Fig. 1:

Flow chart of the proposed LPVI approach for double-sided push. Principal steps of the LPVI can be summarized as follows: (I) acquire a 3D shear wave velocity data set; (II) apply directional and band-pass filters to the data in a wavenumber domain; (III) transform the spatio-temporal data into a frequency domain; (IV) choose the spatial spectrum at a particular frequency f₀; (V) select a short space domains data; (VI) execute 1-D Fourier transforms in X and Z directions on the windowed wavefield regions; (VII) calculate spatial distribution of the phase velocity of the shear wave motion for the specified frequency and select ROI. Repeat previous steps for shear wave velocity data for the second push. Average resulting LPVI data for ROI’s from two pushes.