glen;

here are the mag 6+ quakes from 1980-2009

1980,06,09,032818.90, 32.22,-114.99,6.1, 5
1981,04,26,120928.40, 33.13,-115.65,6.3, 6
1986,07,08,092044.50, 34.00,-116.61,6.1, 12
1987,11,24,015414.51, 33.08,-115.78,6.5, 4
1987,11,24,131556.40, 33.01,-115.84,6.7, 2
1992,04,23,045023.22, 33.96,-116.32,6.1, 12
1992,06,28,115734.12, 34.20,-116.44,7.3, 1
1992,06,28,150530.70, 34.20,-116.83,6.5, 5
1994,01,17,123055.39, 34.21,-118.54,6.7, 18
1999,10,16,094644.13, 34.59,-116.27,7.2, 0

That's 10 in 30 years, one every 3 years on average.
But since some years had more than one it's really
more like one every 5 years.

But the last one was 12 years ago you might say we're
overdue. What's more likely is that the energy is
concentrated somewhere else.

Roger