张家口-蓬莱断裂带地震构造特征的初步探讨

PRELIMINARY STUDY ON THE SEISMOTECTONIC CHARACTERS OF THE ZHANGJIAKOU PENGLAI FAULT ZONE

北西向张家口－蓬莱断裂带由近２０条北西至北西西向断裂组成，是一条对新生代区域地质构造发育起到重要控制作用的地壳构造带。断裂带新生代活动由中部向西北和东南部发展，总体表现左旋走滑性质。断裂带有山西断陷盆地带等几条北东向活动构造带与之交汇，形成北西和北东向两组断裂相互交切的构造组合，出现５个复杂的构造交接段。６级以上强震和大多数中小地震群集于这些地段，其中北西和北东向断裂都可能发生地震，显示共轭破裂错动特征，但北东向断裂发生的地震强度较大。张北－尚义６．２级地震发生于断裂带与山西断陷盆地带交接段的西缘，是断裂带向西北扩展的结果。

he Zhangjiakoupenglai Northwesttrending fault zone is an important seismotectonic zone in North China. We have done a preliminary study about its seismotectonic characters on the basis of the geological, geophsical and seismic activity data. The fault zone, which consists of nearly 20 NW-NWW trending faults, is a crust structure one which has an important controlling effect on the regional teconics of the Cenozoic Era. The fault zone is leftlateral slip on the whole. In the Palaeogene period the zone's middle part was very active, after that its northwest and southeast sections became active in the Neogene period. The fault zone merges with several NEtrending active teconic zone, so it owns a kind of tectonic combination that NW and NE trending faults intersect each other and includes 5 complex tectonic merging parts. The major earthquakes of M≥6 and most of middlesmall earthquakes assemble these parts. Both NW and NE trending fualts can cause earthquakes. So it demonstrates the character of conjugate ruptures. But the NEtrending fault can produce bigger earthquakes than those of NWtrending fault. The ZhangbeiShangyi 6.2 earthquake can be the result of northwestward extending along this fault zone.