HR: 0800h
AN: S31A-1029    [Abstracts]
TI: A Hybrid Method for the Generation of Broadband Ground Motions
AU: * Askan, A
EM: aaskan@andrew.cmu.edu
AF: Carnegie Mellon University, Civil and Environmental Engineering Department, Computational Seismology Laboratory, 5000 Forbes Avenue, Pittsburgh, PA 15213 United States
AU: Bielak, J
EM: jbielak@cmu.edu
AF: Carnegie Mellon University, Civil and Environmental Engineering Department, Computational Seismology Laboratory, 5000 Forbes Avenue, Pittsburgh, PA 15213 United States
AB: A hybrid method for simulating broadband ground motions is presented. The low frequency ground motions are generated deterministically using the 3D finite-element method whereas the high frequency motions are obtained stochastically. The technique for calculating the high frequency components involves the methodology by Irikura (1983) and Kamae et al. (1996) for superposition of stochastic Green's functions for small events over sub-faults. One major modification is made in order to include a more realistic frequency-dependent radiation pattern. We incorporated the theoretical double-couple full-space radiation pattern for intermediate frequencies and used the average radiation factor proposed by Boore for the higher frequencies. In order to be able to better represent the near field ground motions, the corrections for the amplification due to surface layers and site-dependent factors are also applied in the technique. Finally, the low and high frequency simulations are combined via a matched pair of filters eliminating the higher and lower frequency components from the motions obtained with the deterministic and stochastic methods, respectively. The proposed hybrid method is tested for the 1994 Northridge earthquake. The results are presented in the form of ground motion simulations in the Sherman Oaks region and compared with observed data.
DE: 7223 Seismic hazard assessment and prediction
DE: 7260 Theory and modeling
DE: 7200 SEISMOLOGY
DE: 7212 Earthquake ground motions and engineering
SC: Seismology [S]
MN: 2004 AGU Fall Meeting