Some Practical Aspects of Masw Analysis and Processing

We use multi-channel analysis of surface waves (MASW) on seismic data in an attempt to test data acquisition parameters and compare those results to reaffirm existing general theoretical recommendations and rules of thumb. Of particular interest were optimum seismic receiver spread size, minimum and maximum receiver offsets and dominant geophone frequency for best-case fundamentalmode dispersion-curve evaluation of the Rayleigh wave. Recommended MASW parameter selection criteria are tested on seismic data collected at various sites, such as desert setting, river sediments, and glacier, for which shear-wave properties were estimated. Presented MASW results demonstrate that observing optimal parameter selection can improve the resolution and quality of the fundamental-mode dispersion-curve images of the surface wave and the final 2D Vs section. After comparing the optimal parameter selection approach with the general theoretical recommendations it was concluded that the rules of thumb are s a good starting point, especially when applying the MASW method at a site with unknown seismic characteristics. However, optimal acquisition and processing MASW parameter selection can be best achieved using field site tests and is the preferred approach over theoretical recommendations. Specifically testing a selected brand of geophones, it is expected that, in general, frequencies as low as one octave and a half bellow the natural geophone frequency can be recommended used for most MASW analysis.