关键词: 潜在震源区, 发震构造特性, 地震危险性分析

Abstract: Studies of the properties of seismogenic structures play an important role in delineation of potential earthquake source and in determination of parameters of seismic activity. The location,direction,size and the maximum potential earthquake magnitude of a seismogenic structure can be used separately to determine the location,direction,extent and upper limit magnitude of the related potential earthquake sources. The recurrence behavior of large earthquakes on seismogenic structures is closely related to the estimation of the annual average occurrence of the high magnitude grade earthquakes. In consideration of the spatial heterogeneity of seismicity,two-grade delineation of potential earthquake source has been adopted in seismic hazard assessment in China since the late 1980s. Moreover,a relatively large region is usually taken as the seismictiy statistical unit (seismic region or seismic zone) in order to gain sufficient seismic data,so that it might contain some seismotectonic blocks with different background earthquake magnitudes. For the sake of more reasonable seismic hazard assessment,it is necessary to consider these seismotectonic blocks as the second grade potential earthquake sources,which are then subdivided into the third grade potential earthquake sources. On the basis of research on the recurrence behavior of large earthquakes on seismogenic structures,this paper proposes a method for calculating the annual average occurrence of the high magnitude grade earthquakes by applying the equivalent probability transferring in the predicted time scale. This method may greatly enhance the reasonability of seismic risk assessment. The frequency insufficiency of the second grade magnitude earthquakes of potential earthquake sources and the spatial inhomogeneity of seismogenic structures,as well as their applications to determining the parameters of potential earthquake sources are also discussed in this paper.

Key words: potential earthquake sources, properties of seismogenic structures, seismic hazard assessment