Hi Todd. I think it may be that the fault systems in the Bay Area aren’t nearly as complicated as those in Southern California. I’m fairly sure we have some unknown faults in the Bay Area, but I would be willing to bet that Southern California has more then the Bay Area.

I think the quake history is a little better understood in the Bay Area, but the Rodgers Creek fault and the Monte Vista thrust fault are a couple of unknowns in the history department. It’s known that the Rodgers Creek fault has had a quake in the M=7.0+ range, but when that occurred isn’t that well known. The same thing applies to the Monte Vista thrust fault. I have never seen anything that has indicated when the last quake occurred on that fault. It is believed though that when it goes it can cause as much if not more damage then a quake of the same magnitude on the Hayward fault.

To a certain extent the Mount Diablo thrust fault is kind of like the area depicted in the link. It is in between the Hayward and Calaveras fault (may be the Hayward and the Concord/Green Valley fault) and is caught in a squeeze play with enough motion to cause Mount Diablo to be rising at the rate of 2mm per year.

I think the other reason we don’t see very much about what’s going on in Southern California is that no one wants to come out and say this is happening and because of that this is going to happen only to learn a year from now that what was said was completely wrong. Then again it could be that no one really knows and no one is willing to speculate. Take Care…Don in creepy town