A Novel Approach to Model Surface Wave Propagation in Layered Media

The fidelity of the surface wave inversion is greatly influenced by the efficiency and accuracy of the forward analysis. Existing forward modelling approaches generate only theoretically calculated dispersion curves without any information regarding the modal amplitude. The present study proposes a semi-analytical forward modelling approach to determine the dispersion image from a 1D profile similar to that produced by multichannel field data. An analytical solution is used in the horizontal direction, and finite element discretization is applied in the vertical direction. The infinitely extended elastic half-space is efficiently modelled by using perfectly matched discrete layer (PMDL) elements. The higher-order finite element discretization and the use of PMDL elements significantly reduce the computational cost. The proposed method calculates the vertical displacement responses at different receiver positions on the surface in frequency-space domain. The complex frequency-space domain response is transformed into seismogram data and velocity spectra.