The partial derivatives of travel time or amplitude with respect to model parameters are referred to as perturbations. Explicit equations for the spatial derivatives and perturbations of amplitude in both isotropic and anisotropic media are derived. The spatial derivatives and perturbations of the logarithm of amplitude can be calculated by numerical quadratures along rays.
Ray theory, amplitude, transport equation, paraxial approximation, perturbation methods, inhomogeneous media, seismic anisotropy.
The image of the paper in GIF 150dpi (559 kB) is designed for an instant screen preview.
The paper is available in PostScript (128 kB) and GZIPped PostScript (47 kB).