THE APPLICATION AND LIMITATION OF MULTIPLE SEISMICITY PARAMETERS TO ASSESSING CURRENT FAULTING BEHAVIOR AND SEISMIC POTENTIAL OF ACTIVE FAULT ZONES

In order to analyze the feasibility using seismicity parameters to identify current faulting behavior and hence to assess long-term seismic potential of active fault zones,we introduced the technique of spatially scanning and mapping b values along fault zones,as well as the procedure of data processing,calculating and result analyzing of multiple-seismicity-parameter-value combinations(i.e.b—,E,n and a—/b—)for various fault-segments in this paper.We then brought forward several reference criterions for fault segmentation,that is,the calculation of multiple seismicity parameters.Moreover,we generalized the approach and thinking of synthetically identifying spatial differences of current faulting behavior from the calculated parameters by combining histories of strong and major earthquakes and spatial distributions of modern seismicity.As an application,we took 5 active fault zones with various current seismicity levels and seismic detectabilities as the experimental targets to analyze synthetically the spatial differences of current faulting behaviors and identify fault segments with potential risk of strong earthquakes for each of the 5 fault zones basing on the generalized approach or methods.Meanwhile,the issues,such as the relation between the postseismic fault healing and relatively low b-value,the proper use of high-accurate re-located seismic data in the parameter calculating,and etc.have also been discussed.The results mainly suggest that the spatial distribution of multiple seismicity parameter values,among which the b-value is the most important one,can be effectively applied to analyzing current faulting behaviors and hence to identifying fault segments with potential risk of strong or major earthquakes.The two methods,the scanning and mapping of b-values along fault zones and the analysis of multi-parameter-value combinations for various fault-segments,can be applied to active fault zones in areas of high or moderate seismic detectability,respectively.And if the two methods are employed to areas with higher seismic detectability,more reliable results will be obtained.Fault-segments with activity of late-stage aftershocks or with postseismic fault healing may have relatively low b or b—-values too.We believe that once a catalog of earthquakes accurately relocated is used in calculation of seismicity parameters,it must contain the complete data of earthquakes occurring during the period and in the area studied,rather than only a part of data selected.