The slip rate budget of the San Andreas fault (SAF) in central California, which is approximately 33 mm/yr, is accounted for by a change in the slip release mechanism along the fault. In the NW section of the fault, between Bear Valley and Monarch Peak, creep apparently accounts for the slip budget with the seismicity contributing negligibly. The section at Parkfield marks the transition from a creeping to a locked fault trace. Since the M8 1857 earthquake five M6 earthquakes have occurred but have not completely accounted for the slip budget. Southeast of Parkfield, the SAF has been locked since 1857. From Cholame to Bitterwater Valley this section now lags the deep slip by the amount of slip released in 1857; consequently faulting in this section could occur at the time of the next Parkfield earthquake. If this earthquake releases the slip deficit accumulated in the transition zone and in the locked zone, the earthquake will have a moment-magnitude M7.2. ¿ American Geophysical Union 1988