2D full waveform inversion (FWI) of shallow seismic Rayleigh waves has become a powerful method for reconstructing viscoelastic multiparameter models of shallow subsurface with high resolution. The multiparameter reconstruction in FWI is challenging due to the potential presence of crosstalk between different parameters and the unbalanced sensitivity of Rayleigh-wave data with respect to different parameter classes. Accounting for the inverse Hessian using truncated Newton methods based on second-order adjoint methods provides as an effective tool to mitigate crosstalk caused by the coupling between different parameters.
In this study, we apply a preconditioned truncated Newton method (PTN) to shallow-seismic FWI to simultaneously invert for multiparameters near-surface models (P- and S-wave velocities, attenuation of P and S waves, and density). We firstly investigate scattered wavefields caused by these parameters to evaluate the coupling between them. Then we investigate the performance of PTN on shallow-seismic FWI of Rayleigh wave for reconstructing all five parameters simultaneously. The application to spatially correlated and uncorrelated models demonstrate that PTN helps to mitigate the crosstalk and improves the resolution of the multiparameter reconstructions, especially for the weak parameters with small sensitivity such as attenuation and density parameters. ... mehrThe comparison with the classical preconditioned conjugate gradient method highlights the improved performance of PTN and thus the benefit of accounting for the information included in the Hessian.