【摘要】 2008年汶川8.0级地震沿龙门山断裂带内的映秀—北川断裂和灌县—安县断裂产生了近300 km的同震地表破裂带。震后地质科学考察发现地表变形以逆冲为主,并伴有右旋走滑。地震地表破裂带大多沿古生代碳质泥岩、页岩和三叠系煤系地层内的滑动面出露地表,这些软弱地层为地震破裂带冲到地表提供了超低摩擦滑动带。我们发现在同震垂直和水平位错达6m左右的地表破裂带,地震的同震滑动发生在厚度约0.5～2cm的狭窄滑动带内,以发育新鲜的灰色断层泥为特征,这些断层泥是地震断层快速滑动过程中岩石—流体相互作用的结果。更多还原

【Abstract】 Intensive coseismic surface deformation was produced by the 12 May 2008 Wenchuan Ms 8.0 earthquake along the pre- existing NE-trending Yingxiu-Beichuan and the Guanxian-Anxian faults,in the Longmen Shan fault zone.The post-earthquake geological investigation shows that the most of surface ruptures occurred along the carbonaceous argillite,shale and coal-bearing layers, which are low-frictional layers to form slip interface within the fault zone.We found that fresh fault gouges with a thickness of 1～2 cm occurred along the co-seismic surface rupture zone,which suggests that the coseismic slip concentrated in a narrow slip zone of thickness ranging from 0.5～2 cm although the coseismic vertical and horizontal dislocations are larger than 6 meters.These fresh fault gouges within co-seismic slip zone are resulted from both thermal pressurization and frictional melting during rapid faulting movement at the shallow crust level.更多还原