Probability of one or more M ≥7 earthquakes in southern California in 30 years

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).