Hybrid broadband simulation of long-period ground motion in far-field basins based on group delay model

Abstract

Shallow seismic events often induce long-period ground motions in distant sedimentary basins, which can cause damage to structures. The current design earthquake input is usually based on amplitude, while the equally essential phase characteristics of far-field basin seismic waves are often ignored. To address this issue, this paper proposes a semi-empirical model based on group delay, which integrates the effects of source, path, local site, and basin on group delay, we characterize randomness of group delay through a parametric Gaussian probability framework, and approximates the frequency non-stationarity of positive and negative dispersion by introducing piecewise spline gradient regression. As an improvement of the stochastic finite fault method, the proposed method solves the problem that the original method cannot sufficiently reflect the phase characteristics and frequency non-stationarity of basin-induced seismic waves. Based on this model, the stochastic finite fault method and the spectral element method are combined to perform the hybrid simulation of basin ground motion, and the earthquake of 2003 Tokachi-Oki verifies the reliability of the proposed method.