ALBERT

Description: The simulation of realistic ground motions associated with large earthquakes is of utmost importance for engineering concerns, for example, in testing the seismic performance of buildings. It is also needed to estimate the level of ground shaking for future earthquakes. In this paper, we focus on two aspects of ground-motion modeling. First, we use deterministic wave propagation for the entire frequency range but account for source variability by implementing self-similar slip distributions and rough fault interfaces. Second, we scale the rise time of the source time function so that the modeled waveforms represent the correct radiated seismic energy. The method is validated for the 2008 Wenchuan, China, earthquake and the 2003 Tokachi-Oki, Japan, earthquake. We demonstrate the robustness of our approach with regard to changes of the assumed rupture velocity. We find the fine source discretizations combined with the small scale source variability ensure that the high frequencies (1–8 Hz) are satisfactorily introduced, justifying the deterministic wave propagation approach even at high frequencies. The adjustment of the rise time via the radiated seismic energy permits a simulation without making assumptions on the stress drop, as is usually done by other modeling approaches. By varying different parameters, such as the energy magnitude, the simulation approach could be especially useful for estimating the range of possible ground motions issuing from a distinct fault in a future earthquake. The rise-time scaling may also be used for seismogram modeling in the context of early-response systems as the energy magnitude, which is the parameter needed for the scaling, is available shortly after the earthquake. Online Material: Tables of kinematic rupture models for 2008 Wenchuan and 2003 Tokachi-Oki, and Fourier spectra of simulations.