Comparison of surface-wave techniques to estimate S- and P-wave velocity models from active seismic data

The acquisition of seismic exploration data in remote locations presents several logistical and economic criticalities. The irregular distribution of sources and/or receivers facilitates seismic acquisition operations in these areas. A convenient approach is to deploy nodal receivers on a regular grid and to use sources only in accessible locations, creating an irregular source-receiver layout. It is essential to evaluate, adapt, and verify processing workflows, specifically for near-surface velocity model estimation using surface-wave analysis, when working with these types of datasets. In this study, we applied three surface-wave techniques (i.e., wavelength-depth (W/D) method, laterally constrained inversion (LCI), and surface-wave tomography (SWT)) to a large-scale 3D dataset obtained from a hard-rock site using the irregular source-receiver acquisition method. The methods were fine-tuned for the data obtained from hard-rock sites, which typically exhibit a low signal-to-noise ratio. The wavelength-depth method is a data transformation method that is based on a relationship between skin depth and surface-wave wavelength and provides both S- and P-wave velocity ( V s and V p ) models. We used Poisson's ratios estimated through the wavelength-depth method to constrain the laterally constrained inversion and surface-wave tomography and to retrieve both V s and V p also from these methods. The pseudo-3D V s and V p models were obtained down to 140 m depth over an area of approximately 900 x 1500 m 2 . The estimated models from the methods matched the geological information available for the site. A difference of less than 6 % was observed between the estimated V s models from the three methods, whereas this value was 7.1 % for the retrieved V p models. The methods were critically compared in terms of resolution and efficiency, which provides valuable insights into the potential of surface-wave analysis for estimating near-surface models at hard-rock sites.