3-D shear velocity inversion based on group velocity dispersion with low spatial sampling surface wave data

The shear wave velocity can be estimated by inverting the phase or group velocity dispersion curves of surface wave. Phase velocity dispersion imaging methods are often significantly affected by spatial aliasing. In contrast, group velocity estimation primarily relies on time-frequency analysis methods without wavenumber computation. This study introduces a method for 3-D near surface shear wave velocity modeling based on group velocity dispersion curves and demonstrates its applicability at the petroleum exploration scale. First, a synthetic example is used to conduct an analysis of the influence of spatial aliasing on dispersion imaging. By comparing the sensitivity of phase and group velocity dispersion curves to shear wave velocity variations, we further evaluate their respective inversion performances. Subsequently, the robustness of the group-velocity-based approach is validated through a synthetic test with added noise. Finally, a field data example of petroleum exploration is presented. The results demonstrate that the proposed method can reconstruct high resolution 3-D shear wave velocity models, which show strong correlation with compressional wave velocity models derived from first arrival tomography. The findings indicate that, compared with conventional phase velocity dispersion curve inversion, the proposed method demonstrates superior robustness and resolution when processing data with limited spatial sampling.