We obtain a unified horizontal velocity field of continental China and vicinity through measurements at 81 GPS stations provided by the National Key Infrastructure Project, Crustal Movement Observation Network of China. The velocity field delineates patterns of movements and deformation of active crustal blocks in continental China under the Eurasia-fixed reference frame. The space-based geodesy also clearly shows for the first time the horizontal movementand deformation of continental China induced by indentation of the Indian plate. The data provide kinematic constraints for simulating dynamic process of continental litho-spheric deformation.
MA Zongjin, CHEN Xinlian, YE Shuhua, LAI Xian, WEI Ziqing, CHEN Junrong, NING Jinsheng, XU Huoze & DING Guoyu1. Insitute of Geology, China Seismological Bureau, Beijing 100029, China
The coseismic Coulomb stress change caused by fault interaction and its influences on the triggering and delaying of earthquake are briefly discussed. The Xianshuihe fault belt consists of Luhuo, Daofu, Kangding, Qianning and Ganzi fault. Luohuo (MS=7.6, 1973)-Kangding (MS=6.2, 1975)-Daofu (MS=6.9, 1981)-Ganzi (MS=6.0, 1982) earthquake is a seismic sequence continuous on the time axis with magnitude greater than 6.0. They occurred on the Luhuo, Kangding, Daofu and Ganzi fault, respectively. The coseismic Coulomb stress changes caused by each earthquake on its surrounding major faults and microcracks are calculated, and their effects on the triggering and delaying of the next earthquake and aftershocks are analyzed. It is shown that each earthquake of the sequence occurred on the fault segment with coseismic Coulomb stress increases caused by its predecessors, and most after-shocks are distributed along the microcracks with relatively larger coseismic Coulomb stress increases resulted from the main shock. With the fault interaction considered, the seismic potential of each segment along Xianshuihe fault belt is reassessed, and contrasted with those predicted results ignoring coseismic Coulomb stress change, the significance of fault interaction and its effect on triggering and delaying of earthquake are emphasized. It is con-cluded that fault interaction plays a very important role on seismic potential of Xianshuihe fault belt, and the maximal change of future earthquake probability on fault segment is up to 30.5%.
