HR: 0800h
AN: S31B-0442    [Abstracts]
TI: Simulation of Long-Period Ground Motions in the Southern Korean Peninsula for Validation of a Three-Dimensional Velocity Model
AU: * Kang, T
EM: tskang@kigam.re.kr
AF: Korea Institute of Geoscience and Mineral Resources (KIGAM), 92 Gwahak-ro, Yuseong- gu, Daejeon, 305-350, Korea, Republic of
AU: Shin, J
EM: jinsoo@kigam.re.kr
AF: Korea Institute of Geoscience and Mineral Resources (KIGAM), 92 Gwahak-ro, Yuseong- gu, Daejeon, 305-350, Korea, Republic of
AB: Recent advances on the understanding of the crustal structure in the southern Korean peninsula have elucidated the importance of path effects on ground motion from explosion sources and natural earthquakes occurred in and around the region. A three-dimensional velocity model of the region is constructed from studies based on the receiver-function analyses of broadband seismograms and the tomographic inversion of surface-wave Green's functions from cross-correlation of short-period ambient noise between pair of accelerograph stations. In order to evaluate the adequacy of the velocity model, we simulate ground motion velocity from the 20 January 2007, Mw 4.5, Odaesan, Korea, earthquake using the three-dimensional finite-difference method. The simulated ground motions are compared with the recorded motions at 23 broadband seismograph stations in the frequency band of 0.1-0.3 Hz. Our crude model for the sourthern Korean peninsula generally estimates well the long-period peak ground motion and dominant waveforms of the recorded motions. In the long period larger than about 3 seconds, the waveform and amplitude of S waves are similar to those of observed seismograms. Developments of P waves and coda of S waves are weak in the simulated seismograms compared to the recorded seismograms. This is because that most of the velocity model volume is based on the three-dimensional interpolation of one- dimensional velocity profiles obtained from receiver function analyses of sparse observation locations, which may have a smoothing effect on the real structure. The simulation also emphasizes the importance of the uppermost crustal structure above about 3 km depth believed to be highly heterogeneous as well as to be trapping most of S-wave energy. Future seismic explorations covering the entire southern Korean peninsula will improve the resolution of our model.
DE: 7205 Continental crust (1219)
DE: 7212 Earthquake ground motions and engineering seismology
DE: 7290 Computational seismology
SC: Seismology [S]
MN: 2007 Fall Meeting