利用玉树震后地质调查获取的地表破裂位移,参考余震精定位结论以及地震波和InSAR反演结果,构建了玉树MS7.1地震发震断层模型。基于弹性-粘弹分层介质模型中平面矩形位错理论,考虑介质自重的影响,模拟了玉树地震同震形变和重力变化。图像显示,玉树绝对重力点刚好位于同震重力变化极值附近,变化量达到25.02×10-8m·s-2。通过对震前重力变化以及对两台FG-5绝对重力仪的一致性进行讨论,认为实测玉树台27.2×10-8m·s-2为同震重力变化,这与基于位错理论的同震模拟结果一致,是对位错理论近场变化的1次很好的验证。

Abstract Using the conclusion of aftershocks relocation, inversion on seismic wave and InSAR results, and surface rupture displacement obtained by geological survey after the earthquake, this paper constructs a faults model of Yushu MsT. 1 earthquake. Based on rectangular dislocation theory in elastic-viscoelastic layering medium, we have simulated the co-seismic deformation and gravity change with gravitational effect considered. The pictures show that the absolute gravity measuring point is beside the extremum of coseismic gravity change, and the numerical value reach to 25.02 × 10-Sm·s-2. After a discussion about the gravity changes before the earthquake and the coherence consistency between two FG-5 absolute gravimeters, we think that the measured value 27.2 × 10-Sm·s-2 at Yushu station is coseismic gravity change. It＇s coincident with the simulation results based on dislocation theory. So it＇s good inspection to the near-field changes on dislocation theory.

国家自然科学基金（41104049）、中国地震局青年震情跟踪课题（2012020207）、地震行业科研专项（201008001）、中国地震局玉树地震综合科学考察（2060302）共同资助