Shear-Wave Velocity Reconstruction via Unconventional Joint Analysis of Surface Waves: A Case Study in the Light of Some Theoretical Aspects

In site characterisation studies, the unambiguous determination of the shear-wave velocity (VS) vertical profile is a crucial point often accomplished via surface-wave analysis. The determination of the dispersive properties eventually inverted for the determination of the VS vertical profile, can be performed both via active and passive methodologies and, for land data, while considering both Rayleigh and/or Love waves. Because of its constitutive equations, Rayleigh-wave propagation is often characterized by a complex phenomenology determining non-trivial mode excitement (thus complex velocity spectra), while Love waves typically result so-to-speak simpler. These aspects logically suggest the use of a joint approach capable of reducing the non-uniqueness of the solution and solving possible interpretative issues particularly problematic when the inversion is performed according to the classical approach (picking of interpreted dispersion curves and successive inversion). After the presentation of a synthetic dataset shown to put in evidence the above-mentioned problematic aspects, a case study solved while adopting a non-ordinary approach (the joint inversion of the whole Rayleigh-and Love-wave velocity spectra accomplished by considering the Full Velocity Spectrum approach) is presented.