【摘要】 选取2009年1月至2022年12月唐山老震区的地震目录资料计算b值，利用格点搜索法确定b值下降幅度较大(≥20%)的区域作为异常区，分析该区域b值的时间变化特征，结合b值的时空变化研究该区域发生M4.0以上地震的危险性。研究发现，唐山老震区7次(组)M4.0以上地震均发生在b值下降幅度较大的区域边缘或附近，表明应力较高的区域是地震危险区。异常区域内b值的时间变化显示，7次(组)M4.0以上地震多在震前半年至一年出现b值下降的变化过程，也反映了异常区域应力逐渐积累的过程。总体来说，b值的时空下降变化对唐山老震区M4.0以上地震的研判具有指示意义。更多还原

【Abstract】 We select the data of earthquake catalogue from January 2009 to December 2022 in Tangshan old seismic region to calculate the b-value. The lattice searching method is used to determine the abnormal area with a significantly decrease in b-value(≥20%), the time variation characteristics of the b-value in this area are analyzed, the risk of M≥4.0 earthquakes in the area is studied based on the b-value spatiotemporal variation characteristics. The research has found that 7 M≥4.0 earthquakes occurred at or near the edges of areas with significantly decrease in b-values in the Tangshan old earthquake area, which indicates that areas with high regional stress are high-risk areas for earthquake occurrence. According to the time changes of b-values in the abnormal area, most of the 7 M≥4.0 earthquakes(groups) experienced a decrease in b-values from half a year to one year before the earthquake, which also reflects the gradual accumulation of stress in the abnormal area. The b-value decrease in time and space has indicative significance for the study and judgment of M≥4.0 earthquakes in the Tangshan old seismic region.更多还原