【摘要】 分别建立弹性与粘弹性的分层半空间模型,利用PSGRN/PSCMP程序,模拟计算汶川地震的同震与震后位移,并与实际GPS观测资料进行了简单对比分析,进而探讨重力及粘度对同震与震后位移的影响.结果显示,低粘度模型对短期内震后位移影响较大,其造成的震后地壳运动接近4mm/yr,甚至超过龙门山断裂带两侧地块间的相对运动速率.因此,其10年尺度的差值能够反映出粘度分层对震后变形的影响,震后由于低粘度的中下地壳、地幔造成的上地壳局部运动不可忽略,这在一定程度上支持龙门山断层下的深部作用过程可能是引发汶川地震的主要因素.更多还原

【Abstract】 The co-seismic and post-seismc deformations of the Wenchuan Earthquake are calculated with the software PSGRN/PSCMP and compared with the observed GPS data. The differential displacements of the half-space elastic and viscoelastic layering models during time gaps ≤ 10 years illustrate the influence of viscosity on the post-seismic deformation. The lower the viscous crust that is chosen, the higher the postseismic deformation obtained. The crust velocity derived from the lower viscous model is ~4mm/yr, which is faster than the relative motion across the Longmenshan fault according to the GPS observation, and therefore indicates that local movements originating from the low viscous crust and mantle should not be neglected. We conclude that lower viscosity of the lower crust and mantle results in higher postseismic deformation of the upper crust. This conclusion is consistent, to some extent, with several recent studies which suggested that the Wenchuan Earthquake was mainly caused by deep processes beneath the Longmenshan fault.更多还原