Multichannel Surface Wave Analysis (MASW)
Seismic Surveying in Fair City
MASW uses analysis of seismic surface waves to calculate the shear wave velocity and to determine the small strain shear modulus below the land.
The survey is similar to seismic refraction data acquisition and these two methods are often carried out together using geophones, a hammer source and a seismograph.
Surveys are commonly done as 1D or 2D measurements, in the first case creating a shear wave versus depth graph and in the second case a 2D-cross section.
The main target of this method is the overburden and especially the characterisation of very soft to firm layers. The method can be also used to test the compaction of fill material at road or other construction sites.
The data processing uses the dispersion curves for the surface waves which is an easy computer process but the correct use of this requires an enormous amount of the geophysicists’ experience. Data is displayed as graphs, sections and often tabulated for the geotechnical engineer’s use in foundation design.