Recurrence Statistics of Great Earthquakes
E. Ben-Naim, E.G. Daub, P.A. Johnson
We investigate the sequence of great earthquakes over the past century. To
examine whether the earthquake record includes temporal clustering, we identify
aftershocks and remove those from the record. We focus on the recurrence time,
defined as the time between two consecutive earthquakes. We study the variance
in the recurrence time and the maximal recurrence time. Using these quantities,
we compare the earthquake record with sequences of random events, generated by
numerical simulations, while systematically varying the minimal earthquake
magnitude Mmin. Our analysis shows that the earthquake record is consistent
with a random process for magnitude thresholds 7.0<=Mmin<=8.3, where the number
of events is larger. Interestingly, the earthquake record deviates from a
random process at magnitude threshold 8.4<=Mmin<= 8.5, where the number of
events is smaller; however, this deviation is not strong enough to conclude
that great earthquakes are clustered. Overall, the findings are robust both
qualitatively and quantitatively as statistics of extreme values and moment
analysis yield remarkably similar results.
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