张北6.2级地震与强震成组活动

通过利用构造块体或组孕震、成组活动模型及理论方法分析和研究了华北北部自８０年代以来发生的大同－阳高６．１级、包头６．４级和张北６．２级强震成组活动特征，结合地质构造特点及一该区历史强震活动特征的地比研究，探讨了张北地震孕育，发生的物理模型和某些震兆特征。指出，１９９８年１月张北６．２级地震是８０年代末以来华北北部强震成组活动中－重要事件。与１９８９年大同６．１级、１９９６年６．４级地震构成一个强震

ON GROUP FEATURES OF STRONG EARTHQUAKES:THE ZHANGBEI EARTHQUAKE WITH MS 6.2

Group features of the strong shocks in North China are studied in this paper based on a seismogenic model for group shocks and the theory of the group events developed by Li Qingzu et al. The events used include the Datong Yanggao shock ( M S 6.1), the Baotou shock ( M S 6.4) and the Zhangbei shock ( M S 6.2). Combined the geological structures with the recorded historical events, the model for the seismogenesis and occurrence of the Zhangbei earthquake and some precursors before it are analyzed. Research shows that the M S 6.2 shock occurred in Zhangbei in January of 1998 is a very important event among the group events in North China, which is in a same group with the Datong earthquake ( M S 6.1, 1989) and the Baotou earthquake ( M S 6.4, 1996). The main active area for this group of large shocks is along the mid western segment of the Yinshan Yanshan seismic belt in North China. The frequency of shocks and the precursors in earth resistivity show that the crust in this area changed as a whole within that time interval.