Abstract

CORNOU, C et al. Shear-wave velocities in caracas inferred from inversion of phase velocities and ellipticities of rayleigh waves. Rev. Fac. Ing. UCV [online]. 2011, vol.26, n.2, pp.153-160. ISSN 0798-4065.

Reliable knowledge of soil mechanical properties, especially shear wave velocities, is important to estimate useful parameters in earthquake engineering (Vs30, response spectra, etc.) and to allow reliable numerical prediction of strong ground motion at frequencies of interest in earthquake engineering. Shear-wave velocity structure can be inferred either from borehole measurements (e.g. cross-hole or down-hole measurements) or from active or passive techniques using body- or surface-waves, respectively. Recent studies have also shown that ellipticity of Rayleigh waves can be extracted from microtremor measurements and subsequently jointly inverted with phase velocities in order to get reliable shear wave velocity profile down to seismic bedrock. In this paper, we present shear-wave profiles derived from joint inversion of phase velocity and ellipticity of Rayleigh waves obtained from microtremor array measurements at five different sites in Caracas. Phase velocities and ellipticities are extracted by using microtremor measurements. Derived shear-wave velocity profiles are consistent with available geotechnical and geophysical information.

Keywords : Microtremor arrays; Shear-wave profile; Ellipticity of Rayleigh waves; Joint inversion; Caracas.