Acta Geodynamica et Geomaterialia

Title: SINGLE- AND MULTI-COMPONENT INVERSION OF RAYLEIGH WAVES ACQUIRED BYA SINGLE 3-COMPONENT GEOPHONE: AN ILLUSTRATIVE CASE STUDY
Authors: DalMoro Giancarlo and Puzzilli Luca Maria
DOI: 10.13168/AGG.2017.0024
Journal: Acta Geodynamica et Geomaterialia, Vol. 14, No. 4 (188), Prague 2017
Full Text: PDF file (3.7 MB)
Keywords: Vs30; surface wave analysis; Rayleigh wave dispersion; joint inversion; seismic
Abstract: Rayleigh wave dispersion can occur according to complex mode excitation such that the interpretation of the phase or group velocity spectra can be erroneous thus leading to wrong reconstruction of the subsurface shear-wave velocity profile. In this paper, we present a case study solved by considering the holistic analysis of the Rayleigh waves recorded by a single three-component (3C) geophone and inverted by considering the group-velocity spectra of the radial and vertical components together with the Radial-to-Vertical Spectral Ratio (RVSR) and the RPM (Rayleigh-wave Particle Motion) frequency curve. In order to test the performance of the considered methodologies, we intentionally considered a complex site characterized by a high level of background noise and with a limited space to perform the investigation. In addition, passive data collected by the same 3C geophone are used to compute the Horizontal-to-Vertical Spectral Ratio (HVSR). Due to the vibrations produced by a nearby excavator, in order to obtain a meaningful HVSR we selected only a small portion of the recorded data. Computed HVSR is then jointly inverted with the active data to further validate the retrieved subsurface model and obtain information about the shear-wave velocities of the deeper layers. Altogether, four different inversion strategies are pursued and the obtained VS profiles compared also with the data available from local penetrometer test and borehole information.