Study Of Source Rupture Process Of Jiuzhaigou Earthquake Based On Inversion Of Teleseismic Waveforms

The study of the source rupture process is of great significance for understanding the characteristics of seismic disaster and source rupture.Efficient inversion for earthquake rupture history based on the far-field P-wave data can help quickly obtain the spatial-temporal feature of rupture process after the event and service for post-earthquake disaster relief and earthquake rescue.Besides,as the ground motion is significantly affected by the source in the near field region,rapid and reasonable expression of the source rupture process is also significant to near-field ground motion simulation and helpful to seismic analysis of engineering structures.In this paper,taking the 2017 Jiuzhaigou earthquake as the target,the source rupture process was quickly inversed using far-field P-wave data.At the same time,the engineering forecasting source model was established for the Jiuzhaigou earthquake.By the means of Stochastic Ground Motion Synthesis Method Based on Finite Fault Model,near-field ground motion simulation results of prediction source model and inversion source model were computed and compared.The main contents of this paper are as follows:Firstly,the process of raw seismic records and the method of finite-fault inversion,as well as the Stochastic Ground Motion Synthesis Method Based on Finite Fault Model.Taking the 2017 Jiuzhaigou earthquake as the target,22 sets of far-field P-wave data were selected and the synthetic records of pre-defined fault were calculated with the help of the generalized rays theory.By fitting the observations and adding two constrains: spatial smoothing and moment-minimization,source slide model and source time function were determined.The hybrid slide model was established for the Jiuzhaigou earthquake and seismic source parameters are determined by semi-empirical calibration law.Furthermore,30 sets of different value combinations of seismic source parameters are generated by truncation normal distribution to express the discreteness of seismic source parameters,thereby,30 sets of finite fault source models are formed and representative seismic source model was selected from these models.By using the method of Stochastic Ground Motion Synthesis Based on finite-fault model,the earthquake motion field of Jiuzhaigou scenario earthquake,based on representative source model and slip distribution from inversion,were calculated respectively,and corresponding pseudo-acceleration response spectrum curves and PGA distributions were drawn,showing similar results from two types of models,indicating that the finite fault source model estimated by the hybrid slide model and the source model from teleseismic P wave inversion are both equal effective in ground motion estimation.