关键词: GPS测量, 块体运动和变形, QUAD方法, 活动边界

Abstract: On the basis of carefully pre-processed GPS data observed at reference and basic stations of CMONOC (Crustal Movement Observational Network Of China) in 1998 and 2000, the coordinates in ITRF97 referenced to the epochs of 1998.6808 and 2000.4658 as well as their covariance matrices at 79 GPS stations distributed in the main tectonic blocks over China's continent are derived respectively. Under the tectonic framework of the main tectonic units and the main active blocks of China proposed by MA Xing-yuan et al. and ZHANG Pei-zhen et al., respectively, 20 major tectonic blocks in China's continent are tested and identified one by one by using an extended QUAD (Quasi-Accurate Detection of gross errors) method (HUANG Li-ren, et al., 2002). The adjacent blocks with no significant relative motions to each other are merged into one block. Thereby, the active blocks and their boundaries are identified. A model combining the rigid motion, block uniform strain and local deformation is used to describe the present-day activity and deformation of tectonic blocks in China's continent. The Euler's vector and the entire uniform deformation parameters of the blocks with significant relative motion, as well as the local heterogeneous deformation within the blocks are derived. The pattern and rate of motion on active boundaries are also calculated. Based on the afore-mentioned results, it is pointed out that the crustal motion in China's continent is much stronger in the western part than in the eastern part. In addition, the quantitative comparisons of crustal motion among the main active blocks and boundaries in the western part of China are also given. This result may provide the deformation background for the evaluation of earthquake risk regions.

Key words: GPS measurement, block motion and deformation, QUAD method, active boundary