HR: 14:30h
AN: S33A-05    [Abstracts]
TI: Nonlinear Velocity Inversion via Extension - Layered Case
AU: * Symes, W W
EM: symes@caam.rice.edu
AF: Rice University, 6100 Main St., Houston, TX 77005 United States
AB: Migration velocity analysis, like all other aspects of migration,, is based on the Born or single-scattering approximation. It is capable of correcting large errors in a velocity model of the Earth, but cannot account directly for multiply reflected energy and other nonlinear effects. Inversion via data fitting, on the other hand, may be based on full waveform (nonlinear) modeling. Given a good enough starting estimate of seismic wave velocity, full waveform inversion can account for both single and multiple scattering. Considerable experience suggests, however, that (iterative) inversion of this type is unlikely to succeed unless provided with a relatively accurate initial model of velocity. The extended model concept provides a common framework for migration velocity analysis and nonlinear inversion, and suggests an approach to nonlinear velocity analysis integrating singly and multiply scattered energy. The extended model replaces the wave velocity with an operator. Its kernel corresponds to the image volume of prestack migration. In fact this image volume may be identified with the perturbation of the operator kernal about an ordinary acoustic or elastic model. The layered medium case is particularly simple and amenable to computational experimentation: the operator extension of the velocity is necessarily a convolution operator in the horizontal variables, and admits diagonalization via the discrete cosine transform. This talk will briefly sketch the framework of extended inversion and present some first numerical results in the layered case.
DE: 3210 Modeling
DE: 3230 Numerical solutions
DE: 3260 Inverse theory
DE: 7203 Body wave propagation
DE: 7260 Theory and modeling
SC: Seismology [S]
MN: 2005 Joint Assembly