Belahi, Thomas, Visco-elastic FWI

Belahi, Thomas

Visco-elastic full waveform inversion for velocity model building and imaging

N. Fuji, S. Singh (IPGP)

Viscoelasticity broadens waveforms and changes their amplitudes. It is a very crucial parameter to understand energy dissipating media such as porous media, salt body or small liquid sites in the Earth’s subsurface. However, viscoelastic effects are secondary compared to elastic effects, characterized by P-wave and S-wave velocity or even anisotropy. The aim of this thesis is to develop a methodology for inverting seismic waveforms for elastic and viscoelastic inner structure. Our methodology allows us to invert waveforms in time domain for elasticity and anelasticity simultaneously and hence it obtains effectively and efficiently elastic and anelastic models. Synthetics are calculated with finite difference methods. In order to obtain a good initial model, we will perform wave equation tomogra- phy (finite frequency tomography) for both elasticity and anelasticity using traveltimes and t* measured by cross correlation, respectively.