Carol...not exactly my speciality, but I can answer this with confidence...it added to the stress south of Parkfield..meaning, it probably increased the shear stress along the fault to the south, which means the fault is weakened. It probably had no effect on the San Andreas far to the south, where Don is talking about. Don...that 25 mm/yr on southern San Andreas may not be correct...some think that the southern San Jacinto fault is slipping that fast so there is less for San Andreas....but this is probably not proved yet. Because faults are locked, hard to tell which fault is contributing how much to the GPS motions.
Chris