利用长期GPS数据研究2008年汶川地震震后形变

Post-Seismic Deformation Associated with the 2008 Wenchuan Earthquake by Long-Term GPS Data

采用2008年汶川M_W7.9地震震后7a的GPS连续站和流动站的长期观测资料,基于粘弹性松弛模型,利用PSGRN/PSCMP程序计算汶川震后形变,反演巴颜喀拉块体下的粘弹性参数。其中分层模型考虑巴颜喀拉块体下存在低速带,最优拟合的粘弹性松弛模型显示该低速带粘弹性参数为2.51×10^(18) Pa·s,而中下地壳粘弹性参数为3.98×10^(18) Pa·s。

In this paper,we process relatively dense GPS data from continuous and campaign stations spanning over 7 years ofter the 2008 Wenchuan earthquake in the Songpan-Ganzi terrane and explore a series of viscoelastic relaxation models using the PSGRN/PSCMP program.We examined the existence of the proposed lower crust flow under the eastern Tibetan plateau.Our results show that the best-fitting steady-state viscosity of the thin low velocity zone is approximately 2.51×10^18 Pa·s,while the Maxwell viscosity of the middle-lower crust beneath the Plateau is around 3.98×10^18 Pa·s.