HR: 15:25h
AN: S42F-07    [PDF]
TI: The Effects of 3D Structure and Finite Sources on Ground Motion in the Yanhuai Basin
AU: * Wang, H
EM: haijiang@geophysik.uni-muenchen.de
AF: Theresien str 41, Institute for Geophysics. LMU, Munich, 80333 Germany
AU: Igel, H
EM: igel@geophysik.uni-muenchen.de
AF: Theresien str 41, Institute for Geophysics. LMU, Munich, 80333 Germany
AU: Wang, G
EM: wang@geophysik.uni-muenchen.de
AF: Theresien str 41, Institute for Geophysics. LMU, Munich, 80333 Germany
AB: Three dimensional finite difference earthquake scenarios from finite faults are compared with those from a point source for the 1792, Mw 6.75 Shacheng Earthquake, Beijing area, with different velocity models -- homogeneous, layered, and heterogeneous. The goal is to separate the effects of fault dimension and heterogeneity on the ground motion and shaking hazard in the study region. The kinematic finite source model is a traditional one (Hartzell, 1978), in which the rupture initiates at the hypocenter of the fault plane and propagates radially. The velocity of this propagation is assumed to be about 80 percent of the shear wave velocity. From the magnitude we can derive the geometrical parameters of the finite fault plane, assumming the shape of the fault is rectangular. Then the fault plane is divided into elements. Each element is treated as a separate point source. The scalar moments of these elements are assigned randomly with the summation equal to the total moment of the point source. We use the same gauss function for these separate elements as for the point case, with the rise time relative to the length and the rupture propagation velocity. Our comparisons are in terms of the velocity and rotation seismograms, the PGV (peak ground velocity), the PGR (peak ground rotation), the shaking duration distribution and response spectrum of velocity. Generally it is observed that the attenuation rate (both of PGV and PGR) at the area of hanging wall is higher than on the opposite side. Further preliminary findings point to (1) enhanced near-fault ground motion in the finite-fault case and (2) complex interaction between the finite fault radiation and the 3D heterogeneity.
UR: http://woerth.geophysik.uni-muenchen.de/~haijiang/abstract.pdf
DE: 7223 Seismic hazard assessment and prediction
SC: Seismology [S]
MN: 2003 Fall Meeting