HR: 1330h
AN: S52A-0124    [PDF]
TI: Simulation of Strong Ground Motion by Dynamic Rupture With Locally Variable Time-Step Finite-Difference Method
AU: * Kang, T
EM: tskang@seismic.snu.ac.kr
AF: School of Earth and Environmental Sciences, Seoul National University, San 56-1, Sillim-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, Sillim-dong, Gwanak-gu, Seoul, 151-747 Korea, Republic of
AB: Characteristics of strong ground motion depend on the complicated processes of earthquake rupture along fault surface, propagation path, and site conditions. The earthquake rupture includes dynamic processes of rupture nucleation, propagation, and healing that are governed by friction properties on the fault. Seismic wavefield radiated by the fault processes propagates through the heterogeneous geological media and undergoes near-surface modulations such as either amplification or deamplification. Complete understanding of these effects requires a numerical modeling technique with multi-scale resolution. That is, a high resolution modeling with dense grid and time steps is required in the vicinity of the fault rupture in order to deal with the dynamic rupture processes. On the other hand, modeling of the wavefield propagating through the media outside the rupture zone requires relatively low resolution. However, even in the latter case, large velocity contrast between the media such as sedimentary basins surrounded by host rock forces modeling parameters to be discontinuous in order to avoid an oversampling in both time and space. Recently, we proposed a 3-D fourth-order staggered-grid finite-difference technique combining discontinuous grids with locally variable time-step (LVTS). Discontinuity of modeling parameters is generalized in full three-directions; thus a region of modeling parameters with fine scale can be localized within a domain, and/or the boundary between the regions can be extended to the free surface. These properties allow the LVTS scheme to be efficiently used for modeling of both rupture dynamics and radiated wavefield in the heterogeneous media. Simulation results of earthquake ground-motion including high-resolution rupture dynamics are presented. This approach makes possible to understand the combined effect of dynamic fault processes and heterogeneous media surrounding the fault region. Also, if this type of simulation results is compared with observed data, it will provide a better understanding for the physical conditions influencing source dynamics from ground-motion records.
DE: 7209 Earthquake dynamics and mechanics
DE: 7212 Earthquake ground motions and engineering
DE: 7223 Seismic hazard assessment and prediction
DE: 7260 Theory and modeling
SC: Seismology [S]
MN: 2003 Fall Meeting