HR: 0800h
AN: T21A-0371    [Abstracts]
TI: Continuous GPS Monitoring of Deformation along the Xianshuihe Fault, Southwest China
AU: * Shen, Z
EM: zshen@ies.ac.cn
AF: Institute of Geology, China Earthquake Admin., P.O.Box 9803 Qijiahuozi, Beijing, 100029, China
AU: * Shen, Z
EM: zshen@ies.ac.cn
AF: Dept of Earth and Space Sciences/UCLA, 595 Charles Young Dr, Los Angles, CA 90095- 1567, United States
AU: Wang, M
AF: Institute of Earthquake Science, China Earthquake Admin., 62 Fuxing Rd, Beijing, 100036, China
AU: Gan, W
AF: Institute of Geology, China Earthquake Admin., P.O.Box 9803 Qijiahuozi, Beijing, 100029, China
AU: Li, T
AF: Institute of Geology, China Earthquake Admin., P.O.Box 9803 Qijiahuozi, Beijing, 100029, China
AU: Liao, H
AF: Sichuan Seismological Bureau, Chengdu, Sichuan, 610041, China
AB: The Xiaoshuihe fault is one of the most actively deforming faults in Chinese continent. Located in the eastern boundary of the Tibetan plateau, it slips more than 10 mm/yr left laterally, and plays an important role in transforming the north-south shortening of the plateau into east-southeastward extrusion. To understand its deformation pattern and mechanism we establish a small continuous GPS network along the Xianshuihe fault to monitor its spatio-temporal deformation behavior. The network is composed of two pairs of stations straddling the central and southern segment of the fault at Daofu and Tagong respectively. More than one and a half years of data have been collected, which are processed as baselines (17 km and 34 km in length respectively) across the fault. Analysis of the daily baseline solutions shows that they are accurate at about 1 mm or better, enough to detect some transient slip on fault. Displacement time series of the station pairs reveal markedly different deformation patterns across the two fault segments: steady across the south and variant in time across the central segment. Employing a dislocation model attributing the transient deformation to slip on fault segments in the brittle-ductile transition zone in central crust, we develop a spatio-temporal slip model to interpret the data. According to the model, the central segment of the Xianshuihe fault splits into east and west branches, which slip alternatively, and the slip on the east branch migrates gradually from south to north. The transition zone of the southern segment, on the other hand, slips steadily over the entire observation period. The difference in deformation style and process between the south and central segments should reflect the evolution status of the fault zone stress/strain, associated with the history of fault rupture and fault zone rheology. The difference in kinematics among fault segments and branches may suggest higher tectonic stress and greater seismic potentials for the south than the north segment, and for the east than the west branch of the central segment of the Xianshuihe fault.
DE: 1209 Tectonic deformation (6924)
DE: 1240 Satellite geodesy: results (6929, 7215, 7230, 7240)
DE: 8111 Continental tectonics: strike-slip and transform
DE: 8123 Dynamics: seismotectonics
DE: 8159 Rheology: crust and lithosphere (8031)
SC: Tectonophysics [T]
MN: 2007 Fall Meeting