Stochastic finite-fault modelling of Ms 6.8 Luding earthquake in 2022 and seismic hazard scenario of Moxi Fault, Southwest China

Abstract

Abstract The establishment of ground motion model is a crucial component of seismic hazard analysis, and the numerical simulation technology of ground motion is widely used in regions with insufficient earthquake records. Based on the stochastic finite-fault method, the present work performed the scenario-based seismic hazard analysis of Moxi fault. Considering the variety of site amplification caused by complex terrain, genetic algorithm was conducted to identify the site amplification. Through the simulation of the Ms 6.8 Luding earthquake in 2022, it was found that the correction of site amplification effectively reduced the model deviation, and made the simulated 5%-damped spectral acceleration (SA) in good agreement with the observation. After that, the ground motion of the Mw 7.1 scenario earthquake was synthesized using the calibrated input parameters and hybrid source model, so as to effectively reflect the uncertainty of source parameters. The scenario earthquake was discussed through: 1) sensitivity analysis of stress drop and upper-edge buried depth; 2) identification of the probability distribution of SA at 0.8 s, which represented the dynamic characteristics of engineering structures; 3) generation of seismic hazard map using ground motion intensity index. The prediction of the scenario earthquake provided a basis for earthquake disaster loss evaluation and seismic fortification of engineering structures.