Characterization of <i>in situ</i> rock density with SH- and Love-wave tomography: field data application

Abstract Acquiring detailed information on in situ rock density and its variability is essential for the design of shallow foundations. In this study, the 2D SH-Love full-waveform inversion (SH-Love FWI) method was used to determine rock density over large areas, eliminating the need for borings. The method takes advantage of the high sensitivity of SH- and Love-waves to material mass density, simultaneously inverts mass density and S-wave velocity (Vs), which can be used for shear modulus computation for foundation design. Validation through synthetic modeling demonstrated its capability to resolve complex subsurface profiles, including thin, high-density layers. Field experiments at two Florida sites confirmed the method's efficacy, accurately characterizing subsurface profiles of up to 18 m in depth with submeter resolution. At one site, the method identified two soil layers (density of 1400 kg/m³) and two rock layers (density of 1600 kg/m³). At another, it distinguished a soil layer (density of 1400 kg/m³), weathered and intact limestone layers (density of 1600 to 1800 kg/m³). Seismic-derived densities closely matched rock core results, confirming SH-Love FWI as a reliable tool for density estimation. Based on what we know, this is the first study to investigate and directly compare seismic-derived densities with those from rock coring samples.