Unconventional optimized surface wave acquisition and analysis: Comparative tests in a perilagoon area

Abstract

In order to investigate the sedimentary cover of a vast perilagoon area from the geotechnical point of view and test different possible and unconventional approaches to surface-wave analysis, a series of different acquisitions and analysis procedures are tested, always considering the need for a light equipment and simple field procedures.In one case a joint inversion of the Horizontal-to-Vertical Spectral Ratio (HVSR — passive seismics) and Rayleigh-wave group-velocity spectrum (active seismics) is performed and results eventually compared to simpler single-component inversion of the group-velocity spectrum only (in both cases the group-velocity spectrum is considered according to the Full Velocity Spectrum – FVS – approach).For a second site, active data collected by using a single 3-component geophone are holistically inverted by considering the group-velocity spectra of the radial- and vertical-components of Rayleigh waves, jointly with the Radial-to-Vertical Spectral Ratio (RVSR). A second procedure based on purely-passive data (HVSR curve and phase velocity dispersion curve determined via Miniature Array Analysis of Microtremors) was also considered and results compared.In all cases, results appear extremely consistent providing mutual evidence of the efficiency of the considered methods and showing very homogenous stratigraphic conditions in the investigated area.