Inversion Of Surface Waves In Complex Structures

Seismic techniques are nowadays widely used to image near-surface structures for both geomechanical and geological applications. However, in the context of shallow complex<br>structures, some limitations arise, particularly for inverting surface wave dispersion. In this paper, we introduce the full waveform inversion as an alternative to conventional MASW<br>(Multichannels Analysis of Surface Waves) methods typically used for subsurface prospecting. Considering 2D reference velocity models, we study the elastic wave propagation,<br>based on finite difference modelling in the frequency-space domain, for generating synthetic seismograms. The frequency versus phase-velocity curve, known as the dispersion curve, is afterwards computed and used to invert shear-wave velocities. Full-waveform inversion technique, based on the Born approximation, is tested using both body waves and surface waves to evaluate their respective contributions in the seismic imaging processes. The efficiency of such an inversion method compared to the classical MASW one is then evaluated.