地震地表破裂基本参数是反演地震破裂过程的基本约束条件和预测其他活动断层地震危险性不可缺少的物理量.以野外地表破裂带重要观测点全站仪或差分GPS仪实测数据为基础,结合高分辨率遥感资料解译、先存断层陡坎构造地貌标志的识别、以及地形测绘资料的考证等,重新论证了5·12汶川地震地表破裂带展布样式、长度、最大同震位移值等基本参数.结果表明,地震地表破裂带长度可达240 km,最大垂直位移为6.5±0.5 m,最大右旋走滑位移4.9 m,基于倾角向下变缓逆断层模型推测汶川地震在龙门山推覆构造带中段产生了最大~7 m的地壳缩短量,说明青藏高原东缘横向逆断层为将高原内部东向水平运动转换为高原隆升的转换构造,这一研究结果有助于深化认识青藏高原东缘隆升机理.

Parameters of earthquake surface ruptures are fundamental constraints for earthquake rupture process inversion and for seismic risk assessment of similar active faults. Based on in-situ measurements at the key observation sites along the earthquake surface ruptures using Total Stations and differential GPS receivers, interpretation of high resolution satellite images and tectonic landform analysis for preexisting fault scarps, the parameters, such as rupture length and its maximum offsets, of the 5·12 Wenchuan earthquake surface rupture zone are reassessed. The results indicate that its length reaches 240 km and the maximum coseismic vertical offset is ~6.5 m measured at north Qushan Town, while its right-lateral slip is ~4.9 m at south Pingtong Town. The maximum vertical offset corresponds to a crustal shortening of ~7 m, and this implies that structural transformation from crustal shortening in the Longmenshan to the uplift along the Longmenshan thrust belt may be responsible for the growth of high topography along the eastern margin of the Tibetan Plateau.