Publication Date:
2016-07-24
Description:
Multiparameter full waveform inversion (FWI) applied to an elastic orthorhombic model description of the subsurface requires in theory a nine-parameter representation of each pixel of the model. Even with optimal acquisition on the Earth surface that includes large offsets, full azimuth, and multicomponent sensors, the potential for trade-off between the elastic orthorhombic parameters are large. The first step to understanding such trade-off is analysing the scattering potential of each parameter, and specifically, its scattering radiation patterns. We investigate such radiation patterns for diffraction and for scattering from a horizontal reflector considering a background isotropic model. The radiation patterns show considerable potential for trade-off between the parameters and the potentially limited resolution in their recovery. The radiation patterns of C 11 , C 22 , and C 33 are well separated so that we expect to recover these parameters with limited trade-offs. However, the resolution of their recovery represented by recovered range of model wavenumbers varies between these parameters. We can only invert for the short wavelength components (reflection) of C 33 while we can mainly invert for the long wavelength components (transmission) of the elastic coefficients C 11 and C 22 if we have large enough offsets. The elastic coefficients C 13 , C 23 , and C 12 suffer from strong trade-offs with C 55 , C 44 , and C 66 , respectively. The trade-offs between C 13 and C 55 , as well as C 23 and C 44 , can be partially mitigated if we acquire P – SV and SV – SV waves. However, to reduce the trade-offs between C 12 and C 66 , we require credible SH – SH waves. The analytical radiation patterns of the elastic constants are supported by numerical gradients of these parameters.
Keywords:
Marine Geosciences and Applied Geophysics
Print ISSN:
0956-540X
Electronic ISSN:
1365-246X
Topics:
Geosciences
Published by
Oxford University Press
on behalf of
The Deutsche Geophysikalische Gesellschaft (DGG) and the Royal Astronomical Society (RAS).
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