Earthquake recurrence on whole active fault zones and its relation to that on individual fault-segments

Based on the earthquake data of 11 active intraplate fault zones of the Chinese mainland, we have studied the earthquake recurrence behaviors on entire active fault zones and their relations to those on individual fault-segments. The results show that the earthquake recurrence on entire active fault zones, each of them is made up of multiple segments, displays three types of behavior, i.e., the clustering behavior, the random behavior, and the poor quasi-periodic behavior. The major one is the sparse clustering behavior, its recurrence process often exhibits that clusters (active periods) and gaps (quiescent periods) occur alternatively in varying degrees. The recurrence intervals within and between clusters, the durations of individual clusters, the earthquake number and strength of every cluster are all variable. The recurrence process is non-linear, there is neither the strength-time dependence nor the time-strength dependence. However, the earthquake recurrence processes on individual fault-segments are much more simple, and mainly display either the quasi-periodic or the time-predictable behaviors. Also, this study further discovers that the temporal clustering in earthquake recurrence process on entire fault zones is mainly caused by the rupture (contagion( on different fault-segments within relatively short periods of time. Along active fault zones, the degree and orientation of rupture (contagion( may vary with different seismic cycles, and the (contagion( seems to be able to jump over unbroken (gaps( on the fault zones.