Glen, there is a third group, those young faults where we don't know recurrence interval. This includes all the faults that remain offshore, and most of the blind thrust faults. But, you can probably assume that the offshore faults have slip rates in the 0 to 3 mm/range and so for any one section of any one fault, it would take a relatively long time to accumulate, say, 2 m of slip (1000 years for 2 mm/yr). On the other hand, the work since 1992 in the Mojave has shown that earthquakes on at least those faults plus the San Andreas at Wrightwood are clustered.
Chris