Hi Todd, yes, interesting. But, have you read anything on the earthquake history from trenching? And, does GPS modeled for locked faults give a rate of strain accumulation? If sub-parallel faults are too close together to locked faults it is hard to tell which fault is going to release how much of the motion. Perhaps the most reliable way to get a slip rate is to just use the creep rate on the Calaveras fault in a place Hollister where it is all creep. I recall that it is pretty fast...10 mm/yr?? less? I went there 22 years ago on a field trip and saw the offset sidewalks and house(s).

Also, I'm not looking at the fault map, but assume this fault runs far to the North and northwest, so probably could be occasionaly capable of a larger quake.

We've been looking at our very high resolution acoustic data (chirp seismic reflection) of the mostly left-lateral fault that broke in the 2010 Haiti quake. It looks like at least a 2 km-wide zone in Grand Goave near the coast (but offshore). The fault zone may be trying to step left. oblique thrust faults intersect it in this area, and were probably involved in th thrust aftershocks. Maybe your saying the Calaveras loses its trace is realted to a stepover or bend to the Concord or intersection with another fault?

I know very little about the Concord, and the east bay faults in general.
Chris