We generate a surface wave by using a land seismic source. The seismic waves (Rayleigh waves) are recorded by using a multi-channel streamer and a seismic recorder (one or more).
Our QC software of processing data on line calculates the curves of dispersion for each shot. These curves describe the properties of propagation of the surface wave. They are used to compute the shear wave velocity until 50 m of depth. As shear wave velocity is directly proportional to the modulus of rigidity, this gives us an immediate indication on the profile of the stiffness or rigidity of the grounds without having to carry out drilling, cross-hole or another expensive technique. This technique is non invasive.
Acquisition set-up for a land survey
The traditional seismic methods used to measure compression and shear wave velocities are the cross-hole and down-hole which requires the use of drillings, expensive and long.
Correlation between the shear wave velocity
obtained with the surface wave (Vs SP 46 and 40) and cross-hole