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引言 在缺乏大震重复时间记录的情况下,根据仪器记录的地震活动测定以断层滑动发生的地壳形变分量,带有很大的不确定性。描述历史地震活动的资料可以减少这种不确定性。在日本和美国,已经注意到地震矩(M_0)和地震烈度的面积分布之间的系统联系(Hanks等人,1975;Herrmann等人,1978;Wesnousky、等人,1982)。这两个参数之间的关系,为测定历史地震的地震矩提供了一个简单而实用的方法。我们收集了公开发表的各种资料,并且测定了中国修正麦加利地震烈度为Ⅵ和Ⅷ的地震的M_0和有感范围的关系。利用所得到的这个关系,测定了过去700年发生在华北鄂尔多斯断决边缘历史大震(M>6.5)的M_0(图1和图2)。根据这些地区第四纪断层的走向和位移,推导出了这些历史地震的震源参数。然后,利用地震矩与地壳应变的关系式(Kostrov,1974;Molnar,1983)测定了
INTRODUCTION In the absence of records of large earthquake repetitions, there is considerable uncertainty regarding the determination of crustal deformation components that occur as a result of fault slippage based on seismic records recorded by the instrument. Information describing historical seismic activity can reduce this uncertainty. In Japan and the United States, a systematic connection between the seismic moment (M_0) and the area distribution of seismic intensity has been noted (Hanks et al., 1975; Herrmann et al., 1978; Wesnousky et al., 1982). The relationship between these two parameters provides a simple and practical method for measuring the seismic moment of a historical earthquake. We collected a variety of published information and determined the relationship between the M_0 and the range of sensations of the earthquakes of Ⅵ and Ⅷ in China amended by the Mecca earthquake. Using this relationship obtained, M_0 (Fig. 1 and Fig. 2) for the past 700-year historical earthquake (M> 6.5) at the edge of the Ordos Fault in North China was measured. According to the strike and displacement of Quaternary faults in these areas, the source parameters of these historical earthquakes are deduced. Then, using the relation between seismic moment and crustal strain (Kostrov, 1974; Molnar, 1983)