Comparison of different surface wave inversion methods in engineering scale

Luping Qu, Kristopher A. H. Innanen

Multichannel Analysis of Surface Wave (MASW) inverts the S wave velocity using the Rayleigh dispersion curve. It has three steps: field data acquisition, dispersion analysis, inversion analysis. Due to its robustness and simplicity, it is the most widely used method to characterize the near surface velocity. Factors influencing the method’s accuracy are analyzed, and the determination method for the initial input parameters is given. Advantages and limitations of MASW are introduced in this paper. For modeling tests, we used SPECFEM to generate synthetic data, using the misfit of the generated dispersion curve and picked dispersion curve of the synthetic data to update S wave velocity. The least square Gauss-Newton inversion method is adopted to minimize the misfit. The damping parameter and stability parameter of the inversion are tested. In addition, global optimization methods like Simulated Annealing and Monte Carlo using Markov Chain were applied to simple layered models.