One-dimensional multi-spectral analyses of surface waves (MASW) are used to predict subsurface shear-wave interval velocities. Shear wave velocities can also extract additional velocity-related information such as mechanical properties of soils and rocks. In general, MASW data compare favorably to other geophysical methods for predicting interval velocities. Furthermore, comparisons to vertical seismic profiles correlate well with MASW predicted shearwave interval velocities.
Over 100 one-dimensional MASW records and 30 vertical seismic profiles in 5 states were collected and compared. Surface waves saturate the geophones (5-foot spread with 5-foot hammer offset) on bedrock and dispersion curves are difficult to evaluate. Consequently, MASW-derived shear-wave velocities are elevated above those derived from down-hole vertical seismic profile methods (VSP). MASW-derived shear-wave velocities collected in areas with a veneer to thick sequences of unconsolidated soil have predicted MASW shear-wave interval velocities that compare favorably to those derived from VSP data.
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