Determination of Rayleigh wave dispersion curves for near surface applications in unconsolidated sediments

Abstract

Multi-channel Analysis of Surface Waves (MASW) is a suitable technique for vertical shear-wave velocity profile determination whose efficiency and effectiveness depends on data acquisition parameters and processing procedures. In the present paper we compare the performances of three different methods to determine Rayleigh waves dispersion curves. Such curves are successively exploited for the inversion process, which eventually provides subsurface information of use in geological or geotechnical applications. We investigate the role of some processing procedures, with a special emphasis on the number of traces able to optimise the ratio between information content and acquisition and processing costs. We show that phase shift method is able to produce the best results in terms of accuracy and computation efficiency for the unconsolidated sediments considered in our work. Phase shift shows extremely stable results also when a reduced number of traces is considered and other methods fail due to spatial aliasing or severe noise content that prevents from unambiguous interpretation.