, for example, locating smaller distant volcanic quakes on ocean spreading centers). Because there are much fewer seismic stations offshore (mainly on islands), offshore quakes are harder, not easier, to locate. You also don't have nearly as much GPS control to detect strain. The weight of the water has little to do with anything unless you suddenly removed everything (you pulled the plug in the middle of the ocean and it all drained out?)...I suspect that earth tides and ocean tides have similar effects or lack thereof. And, I don't find the offshore quakes the last year to be unusual...activity in Santa Barbara Channel is probably still depressed relative to before the 1980s...and even some of the larger ones elsewhere are not all that unusual. You could always take Roger's program and run M3+ quakes through it since, say, 1970 and see if there is really increased activity offshore....I think the answer would be "no"...after taking into account that we can probably detect them better since the 1980s than in the 1970s..
Chris