Optimizing the Geotechnical Exploration of Vast Areas via Joint Multi-Component Surface-Wave Velocity Spectra Analysis

Surface wave analysis is nowadays routinely adopted for the exploration of large areas from the geotechnical point of view. This is usually accomplished by inverting the modal dispersion curves of successive shot gathers, therefore depicting the 2D subsurface structures in terms of shear-wave velocities. Such a classical approach (typically performed while uniquely considering the vertical component of Rayleigh waves) can result heavy (hundreds or thousands of velocity spectra to interpret and pick) and, in case of complex phase-velocity spectra, analyses can result inaccurate and biased by personal and potentially erroneous interpretations.

In the present work are presented some preliminary results of the implementation of a system (acquisition and processing procedures) aimed at determining 2D Vs sections following an unconventional approach. Data are acquired possibly according to a multi-component procedure, initially analyzed in relative terms to quickly put in evidence possible lateral variations and eventually (jointly) inverted to retrieve a robust 2D subsurface Vs structure.

Multi-component data acquisition is performed by considering the vertical component of Rayleigh waves and Love waves, while their joint inversion is performed according to the Full Velocity Spectra (FVS) approach, taking advantage of a highly-automated (though computationally intensive) process capable of better handling complex velocity spectra.