中文摘要：

以汶川地震前后GPS观测得到的同震形变场为约束,利用带约束的最小二乘反演方法,分别反演考虑与不考虑滑脱层的最优同震断层滑动模型,并在此基础上正演了同震重力变化。结果表明,含滑脱层的断层滑动模型模拟的GPS台站的同震水平形变和重力台站的同震重力变化都更接近实际的观测结果,证实龙门山的中央断裂带南段存在大规模的近水平的滑脱层参与了汶川地震的同震滑动。

英文摘要：

By using the least-square method constrained by the co-seismic deformations of the Wen- chuan earthquake derived from GPS, we inverse the slip models, with and without considering ramp- decollement separately. Based on the slip models obtained, we simulate the co-seismic gravity chan- ges. The results show that the co-seismic horizontal deformation of the GPS stations and the gravity changes of the gravity stations modeled by the slip model with ramp-decollement are both closer to the actual measurements. This verifies that a large-scale nearly horizontal ramp-decollement,which exis- ted at the southern part of the mid-fracture of the Longmenshan, has participated in the co-seismic slip of Wenchuan earthquake.