Subsurface Characterization using MASW: Preliminary Experimentation and analysis

Abstract — This paper describes the application of Multichannel analysis of surface waves (MASW) to characterize the subsurface. Active MASW survey has been conducted in the plain terrain near the Civil Engineering Department, IIT Guwahati. The output signals collected in the geophones during the experimentation (time-domain signals) is post-processed through Fast Fourier Transform (FFT) with the aid of a developed Matlab code to obtain the frequency-domain signals. Following the existing phase-shift method, summed-up normalized amplitude with varying phase velocity curve is determined which is very important for the identification of energy accumulation in the dispersion image space. A commercially available software known as EasyMASW is introduced to obtain the shear wave velocity profile of the soil. EasyMASW results shows that the shear wave velocity is affected by the sampling frequency of data acquisition. The ambiguity in the results obtained from EasyMASW is also highlighted. Keywords—dispersion analysis, phase-shift, multichannel analysis of surface waves, frequency-domain. I