GPS monitoring of the crustal motion in southwestern China

Through GPS carrier phases observation in southwestern China during 1991-19 97, the velocity field within eastern Qinghai-Xizang (Tibet) and its neighb our regions has been established. The velocity of those sites in and west o f Chuan-Dian block is mostly 5-10 mm . a(-1) relative to the fiduciary stat ion CHDU (Chengdu), and the motion in Chuan-Qing and Yangtze blocks east of the Xianshuihe-Xiaojiang fault is weak with a velocity of about 0-7 mm . a (-1). The velocity vector in these areas indicates a clockwise rotation vor tex rather than the so-called intensive eastward pushing or eastward escape . The main pattern of the crustal deformation is a clockwise rotation vorte x structure and a differential slip along the boundary fault between differ ent blocks.