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 × 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.

The surface-waves methods are well-established techniques for subsurface S-wave velocity (VS) reconstruction. Recently, the sensitivity of surface-wave skin depth to Poisson ratio was applied to also estimate P-wave velocity (VP) models from surface-wave records. We use this technique within the framework of three surface-wave methods, the wavelength/depth data transform, the laterally constrained inversion, and surface-wave tomography to estimate both VS and VP models. We apply these methods to a 3-D test data set from a mining site that is characterized by stiff material and by significant elevation contrast. The data were recorded using a regular grid of receivers and an irregular source layout. Pseudo 3D VS and VP models were obtained down to 140 m depth over approximately 900 × 1500 m2 area. The estimated models from the methods well-match the geological information available for the site. Less than 6 % difference is observed between the estimated VS models from the three methods, whereas this value is 7.1 % for the retrieved VP models. The different methods are critically compared in terms of resolution and efficiency.