INVERSION FOR SHEAR WAVE VELOCITY IN SEDIMENTS AND ESTIMATION OF NEAR-SURFACE ANELASTIC PARAMETERS

Abstract

Standard seismic refraction data recorded in North-East Italy, were used to define the shear wave velocities in sediments by means of the inversion of the Rayleigh wave dispersion relation. The group velocity for the fundamental mode and the phase velocity for the fundamental and first few higber modes were measured in the frequency range 'from 12 to 28 Hz. The inversion of these data gave a well defined S-wave velocity structure of the weathered zone to a depth of 38 meters. Using this information in the computation of complete synthetic seismograms for anelastic media, allowed a qualitative estimation, in the same depth range, of the distribution with depth of the quality factor, Q.