关键词: 汶川8.0级地震, 地表破裂, 中央断裂, 端部破裂(变形)特征, 青川

Abstract: The kinematic property of the Wenchan earthquake's surface rupture changes from strike-slip with slightly smaller dip-slip component to the dominant dextral strike-slip at the northeasternmost region between Shikan in Pingwu county and Woqian in Qingchuan county,where,the dip-slip component is reverse between Shikan and Pingxi,normal at Kuangpingzi and its north,with no compressive deformation observed,and it turns to dextral strike-slip near Woqian.The width of the surface deformation zone is less than 10m on this segment.At Dongjia,a village north of Woqian in Qingchuan,the seismic surface rupture zone mainly exhibits as extensional fissures and graben-like negative landform,which are the products of accommodation of the heterogeneous stress and strain at the tip portion of the seismic surface rupture.The width of the surface deformation zone is about 10～12m.No surface rupture evidence was found at Donghekou village in Qingchuan county,so we infer that the surface rupture zone didn't spread through the Qingshui River flowing along the three villages of Donghekou,Guanzhuang and Liangshuijing in Qingchuan county and the structural geomorphology reflects variant vertical motion.Evidence for dextral strike-slip motion was hardly found.The whole length of the rupture zone on the central fault is around 240km.In the course of the Wenchuan earthquake,the tectonic deformation on the surface along the central fault was adjusted within the range of the central fault,and didn't transfer to the external regions.

Key words: Wenchuan M_S 8.0 earthquake, surface rupture, the central fault, rupture(deformation)at tip portion, Qingchuan