After correction by the group velocity and the phase shift, the slow Pseudo-Rayleigh wave is flattened and rendered non-dispersed. The group velocity correction is 189 m/s. The phase correction is 22 degrees. The non-dispersive Pseudo-Rayleigh wave is extracted by using SVD filter. Once estimated, the dispersion properties of the slow Pseudo-Rayleigh wave are recovered by applying opposite corrections in velocity and phase.

The example shows several sections and their 2D spectrum. It is possible to see either:

• The initial noise shot;
• The estimation of the slow wave by SVD filter after recovery of dispersion properties. This section is the sum of N singular sections. Number N can be chosen between 1 and 5;
• The residual section.

Several singular sections are necessary to obtain a good estimation of the slow Pseudo Rayleigh wave.