地震不仅会产生衰减震荡的地震波，同时也引起地球产生瞬时的同震以及长期的震后形变，该形变能够被目前高精度的大地测量技术，如GPS、GRACE等准确地识别出来。相对于瞬时的弹性同震形变，震后形变的诱因非常复杂。目前普遍认为孔隙弹性回跳、粘弹性松弛和震后余滑是导致震后形变的三种主要的力学机制。因此对其产生的震后形变时空变化特征的准确模拟一直是地震学和大地测量学的热点和难点问题。本项目拟整合孔隙弹性与粘弹性变形理论，利用传统的球谐函数展开理论以及对应性原理，构建孔隙粘弹性地球的点源位错理论。在此理论框架下研究上述三种力学机制引起的震后形变的时空变化特征；并结合GPS、GRACE等大地测量观测资料，分析导致观测到的震后形变的不同作用机制及其影响量级，最后对地震断层滑动模型和地球流变结构提供有效的约束。

Earthquakes not only give rise to the oscillating seismic waves which decay eventually, but also cause both transient co-seismic and long-term post-seismic deformation, respectively. This deformation can be accurately detected by the present high-precision geodetic techniques, e.g. GPS and GRACE. Unlike that of the transient elastic co-seismic deformation, the origin of the post-seismic deformation is much more complicated. At present, it is commonly acknowledged that poroelastic rebound, viscoelastic relaxation and after slip are the three main mechanisms which are responsible for the post-seismic deformation. As a result, the precise simulation on space-time characteristics of the post-seismic deformation is always a hot but difficult issue in seismology and geodesy. This project is about to integrate the theories of poroelasticity and viscoelasticity to construct the point dislocation theory for a poroviscoelastic Earth, in which the traditional spherical harmonic function method will be applied. In this theorectical framework, the space-time characteristics of the post-seismic deformation due to the above-mentioned three mechanisms will be investigated. With the available GPS and GRACE observations after large earthquakes, the causes and the corresponding magnitudes of the deformation will first be analyzed and the fault slip models and the Earth’s rheological structures will then both constrained simultaneously.