Abstract: Through the mapping on the large scale and measurement in the epicentral area of the Haiyuan earthquake, left-lateral displacements of the gullies of various kinds which cross the earthquake fault are found. The data show that the larger the gullies are, the larger the horizontal displacements. Among these displacements, there are 73 offsets of small gullies and farming banks which were formed in the earthquake of 1920 (M= 8.5) with the maximum of about 10m.Displacements of various gullies are relatively large between the Yanghuzhang valley and the Gudunzi valley.On the basis of displacements of gullies on the second terrace, initial time of offseting as well as the average and maximal displacements associated with a great earthquake, we have calculated the slip rate and seismic recurrence for 8.5 earthquakes along the studied fault.

摘要： 通过对海原地震震中区(唐家坡村西—乱堆子东)的大比例尺实测填图,获得了地震断层带上各类冲沟左旋位移的若干数据。规模越大的冲沟位移数据也越大。其中73条小冲沟和田埂的位移均为1920年8.5级大震一次造成,最大位移达10米。 从杨户章沟到古墩子之间的西华山北缘断裂,各类冲沟位移量都较大。根据发育了两级阶地的冲沟的平均位移量、位移开始的时间、大震造成的最大位移及平均位移,计算了该段断层的滑动速率和8.5级大地震的重复率。