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At 12:52 (local time, UTC + 08:00) on September 5, 2022, an earthquake of magnitude 6.6 occurred in Luding of the Sichuan Province (southwest China). Combined with the empirical relationship between magnitude and global–local source parameters, the hybrid source model of the Luding earthquake was applied. In a simulation, the source model was mainly described by global source parameters and local source parameters. Based on the empirical relationship between global source parameters and magnitude, we obtained the mean values of global source parameters. In combination with the standard deviation given by the empirical formula, the source parameters satisfying the mean value and standard deviation were generated based on the modified truncated normal distribution function. The observation points were selected considering the various geological conditions and orientations, and then, they were generated based on the acceleration waveforms of the selected observation points using the finite-fault approach through the dynamic corner frequency. Next, their values were used to calculate the acceleration response spectra of these target points. Then, the source model corresponding to the 5% damped pseudospectral acceleration (PSA) with the minimum residual of the average response spectra was selected and is finally set as the optimal source model for the Luding earthquake in China. Finally, the slip distributions of two models were compared, the response spectra were obtained, and the impacts of the two source models on the simulation results were investigated. The results verified the reliability of the source model estimated in this study and showed that the influence of the source model on the simulation results is mainly present in the short period. In addition, the results indicate that the method obtained in this study can be used to quickly predict the source model for earthquake scenarios. [ABSTRACT FROM AUTHOR]

On September 5, 2022 (local time), a magnitude 6.6 earthquake was reported to have occurred in Luding County, Sichuan Province, Southwest China. In this simulation, a widely used stochastic finite-fault model was used to analyze how the source models affect the near-fault earthquake ground motion simulations of the 2022 Mw 6.6 Luding earthquake in China. Seven different slip models, one of them obtained from common fault parameters and random distributed slip amount, were used to yield the best match with the recordings. The simulated earthquake ground motions calculated in the frequency band of 0.05–20 Hz were compared with the observed values in both the time and frequency domains. Twelve acceleration observation stations located near the fault plane were selected in our simulation for comparison. The average H/V curves were estimated using the available acceleration records to consider the local site effect at each selected station. The research results indicate that none of the source models adopted in this study fully estimate the observed values at all the selected ground-motion stations. The simulated values of some slip models underestimate the level of the Fourier amplitude spectrum at frequencies above 6 Hz. The underestimation may be attributed to the directivity effect, which may produce a higher amplitude of observed ground motion in the high-frequency band. All the slip models show similar average model deviations except for the random slip model. Finally, the peak ground accelerations and peak ground velocities were predicted at these selected near-fault observation stations. The results indicate that the peak accelerations and velocities obtained from seven slip models correlate well with each other, but are slightly lower than the recorded values at most stations. In addition, the synthetized results calculated from the random and inverted slip models can be the same level only if a greater stress drop is adopted in the random model. [ABSTRACT FROM AUTHOR]