Multichannel Analysis of Surface Waves (MASW) is a fast and practical method of obtaining subsurface information without disturbing a site. Geophones are placed on the ground at regular intervals, and used to measure surface waves which travel along the ground. This provides measurements of Shear Wave Velocity to depths of 50m or so, providing Shear Modulus and small-strain stiffness to these depths. Unlike refraction testing, the MASW test can detect weaker layers beneath stronger layers.

MASW performed with a landstreamer

The system can be towed behind a vehicle providing very rapid data acquisition - over 750 linear metres can be surveyed in one day. The system can provide:

• Depth to rock

• Rippability

• Measurement of Small Strain Shear Modulus (G)

• Derivation of Youngs Modulus (E)

• Definition of weak compressible soils

• Compaction certification (especially useful if done before and after compaction to measure relative improvement)

• When used with CPTs or other invasive testing, MASW provides excellent information in between these tests to obtain a much greater test coverage of the site