Eight earthquakes of magnitude greater than or equal to seven have occurred in southern California in the past 200 years. If one assumes that such events are the product of a Poisson process, the probability of one or more earthquakes of magnitude seven or larger in southern California within any 30 year interval is 67%¿23% (95% confidence interval). Because five of the eight M≥7 earthquakes in southern California in the last 200 years occurred off of the San Andreas fault system, the probability of one or more M≥7 earthquakes in southern California but not on the San Andreas fault system occurring within 30 years is 52%¿27% (95% confidence interval).