Horizontal-to-vertical spectral ratio inversion using Monte Carlo approach and enhanced by Rayleigh wave dispersion curve

The inversion of Rayleigh dispersion curve has been used to estimate the Vs ground profiles (thickness of soil layers vs. shear wave velocity, Vs) of a site. These Rayleigh dispersion curves are usually retrieved using several geophones or sensors set up in linear array for active methods (e.g., Multichannel Analysis of SurfaceWaves-MASW), or linear array (Refraction Microtremor-ReMi) and/or geometrical array for passive methods. In recent years, the inversion of Horizontal-to-Vertical Spectral Ratio (HVSR) of passive microtremor records has become popular because only one station consisting of a 3 component sensor (one vertical and two horizontal components) is needed to carry out the field measurements.According to the results reported by several researchers, a more detailed estimation of shallow layers might be obtained when the HVSR inversion is applied. However, supplementary field surveys, such as Cone PenetrationTest (CPT), are needed to obtain reliable HVSR inversions, meaning that the characterisation of surface layers without supplementary geotechnical surveys are estimated with some uncertainties and should be avoided. In this paper, an attempt to estimate reliable overall Vs ground models is carried out from the HVSR inversion using the Monte Carlo approach and enhanced by the Rayleigh wave dispersion curve. As case study, a dynamically compacted area of the Penrith Lakes site is assessed by the proposed technique. From the results obtained at this site, a detailed Vs ground model resembling CPT record was obtained.