HR: 0800h
AN: T41A-05    [Abstracts]
TI: Detailed Shallow Structure of the Kunlun Fault Zone in Northern Tibetan Plateau, China: Implications from the 2001 Ms 8.1 Kunlun Earthquake
AU: * Wang, C
EM: a37171@hotmail.com
AF: China Earthquake Administration, Institute of Geophysics, Beijing, 100081, China
AU: Mooney, W
EM: mooney@usgs.gov
AF: U.S. Geological Survey, 345 Middlefield Rd. MS 977, Menlo Park, CA 94025, United States
AU: Ding, Z
EM: a37171@hotmail.com
AF: China Earthquake Administration, Institute of Geophysics, Beijing, 100081, China
AU: Yang, J
EM: a37171@hotmail.com
AF: China Earthquake Administration, Institute of Geophysics, Beijing, 100081, China
AU: Yao, Z
EM: a37171@hotmail.com
AF: China Earthquake Administration, Institute of Geophysics, Beijing, 100081, China
AU: Lou, H
EM: a37171@hotmail.com
AF: China Earthquake Administration, Institute of Geophysics, Beijing, 100081, China
AU: Chan, W
EM: chan@multimax.com
AF: Multimax Inc., 1441 McCormick Dr., Largo, MD 20774, United States
AB: A detailed shallow structure of the Kunlun fault zone (KLFZ) was jointly deduced by the CDP stacking profiles, seismic refraction sounding profiles and the records of explosion-excited trapped waves which were conducted after the 2001 November 14, Ms 8.1 Kunlun earthquake in the northern Tibetan plateau. The shallow CDP stacking sections indicate that the rupture zone with high dip-angle (about 85 degrees) extends from the surface to a depth of 100 m. Seismic phases on the on-line record sections along the fault zone were analyzed, and 1-D P- and S- wave velocity models of shallow crust within the fault zone were determined by use of the seismic refraction method. The trapped waves on three-component seismic record sections along the profile perpendicular to the fault zone were simulated with the 3-D finite difference algorithm, where the primary 3-D model was constructed based on 1-D P- and S- velocity models within the fault zone, apparent velocities of P and S phases outside fault zone, dispersion of surface waves and Q-value estimation. With the trial and error method, the 3-D shallow structure of KLFZ was refined to a five-layer model with a low-velocity zone along the rupture trace on surface. Synthetic modeling indicates that the width of the low-velocity zone is approximately 300 m in the upper four layers (with thickness 1000 m), and 250 m in the fifth layer (semi-infinite). Due to the station deployment not being dense enough, the uncertainty of estimation of fault-zone width is large (probably up to 75 m). Shear wave velocities in the fault zone are reduced by 45-30% from surrounding rocks from the surface to a depth of 5 km. The low-velocity and low-Q zone in the KLFZ model is a result of major dynamic rupture in the 2001 Ms 8.1 Kunlun earthquake.
DE: 8110 Continental tectonics: general (0905)
DE: 8118 Dynamics and mechanics of faulting (8004)
DE: 8123 Dynamics: seismotectonics
DE: 8155 Plate motions: general (3040)
DE: 8175 Tectonics and landscape evolution
SC: Tectonophysics [T]
MN: 2007 Joint Assembly