CONTEMPORARY HORIZONTAL TECTONIC DEFORMATION FIELDS IN CHINA INVERSED FROM GPS OBSERVATIONS
Yang Shaomin, You Xinzhao, Du Ruilin, Qiao Xuejun and Wang Qi\;(Institute of Seismology,CSB,Wuhan 430071)\;
Assuming that the contemporary tectonic activity in China can be treated as continuous. We have simulated 412 present day multiple epoch Global Positioning System (GPS) velocity solution in China with a bi cubic spline interpolation function to inverse the self consistent horizontal velocity and strain rate fields in China.The modelling results show that the collision of the India Plate with the Eurasia Plate is the main driving force causing crustal horizontal deformation of China. The shortening and uplift on a large scale is due to the deep underthrusting of India into beneath the Tibet at Eastern Himalayan Syntaxis.In the modelling velocity field,about 85 percent of India's convergence with Eurasia is absorbed by crust, or lithosphere thickening,especially the quick north south shortening along Himalaya and the slow E W extension within the Qing Zang Plateau.In the east central Tibet,the E W extension rate is up to (16±2.0) mm/a and torsion clockwise is in evidence.India moves relatively to Eurasia about a pole of rotation at (29.7°N, 19.3°E 0.392°/Ma),south China block moves at(11±1.54)mm/a in the direction of (102°±7.4°) with the pole position(62.25°N,126°E,0.141°/Ma).The Tarim Basin is stable relatively,the velocity of west area to Tarim is higher than that of the east,rotates clockwise.In general,the movement direction of China continent is N E and in a radiation status.The N S compression rate across Himalaya and the Qing Zang Plateau is (19±2.0) mm/a (13±1.5)mm/a at western Tianshan tectonic belt and (6±1.4)mm/a at eastern Tianshan tectonic belt.The left lateral strike slip rate of the Altyn Fault is (6±1.2)mm/a.