关键词: 汶川M_S 8.0地震, 基岩地表破裂, 映秀-北川断裂, 同震位错, 右旋斜冲运动

Abstract: During the M_S 8.0 Wenchuan earthquake,most of surface deformation zones show as flexural scarps or fault scarps,and surface ruptures in bedrock are rare.However,earthquake surface ruptures are entirely exposed in bedrock and discovered by authors near Xiaojiaqiao town of Anxian county.Based on careful analysis of the deformation characteristics and the inner structure of this rupture zone,and in combination with features of the regional earthquake surface ruptures,the authors hold that the earthquake surface ruptures are developed and extend mainly along the preexisting Yingxiu-Beichuan Fault during this earthquake,the faulting is right-reverse-slip movement at a low angle,and the maximum vertical co-seismic dislocation is 5.4 meters,which coincide with the measurements of the flexural scarps or fault scarps.

Key words: M_S 8.0 Wenchuan earthquake, surface rupture in bedrock, the Yingxiu-Beichuan Fault, co-seismic dislocation, right-reverse-slip movement