HR: 0800h
AN: S31A-1030    [Abstracts]
TI: Computation of Strong Ground Motions using Modified Empirical Green's Functions
AU: * Jo, N
EM: endyjo@seismic.snu.ac.kr
AF: School of Earth and Environmental Sciences, Seoul National University, San 56-1, Sillim9-dong, Gwanak-gu, Seoul, 151-747 Korea, Republic of
AU: Baag, C
EM: baagce@snu.ac.kr
AF: School of Earth and Environmental Sciences, Seoul National University, San 56-1, Sillim9-dong, Gwanak-gu, Seoul, 151-747 Korea, Republic of
AB: We simulated strong ground motions using empirical Green's functions (EGF) containing information of amplification and attenuation of a specific site. The EGF is the seismic data observed from small earthquakes, such as foreshocks or aftershocks. The main shock can be predicted with EGFs using the finite fault model. The conventional method based on EGF did not consider locations of subfaults. Same EGF has been applied to all subfaults on the fault plane. Green's functions computed for shallow sources and deep sources, however, are not similar to each other. So, it is need to modify the EGF considering the depth of subfaults and epicentral distances. For modifying the EGF, we computed the theoretical Green's function using the wavenumber integration method in layered medium, and deconvolved the EGF with the TGF for each subfault. In order to compute the strong ground motions, we used the finite fault model with 2-asperity based on Somerville et al. (1999). This model was produced considering some empirical relations for large earthquakes. The slip contrast between asperity and other area of the fault plane was fixed to 2. We used the velocity structure proposed by Chang and Baag (2004) in Korea. After computing the TGFs using the wavenumber integration method and constructing the TGF database around the source area in advance, we simulated strong ground motions using this TGF database. This method was applied to the large earthquakes of the world for the verification. The ground motions at seismic stations in southeastern Korea for Mw 7 were properly simulated using modified empirical Green's function method in layered medium. The proposed method and fault model for estimation of site dependent seismic parameters and ground motions could be efficiently used in the low and moderate seismicity regions.
DE: 7223 Seismic hazard assessment and prediction
DE: 7209 Earthquake dynamics and mechanics
DE: 7212 Earthquake ground motions and engineering
DE: 7215 Earthquake parameters
SC: Seismology [S]
MN: 2004 AGU Fall Meeting