Record-Breaking Earthquakes

A record-breaking earthquake has a larger magnitude than any previous earthquake in the study region. A starting date and minimum magnitude must be specified. The first earthquake to satisfy this condition is by definition a record- breaking earthquake. The next record-breaking earthquake has a larger magnitude than the first and so forth. In this paper we utilize the global CMT catalog for the years 1977 to 2006. We consider both the entire period and the set of two- year sub intervals. We determine the number of record-breaking earthquakes during the specified intervals, their magnitudes, and their times of occurrence. We compare the results with the predictions for a random (iid) process. One prediction is that the magnitude differences between successive record-breaking earthquakes is a constant. A second prediction is that the difference between the logarithms of the times of occurrence of successive record-breaking earthquakes is a constant. Good statistical agreement between the observations and the predictions is obtained. It is interesting to note that an aftershock cannot be a record breaking earthquake by definition.