Multichannel Analysis Of Surface Waves (MASW) For Investigation Of Ground Competence: An Introduction

The Multichannel Analysis of Surface Waves (MASW) is a seismic method to investigate the competence of the ground, one of the essential geotechnical interests. It can provide dense coverage of data of ground competence quickly and economically in various stages of development projects.

This method, developed in the 1990s and first commercialized in 1999, analyses propagation of the seismic surface wave in the frequency domain and estimates the underground shear wave (S-wave) velocity structure. The S-wave velocity is an elastic parameter closely related to Young’s modulus, an important property to derive load bearing capacity of the ground.

Geometry for data collection for the MASW analysis is similar to the seismic refraction survey but simpler. It does not require a range of long offsets or a large geophone array for equivalent depth of investigation. As the MASW processing involves data transformation into the frequency-velocity domain, it is relatively CPU intensive. This is the reason why the method could not be put into practice until the 1990s, while the theory and possible use was speculated since 1950s. Through this processing, a dispersion curve of the seismic wave propagation is analysed and then inverted to the S-wave velocity structure.

This paper presents an introduction to the MASW method outlining its concept and application in a variety of geotechnical settings.