Plate motion is one of the major dynamic sources for deformation in the crust and the mantle. Since the deformation in the crust can be observed by GPS and geological observation, the comparison between the deformatio...Plate motion is one of the major dynamic sources for deformation in the crust and the mantle. Since the deformation in the crust can be observed by GPS and geological observation, the comparison between the deformation of the crust and that of the mantle becomes one of the major methods available for studying the coupling between crust movement and mantle deformation. Regional crustal strain rate tensor values in China, inferred from Quaternary fault slip rates and earthquake deformation data within areas of approximately 200×200 km, are interpolated with smooth, continuous functions (spline) to determine a self-consistent model velocity gradient tensor field for the present-day Chinese continent. In the interpolation process, GPS velocity vectors are also matched, within a defined frame of reference, by the model velocity field. The directions of shear deformation calculated from the model velocity field are compared with the fast directions of shear-wave splitting inferred from SKS phases and Pn waves. The results might represent the shear deformation in mantle and the deep crust, respectively. There is a relatively large difference between the average direction of crustal shear and that of mantle shear in the area of active tectonics, which may indicate that in these active areas the crust and the mantle may be decoupled.展开更多
文摘Plate motion is one of the major dynamic sources for deformation in the crust and the mantle. Since the deformation in the crust can be observed by GPS and geological observation, the comparison between the deformation of the crust and that of the mantle becomes one of the major methods available for studying the coupling between crust movement and mantle deformation. Regional crustal strain rate tensor values in China, inferred from Quaternary fault slip rates and earthquake deformation data within areas of approximately 200×200 km, are interpolated with smooth, continuous functions (spline) to determine a self-consistent model velocity gradient tensor field for the present-day Chinese continent. In the interpolation process, GPS velocity vectors are also matched, within a defined frame of reference, by the model velocity field. The directions of shear deformation calculated from the model velocity field are compared with the fast directions of shear-wave splitting inferred from SKS phases and Pn waves. The results might represent the shear deformation in mantle and the deep crust, respectively. There is a relatively large difference between the average direction of crustal shear and that of mantle shear in the area of active tectonics, which may indicate that in these active areas the crust and the mantle may be decoupled.
