Abstract: There are many differences of seismicities between the Zhangbei Shangyi earthquake and Datong Yanggao earthquake,although the distance is less than 150km between the epicenters of them.The conjugate directions of EW and NS are the dominant directions of the regional earthquake (M_s≥5.0) epicenter arrangement,active faults with seismic frequence anomalies,the tendency of earthquake occurence near epicenter,the long axis of seismic gap,before Zhangbei Shangyi earthquake,and distribution of aftershock epicenters.While conjugate directions of NE and NW are the dominant directions of various seismic anomalies for Datong Yanggao shock.The causes of such a direction difference may be associated with the tectonic setting and the additional stress field.

Key words: Seismic activity, DatongYanggao earthquake, ZhangbeiShangyi earthquake

摘要： 张北-尚义地震与大同-阳高地震虽然相距不远,但在地震活动性上有较大的差异。大同-阳高地震前,区域地震活动、断裂带附近微震活动、震源邻区地震活动趋势、地震活动空区展布和余震分布都与北东或北西向这组共轭构造一致;张北-尚义地震前,区域地震活动、断裂带附近微震活动、震源邻区地震活动趋势、地震活动空区展布和余震分布则与近南北或近东西向这组共轭构造平行。产生这种方向差异的原因可能是构造条件的差异以及附加应力场的不同。

关键词: 地震活动性, 大同-阳高地震, 张北-尚义地震