HR: 0830h
AN: S11C-0306    [PDF]
TI: One-way Wave Propagator Applied to Imaging in Heterogeneous Anisotropic Media
AU: * Han, Q
EM: qhan@es.ucsc.edu
AF: Modeling and Imaging Laboratory, IGPP,University of California, Santa Cruz, 1156 High St., UC Santa Cruz, Santa Cruz, CA 95064
AU: Wu, R
EM: wrs@es.ucsc.edu
AF: Modeling and Imaging Laboratory, IGPP,University of California, Santa Cruz, 1156 High St., UC Santa Cruz, Santa Cruz, CA 95064
AB: Travel time and amplitude errors produced by isotropic propagators applied to wave propagation problems in anisotropic media can not be neglected. Much effort has been spent on wave propagation problems in anisotropic media based on ray theory. Wave equation based methods have good accuracy and can be employed to propagate wave field in arbitrary complex media. One-way wave equation based methods are very efficient in modeling and imaging for transversely isotropic solids with a vertically symmetric axis (VTI) which is the most common case of anisotropy media. However, one-way wave equation methods usually suffer limitations of small propagation angles and weak perturbations of media parameters. Recently we developed an anisotropic one-way propagator that is efficient and accurate for any large isotropic and anisotropic perturbations. Based on elastic wave equations in anisotropic media we first separated the scalar qP-wave from qSV- and qSH-waves and derived dispersion relation of scalar qP-wave. Applied rational approximation to the dispersion relation we obtained approximate dispersion relation and the one-way dual-domain scalar P-wave propagator for modeling and imaging in heterogeneous VTI media. The propagator includes phase-shift term, phase-screen and large angle correction terms. The phase-shift term is implemented in wave number domain and the other terms are implemented in space domain. Fast Fourier transformation is employed for shuttling wave field between the two domains. The propagator can be used to extrapolate P-wave fields in isotropic or VTI background with strong isotropic or VTI perturbations. The results of impulse response and dispersion relation prove that the propagator has good accuracy, stability and wide-angle capacity even for strong velocity perturbations and anisotropy perturbations up to several times of the background medium. We applied the propagator to wave propagation and imaging in anisotropic models with complex structures. The model shows a number of challenging features to one-way propagators. Imaging results show that the propagator gives very satisfied results. Not only the structure is reconstructed clearly, but also the steep faults are correctly imaged.
DE: 7203 Body wave propagation
DE: 7260 Theory and modeling
SC: Seismology [S]
MN: 2003 Fall Meeting