Petra...I'll let John answer most of those questions...but, I'll add a related comment. Most of the aftershocks of Parkfield are along the part of the San Andreas fault that broke during the earthquake....it did not just break at the epicenter (in 3D, you refer to a hypocenter). It is just that the rupture started at the hypocenter (epicenter is point on ground above hypocenter), and within a few seconds had ruptured mainly north.

I was noticing a little cluster of small quakes a couple of weeks ago near the surface location of the San Simeon fault...the right-lateral strike-slip fault...near the coast but offshore to the northwest of San Simeon...offshore quakes, including near the San Simeon fault, occurred soon after the San Simeon quake (which was on an inland thrust fault). So, an old idea from Lowell W. is that places that are lighting up like this are places to look later for large quakes....I don't know how well this works. But, I wonder if looking at spots like this for accelerating moment release (rather than a larger region) could tell you something...Chris