【摘要】 本文主要根据作者的野外地震地质调查，从震区地质构造条件与构造应力场特征出发，根据库仑———莫尔剪破裂准则计算，结合这次地震地表破坏特征和等烈度线形态特征综合分析认为，在北北西至近南北向主压应力作用下，丽江７０级地震是玉龙雪山山前断裂活动的结果，地震时断层活动以倾滑为主，伴有一定的左旋扭动。并讨论了山前断裂的闭锁条件更多还原

【Abstract】 Starting from the geoloical tectonic conditions and the features of tectonic stress field in the seismic area, on the basis of the field seismogelogogical survey made by the authous and the calculation using Coulomb-Mohr failure criterion, the autous, through comprehensive analysis in combination with surface damage features and the forms of coseismic line for the earthquake, think that the M 7 0 Lijiang earthquae is a result of the activity of the piedmont fault of Yulong snow mountain under action of principal pressure stress in NNW-near NS; the fault activity in the eartquake took dip-slip as dominant, accompanying some left-lateral torsion movment And also, the locked conditions of the piedmont fault are discussed in the paper更多还原