EFFECTS OF REDUCTIONS IN NUMBER OF CHANNELS ON RAYLEIGH AND LOVE WAVE DISPERSION IMAGES ACQUIRED USING THE MULTICHANNEL ANALYSIS OF SURFACE WAVES (MASW) METHOD

The Multichannel Analysis of Surface Wave (MASW) method is widely used in research and practice to characterize subsurface conditions. Typically in this method, Rayleigh or Love wave are first generated using active impacts, and collected by a series of receivers. Then, the waveforms are processed to generate dispersion images that represent velocities of different frequency components in the medium of interest. The depth of MASW investigation is directly proportional to the total spread length of receivers, and one factor that controls the resolution of the dispersion images is the total number of receivers used to acquire the surface waves. It is believed that for a fixed spread length, the larger number of receivers increases the resolution. While this statement has been investigated in the literature for Rayleigh waves, little attention has been placed on the effects number of receivers on Love wave dispersion images. This paper presents results from a MASW survey that proposes to address the effects of channel quantity on Rayleigh and Love wave dispersion images with a particular emphasis on Love waves. MASW records were collected with the same fixed spread length (34.5 m) and were processed considering various receiver quantities (24, 12, 8, and 6). Results indicate that Love waves dispersion images seem to be less sensitive to reductions in number of receivers. As an example, the Love wave dispersion image acquired by considering 8 channels can practically be considered equivalent to that acquired with 24 channels. This paper summarizes site conditions, hardware configurations and testing procedure, followed by a discussion of dispersion images and conclusions.