HR: 0800h
AN: S31B-1061    [Abstracts]
TI: One-way Wavefield Extrapolation in Riemannian Coordinates
AU: Sava, P C
EM: paul@sep.stanford.edu
AF: Stanford University, Geophysics Department, Stanford, CA 94305 United States
AU: * Shragge, J C
EM: jeff@sep.stanford.edu
AF: Stanford University, Geophysics Department, Stanford, CA 94305 United States
AU: Fomel, S B
EM: sergey.fomel@beg.utexas.edu
AF: University of Texas at Austin, Jackson School of Geosciences, Bureau of Economic Geology, Austin, TX 78758 United States
AB: Images of crustal and lithospheric-scale structure can be created through seismic wavefield extrapolation, which extends surface-recorded data to depth through application of a wave-equation operator. The one-way extrapolation operators are derived from the acoustic wave-equation dispersion relation, and are usually defined in a Cartesian coordinate system with a vertical extrapolation axis. However, in this formulation there is an assumption that a vertical extrapolation axis can handle all wavefield propagation effects. In particular, there are numerous seismic imaging experiments where challenges such as incorporating rough topography, modeling overturning waves, and accounting for spherical Earth effects make extrapolation in Cartesian coordinates impractical. Riemannian wavefield extrapolation (RWE) (Sava and Fomel, 2004) is a generalization of the downward continuation concept to coordinate systems that incorporate geometrical or wave propagation effects. For example, geometrical effects such as topography can be directly incorporated into the coordinate system, and wavefield extrapolation commenced directly from relief (Shragge and Sava, AGU 2004). Another example is modeling path propagation effects directly in the coordinate system enabling accurate one-way wavefield extrapolation, even in situations where wavefields overturn. The method is implemented with a mixed domain solution involving both Fourier and space-domain finite differences. The algorithm is modestly more costly than wavefield extrapolation performed on a Cartesian computational mesh.
DE: 7260 Theory and modeling
DE: 7294 Instruments and techniques
DE: 7203 Body wave propagation
SC: Seismology [S]
MN: 2004 AGU Fall Meeting