Eigen Diagonal FAST Shear waveform G₂₂ (red) clearly exhibits nearly TWICE higher amplitudes than the SLOW Shear waveform G₁₁ (solid blue line, copied as dashed lines on G₂₂₎. Interestingly, the eigen waveforms G₂₂ and G₂₂ look very much alike on the first two peaks, after which they shape DIFFER, a major third peak present only on G₂₂, in spite of the SIMILAR shape of the source pulses emitted by the two orthogonal transmitters mounted on the DSI dipole sonic tool. The energy of the two source transmitters has been equalized after filtering out the DC offset at preprocessing stage, before 4C inversion and diagonalisation of the recorded flexural wave signals.