New processing flow for surface wave dispersion curve inversion of near surface 2-D Vs model

Abstract

Summary In this paper, a processing flow for estimating the near surface 2-D Vs velocity model using Rayleigh surface wave dispersion curve is established. Rayleigh surface wave dispersion energy diagram is extracted by frequency decomposition method. However, due to the low resolution of the extracted dispersive energy map, the window superposition method is introduced to superimpose the dispersive energy of multiple shot points in the same window on the dispersive energy map in the center of the common window. Then move the window along the direction of the acquisition line to extract the dispersive energy map at different positions. 2-D search is carried out on the periodic grid of phase velocity, and the dispersion points are selected from the superimposed energy peaks. Windowing and stacking can also smooth the lateral changes of the model and improve the signal-to-noise ratio. Then, the singular value decomposition based damped least square method is used to inverse the one-dimensional Vs velocity, and the inverse 1-D Vs velocity is interpolated to obtain the 2-D Vs velocity profile. The simulation data and the actual data of Yellowstone National Park shared by Sylvain pasquet and Ludovic bodet (2017) show the effectiveness of the processing process.