Stochastic Simulation of Ground Motions of the Wenchuan Earthquake Using Slip-Based Corner Frequency and Scaling Factor

Abstract

Ground motions of the great Wenchuan earthquake were simulated using stochastic simulation technique with an improved source spectral model. In the model, the corner frequency for each subfault is determined based on a basic value calculated from the total seismic moment of the entire fault and an increment depending on the seismic moment assigned to the subfault. The model also includes a slip-based scaling factor accounts for the difference of the radiated energy from each subfault. The simulated ground motions were compared to those from using the source spectral model with dynamic corner frequency in terms of the mean spectral ratio over the 52 stations amd to the observation in terms of 5% damped response spectra. Based on the comparison, the effects of the slip-based corner frequency and the scaling factor on the simulation were discussed.

Synthesis of Strong Ground Motions at Two Rock Stations during the Great Wenchuan Earthquake from a Hybrid Source Model

“…where N L and N W are the numbers of sub sources along strike and dip directions respectively, a ij (t) is time history from the ij th sub source, ∆t 1 ij is time difference between the rupture in the sub source and the initial rupture, ∆t 2 ij is time difference between wave arrival times at the ground point from the sub source and from the rupture start point. Time history of motion from a sub source can be generated by Inverse Fourier Transform from amplitude spectrum and a random phase spectrum together.…”

“…A large number data recorded in Wenchuan earthquake 2008 promoted study on synthesis of near field ground motion. Many results were published in the past 5 years [1,2]. Most motion fields were synthesized by source models inversed mostly from far field observations [3][4][5].…”