A one-way dual-domain propagator for scalar qP-waves in VTI media

Abstract

In this paper, we present an anisotropic one-way propagator for modeling and imaging quasi-P (qP) waves in transversely isotropic media with a vertically symmetric axis (VTI media). We derive the dispersion relation for a scalar qP-wave using elastic wave equations for anisotropic media. By applying a rational approximation to the dispersion relation, we obtain a one-way, dual-domain, scalar qP-wave propagator for heterogeneous VTI media. The propagator includes a phase-shift term and both phase-screen and large-angle correction terms. The phase-shift term is implemented in the wavenumber domain, while the other terms are implemented in the space domain. Fourier transformations are used to shuttle the wavefield between the two domains. This propagator can be used to propagate qP-wavefields within an isotropic or a VTI medium, with either medium containing lateral heterogeneities. Error analysis of the impulse response and dispersion relations demonstrates that the propagator is accurate and stable and has a wide-angle capability. The application of the propagator to the imaging of qP-wave data with VTI models which contain complex structures and large perturbations of velocity and anisotropy results in excellent image quality. This demonstrates the potential value of the propagator for use in modeling and imaging qP-wavefields within strongly heterogeneous VTI media.