Full-Waveform Inversion of Near-Surface Seismic Data in Anisotropic Media
V. Krampe, Y. Pan and T. Bohlen
Event name: 24th European Meeting of Environmental and Engineering Geophysics
Session: Modelling, Inversion and Data-processing in Near Surface Geophysics IV
Publication date: 09 September 2018
Info: Extended abstract, PDF ( 565.47Kb )
Price: € 20
In most shallow-seismic FWI studies, an isotropic assumption of the Earth is used, even if near-surface materials may exhibit strong seismic anisotropy. We investigate in this work the effects of anisotropy on surface waves and on shallow-seismic FWI. The comparison of seismograms calculated in isotropic and vertically transversely isotropic (VTI) models shows that Love waves have a higher sensitivity on anisotropy than Rayleigh waves, and are sensitive to both vertical and horizontal velocity. Therefore, we use Love waves for anisotropic FWI and invert for horizontal and vertical shear wave velocities simultaneously. We test the inversion on synthetic VTI data and compare the results of isotropic and anisotropic inversion. Ignoring anisotropy causes strong artifacts in the resulting models and neither horizontal nor vertical velocities are reconstructed. However, if we consider anisotropy and invert for horizontal and vertical velocity simultaneously, both velocity models can be reconstructed almost perfectly. We thus show the importance of considering anisotropy and the potential of anisotropic FWI in shallow-seismics, which improves the accuracy of the reconstructed subsurface models.