Aftershock probabilistic seismic hazard analysis based on ETAS model
Aftershock probabilistic seismic hazard analysis is of vital importance in seismic risk assessment after the mainshock.The conventional framework for such analysis relies on the Reasenberg-Jones(R-J)model.However,it is known that the R-J model may exhibit shortcomings in predicting complex seismic sequences.Therefore,this study integrates the epidemic-type aftershock sequence(ETAS)model,which provides a more comprehensive representation of real-world aftershock sequences into the framework of aftershock probabilistic seismic hazard analysis.To demonstrate this integration,two real-world scenarios were examined including the aftershock sequence following the 7.9 magnitude Wenchuan earthquake in 2008 and the aftershock sequence after the 6.2 magnitude Ludian earthquake in 2014.The purpose is to highlight the significance of evaluating aftershock hazard levels and to investigate the differences between the ETAS model and the R-J model in the context of probabilistic seismic hazard analysis for aftershocks.The results underscore the correlation between the hazard levels of aftershocks and the magnitude of the mainshock.Notably,larger mainshock magnitudes are associated with elevated aftershock hazard levels and prolonged durations.For substantial mainshock events with higher magnitudes,the hazard posed by early-stage aftershocks following the mainshock cannot be disregarded.Furthermore,the result reveals that the ETAS model outperforms the R-J model in terms of predicting aftershock incidence for the Wenchuan earthquake and the Ludian earthquake.In the assessment of aftershock hazard,the magnitude of such hazard is contingent upon the rate of aftershock incidence.It is noteworthy that the aftershock incidence by using the R-J model exceeds that derived from the ETAS model.Consequently,employing the R-J model in aftershock hazard assessment leads to an overestimation of the level of aftershock risk compared to that of the ETAS model.The ETAS model can be utilized to enhance the aftershock probabilistic seismic hazard assessment framework.
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