Roger...I don't know what is going on but it seems worth pursuing. Hopefully John V. will visit these threads and add his opinions. It seems like what are are doing is simple and therefore not subject to which statistical test or whatever...although there are a couple of people who post here who might have comments. I suggest you go after some other regions that have complete catalogues to small magnitudes...like Long Valley. Maybe Brawley seismic zone and the other pull-aparts up to the north end Gulf of California (although you may run into incomplete for small magnitudes in Mexico...not as good a network? Someone can seach the archives and look for posts a couple years ago where suppression of quakes was discussed...some complicated hypothesis...I would guess from Lowell Whiteside.
Cathyryn...1/2 as many quakes is as interesting as twice as many, although a cause and effect instinctively seems less likely.
One other avenue: it is probably know what effect magnetic storms have on telluric(?) currents in the earth...what are these, how deep could they have an effect, what it might have to do with fluids. I don't know the answers to any of this.
Chris