Land seismic multi-parameter full waveform inversion in elastic VTI media by simultaneously interpreting body waves and surface waves with optimal transport based objective function | INSTITUT DE PHYSIQUE DU GLOBE DE PARIS

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  Land seismic multi-parameter full waveform inversion in elastic VTI media by simultaneously interpreting body waves and surface waves with optimal transport based objective function

Mercredi 06 Mars 2019
Séminaire de sismologie, de géosciences marines et de géophysique d'exploration
Weiguang He
(Université Grenoble Alpes)
Extrait: 

Land seismic multi-parameter full waveform inversion in anisotropic media is challenging
because of high medium contrasts and because of surface waves. With a data-residual leastsquares
misfit function, the surface wave energy usually masks the body waves and the gradient
of the misfit function exhibits high values in the very shallow depths preventing from recovering
the deeper part of the earth model parameters. The optimal transport objective function,
coupled with a Gaussian time-windowing strategy, allows to overcome this issue by more focusing
on phase shifts and by balancing the contributions of the different events in the adjoint source
and the gradients. We first illustrate the advantages of the optimal transport function
with respect to the least-squares one, with two realistic examples. We then discuss a vertical
transverse isotropic (VTI) example starting from a quasi 1D isotropic initial model. Despite
some cycle-skipping issues in the initial model, the inversion based on the windowed optimal
transport approach converges. Both the near-surface complexities and the variations at depth
are recovered.