MASW first measures seismic surface waves generated from various types of seismic sources—such as sledge hammer—analyzes the propagation velocities of those surface waves, and then finally deduces shear-wave velocity (Vs) variations below the surveyed area that is most responsible for the analyzed propagation velocity pattern of surface waves. Shear-wave velocity (Vs) is one of the elastic constants and closely related to Young’s and shear moduli. Under most circumstances, Vs is a direct indicator of the ground strength (stiffness) and therefore commonly used to derive load-bearing capacity.
Overall procedure to produce a typical 2D S-velocity (Vs) cross section consists of collecting multichannel seismic records at multiple locations as illustrated below. Each record then generates a 1-D (depth) velocity (Vs) profile, multiple of which will construct the final 2D cross section.