Periodicity and Clustering in the Long-Term Earthquake Record

Elastic rebound theory forms the basis of the standard earthquake cycle model and predicts large earthquakes to recur regularly through cycles of strain accumulation and release. Yet few individual earthquake records are sufficiently long to test the theory. Here we characterize the distribution of earthquake interevent times from a global compilation of 80 long-term records. We find that large earthquakes recur more regularly than a random Poisson process on individual fault segments. The majority of Earth's well-studied faults shows weakly periodic and uncorrelated large earthquake recurrence, consistent with the expectations of elastic rebound theory. However, many low activity-rate (annual occurrence rates < 2 x 10(-4)) faults show random or clustered earthquake recurrence, which cannot be explained by elastic rebound theory.