How often will earthquakes recur on the San Andreas Fault?

The relationship between magnitude and abundance of earthquakes, called a recurrence curve, has been derived for many regions of the world from seismographic records. AS an example, Clarence Allen and his associates at the California Institute of Technology have obtained recurrence rates for the southern California region by incorporating data from over 10,000 earthquakes recorded between 1934 and 1963. 

My own approach to estimating average recurrence intervals has been somewhat different. I have used the history of slip rates along the San Andreas fault that are preserved in the geologic record. The main advantage in this method is that is samples a very long period of time, which gives a better estimate of the recurrence of small earthquakes.