Preliminary Study on Shallow Seismic Activity Model in Taiwan Region
This paper compiles an earthquake catalogue dataset containing earthquakes with magnitudes above ML2.0 and focal depths less than 350 km,sourced from the Taiwan Meteorological Bureau(CWB)for the period from 1900 to 2022.All magnitudes in this catalogue are standardized to moment magnitudes(MW).Utilizing this dataset,we analyze the characteristics of seismic activity in Taiwan and discuss the historical evolution of the lower limit for completeness magnitude(Mc)recorded during different periods.To re-fine the earthquake catalogue,we apply the widely used Gardner-Knopoff declustering method to remove foreshocks and aftershocks.Three time-distance window parameters-Gardner-Knopoff,Grünthal,and Uhrhammer-are employed to derive the corresponding mainshock catalogue through calculations.Our findings indicate that different declustering methods significantly impact the resulting earthquake catalogue.In this study,we recommend the Gardner-Knopoff declustering method combined with the Uhrhammer time-dis-tance window parameters for effectively removing foreshock and aftershock events.We emphasize that epistemic uncertainty arising from various declustering approaches must be considered in probabilistic seismic hazard analyses.The completeness of the earthquake catalog in Taiwan is assessed using the Stepp(1971)method,which establishes completeness times for each magnitude bin based on the point at which the estimated variance of the average earthquake occurrence rate deviates from the expected regression line,thus minim-izing subjective bias.Finally,we estimate the activity parameters of the Gutenberg-Richter(G-R)relationship in Taiwan using maxim-um likelihood estimation methods developed by Weichert(1980),Bender(1983),and Kijko et al.,(2012).The results of this research provide valuable data inputs for future probabilistic seismic hazard analyses in Taiwan and serve as a reference for calculating seismic activity parameters for the upcoming seismic ground motion parameters zonation map of China.
Earthquake catalogueSeismicityDeclustering methodCompleteness of earthquake catalogueMaximum likeli-hood estimation
万方数据
维普
