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Presentation of the Master's Thesis: 2D elastic full-waveform inversion of Love waves in vertically transversely isotropic media

Presentation of the Master's Thesis: 2D elastic full-waveform inversion of Love waves in vertically transversely isotropic media
Datum:

23.10.2018

Referent:

Valérie Krampe

Abstract

In most shallow-seismic FWI studies, an isotropic approximation of the subsurface is used, even if most Earth materials are at least weakly anisotropic. We assume that for shallow sediments, a vertically transversely isotropic (VTI) approximation is more suitable due to the fine horizontal layering of the sediments. We investigate in this work the effects of this kind of anisotropy on surface waves and shallow-seismic FWI. The comparison of seismograms calculated in isotropic and VTI models shows that the sensitivity towards anisotropy is significantly higher for Love waves compared to Rayleigh waves. Therefore, we implemented the 2D anisotropic FWI only for SH waves. In synthetic examples, we investigate the capabilities of the VTI FWI. An almost perfect reconstruction of both horizontal and vertical velocities is possible, even if structures in the parameter models are spatially uncorrelated. To analyze the performance of VTI FWI also for a realistic case, we acquired field data at a site where the subsurface contains a highly anisotropic shale layer and applied the FWI to this data.