John and Cathryn,
We really did not get beyond that he doubted that you could have large earthquakes on the same segment of the same fault without reloading the stress. Then, because it was getting too technical really quickly for me (esp. given the setting: in front of a beer on a Friday evening) I put the conversation off until later. I had not even heard the term "critical stress" for 15 years since I took seismotectonics. But, Cathryn, yes I have a bit of a problem with a fault storing enough stress for multiple earthquakes (without reloading the stress, which is normally but not always done by moving one side of the fault past the other (at a distance and at depth)). John and I had a debate on a thread below...although for a lot of that John was talking about one thing, and I was talking about another (rather specific) thing. I agree with John that if you have a large earthquake you are more likely to have other large earthquakes in the area (maybe 5 rupture lengths area...say, much of southern California for a M7..), and that even if blocks across a fault segment like Coachella of San Andreas have moved 10 meters without an earthquake, if you had a large earthquake on, say, the Cholame segment it would be more likely to have an earthquake within months or years on the adjoining Carrizo segment, or on a thrust off to the east, or whatever, than on the more distant Coachella. But, I am claiming that it is highly unlikely to have a repeat earthquake on the Cholame (say, not another M7 within days, months, or few years), and it would be more likely that the Coachella would fail first...because it can.

This discussion is a little dangerous for me since you both know who I am and I am rusty on stress etc (and may not have been exposed to some of this). But both of heartland wife's grad students are taking heartland Bob's advanced structure class, and I am joining the 2 students and wife in a weekly discussion seminar, and both students may be doing structure term paper on stress/New Madrid...so in the next month or 2 I may have read some papers on this: I found Weldon et al GSA Today paper on Wrightwood online and sent it to them, and we also may read Dolan et al Sept 2007 Geology paper (I think I read it already). We are going to read a Chris Scholz 1985(?) paper, and I suggested we read a much more recent Scholz paper on a strong San Andreas fault. I heard Scholz present this at Lamont-Doherty/Columbia NY and tend to prefer the weak fault idea that has been around for 20 years or so.
So, I can't answer John's questions without asking heartland Bob the questions...which maybe I will.
Stay tuned, but may be a while.
Hey Cathryn: I made it through the Palos Verdes manuscript draft although a couple of thesis figures need to be replaced and all figures and captions need some work.
Chris