Systematic fluctuations in the global seismic moment release

We revisit the significance of the increased number of great earthquakes since December 2004. An analysis of the global seismic moment release during 1918–2014 inferred from the International Seismological Centre catalog rejects a null hypothesis of independence between earthquake seismic moments and occurrence times. Our results suggest the existence of temporal variation in the seismic moment distribution on a global scale with decreased moment release during 1975–2004 and a transition to a regime with increased moment release during the 1960s and after December 2004. We use complementary likelihood and regression analyses based on nonparametric resampling and parametric Monte Carlo simulations to construct tests powerful enough to reject the null hypothesis of independence.