Abstract:Based on postearthquake field investigation, we summarized the distribution, occurrence, inherited reactivation and deformation features of the coseismic surface ruptures developed on the Longmenshan fault system, together with the relationship between coseismic deformation and earthquake geological hazards. Systematic research indicates that the surface rupture occurred simultaneously along the BeichuanYingxiu fault and the AnxianGuanxian fault; the former is 275 km long and characterized by high angle thrust and dextral strikeslip, while the latter is 80km long and characterized by flat thrust. Further analysis also reveals the inner relations between segmentation of coseismic surface rupture and zonation of surface damage associated with the Wenchuan earthquake. Surface damages and earthquake geological disasters are affected directly by the occurrence of coseismic surface rupture zone, for example, damages and hazards developed along the high angle BeichuanYingxiu thrust fault are much more serious than that along the flat AnxianGuanxian thrust fault. As for various seismic faults, the degree of surface deconstruction and geological disaster produced by thrusttype seismic fault with vertical motion is higher than that by strikesliptype seismic fault with horizontal motion. Therefore, the relation between the earthquake geological disasters and the rupture process of the Wenchuan earthquake together with the associated coseismic surface deformation need further study.