Slip-Correlated High-Frequency Scaling Factor for Stochastic Finite-Fault Modeling of Ground Motion

Abstract

ABSTRACTTo eliminate the effect of the subfault dimension on the synthetic ground motion of the stochastic finite-fault technique, Motazedian and Atkinson developed the dynamic corner frequency. Furthermore, they derived a high-frequency scaling factor based on the velocity spectrum to compensate for the underestimation of the ground-motion source spectrum amplitude in the high-frequency range caused by the dynamic corner frequency. However, this high-frequency scaling factor was developed on the assumption that the slip amount, seismic moment, and the high-frequency received energy of each subfault on the rupture surface were the same. Considering the nonuniformity of the slip of each subfault and the large amount of received energy released on the asperity body, the received energy of the entire fault was distributed to each subfault according to the ratio of the slip of the subfault to the total slip. This could ensure not only that the high-frequency received energy radiated by the subfault with a large slip was greater but also that the total received energy was conserved. Finally, an example was used to discuss the effect of the improvement on the synthetic ground motion. The results showed that the proposed improved approach can further eliminate the dependence of the synthetic results on the dimension of the subfault.