Abstract: A M 6.9 earthquake of 1981 occurred in the Daofu region in western Sichuan Province,an epicetre being siruated about 2km southeast of Daofu with an intensity of 8.On the basis of field investigations,including structural conditions,recent crustal movement and tectonic stress fields of the seismic region alongwith ground fractures,isoseis-mals,ground motions,aftershocks,focal mechanism solutions and geodetic observations,the Authors incline to consider that the event in question is caused by sinistral motion of the Xianshuihe fault under the action of nearly EW-trending tectonic stress field.Also discussed in this paper are locking of the fault and migrating of earthquakes along the northern segment of the fault.

摘要： 本文以1981年1月24日道孚6.9级地震的宏观考察资料为基础,从震区地质构造条件、近代地壳运动与构造应力场特征出发,结合这次地震地裂缝展布特征、等烈度线形态、地震时的地面运动、余震序列及震源错动特征及地壳形变资料的综合分析,认为此6.9级地震是在区域性近东西向的压应力作用下,使活动强烈的鲜水河断裂再次发生左旋错动的结果。并着重讨论了道孚地震区的闭锁条件以及鲜水河断裂北面地震的迁移过程。