A modified stochastic finite-fault method for estimating strong ground motion: Validation and application

Abstract

We developed a modified stochastic finite-fault method for estimating strong ground motions. An adjustment to the dynamic corner frequency was introduced, which accounted for the effect of the location of the subfault relative to the hypocenter and rupture propagation direction, to account for the influence of the rupture propagation direction on the subfault dynamic corner frequency. By comparing the peak ground acceleration (PGA), pseudo-absolute response spectra acceleration (PSA, damping ratio of 5%), and duration, the results of the modified and existing methods were compared, demonstrating that our proposed adjustment to the dynamic corner frequency can accurately reflect the rupture directivity effect. We applied our modified method to simulate near-field strong motions within 150 km of the 2008 MW7.9 Wenchuan earthquake rupture. Our modified method performed well over a broad period range, particularly at 0.04–4 s. The total deviations of the stochastic finite-fault method (EXSIM) and the modified EXSIM were 0.1676 and 0.1494, respectively. The modified method can effectively account for the influence of the rupture propagation direction and provide more realistic ground motion estimations for earthquake disaster mitigation.