Recent Crustal Deformation and Strain Accumulations in Continental China Inferred from GPS and Seismicity Data

This work analyzes recent crustal deformation and strain accumulations in continental China based on GPS and seismicity data. Since the early 1990s, several regional GPS networks for active tectonic studies were established in continental China. All of these networks were surveyed in campaign mode at one to two year intervals and have been conducted on a scale ranging from several hundred kilometers to a few of thousands kilometers. Each individual network was originally designed to address local problems without attempting to measure the large-scale deformation of continental China, and therefore can’t be merged together seamlessly, due to different data analysis strategies involved, to yield a uniform velocity field (Bannette, et al., 1999). The only realistic approach for a large-scale GPS solution to date is to merge the original observations from different regional networks into a coherent solution. According this strategy, a uniform velocity field in 1TRF97 frame on continental China scale was obtained (Wang, et al., 2001). It appears that Tibetan Plateau itself absorbs most of the deformation caused by collision and penetration between India and Eurasia. More than 80% of the relative motion is accommodated by convergence within the Plateau. The North China and South China blocks, east of the Tibetan Plateau move coherently at a rates of 10 to 14 mm/yr with respect to the stable EurasiaWe perform a joint inversion of seismicity data and 338 GPS velocities in continental China for a self-consistent velocity field, strain rate field. The model velocity field is expanded as bi-cubic spline interpolation functions defined within a 2° × 2° grid that covers the country and extends into the assumed rigid India and Eurasian plates to south and north. The inversion jointly minimizes the magnitudes of fitted strain rates and the misfit to the observed velocity data. The spline technique allows high spatial resolution of strain rate variations, especially in regions with spatially dense GPS data. Our results show that the maximum strain rate is located along the South-North tectonic zone, Chuan-Dian block, these are the most intensive neotectonic deformation areas in continental China.