Theory

MULTICHANNEL ANALYSIS OF SURFACE WAVES (MASW) is a common seismic technique in Engineering Geophysics studies. MASW is a fast, low-cost, and environmentally friendly technique to estimate shear wave velocity profiles of geotechnical engineering sites. The surface wave technique is based upon the dispersion, or change in phase velocity with frequency (and therefore wavelength), of a seismic wave propagating through the subsurface. Longer wavelengths penetrate to deeper depths whilst shorter wavelengths are sensitive to the elastic properties of shallower layers. Surface wave dispersion is significant in the presence of velocity layering, which is common in the near-surface environment. The MASW method system operates by using an impulsive source and multiple receivers (multi-channel) along a much longer survey line. 
Applications

• Vs 30 calculated for Seismic Site Classification and Seismic Microzonation.
• Stratigraphic mapping and depth to bedrock
•  Anomaly detection (e.g. voids and tunnels)
•  Characterization of poorly consolidated or weak ground
•  Soil stiffness and ground improvement verification