Azimuthal AVO and curvature

Jesse M. Kolb, David Cho, Kristopher A. Innanen

Azimuthal AVO can be used to determine anisotropic elastic parameters in the subsurface. AVO methods often separate the effects of elastic parameters on the reflection coefficient into three terms: intercept, gradient, and curvature. In this paper we show that the gradient is characterized by multiple independent terms that change with azimuth, leading to nonuniqueness when used to characterize anisotropy, while the curvature term is only influenced by a single term proportional to the change in horizontal P-wave velocity across the interface along an azimuth. This gives the curvature the capability of determining anisotropy without ambiguity and makes it a useful quantity to estimate, especially when it is combined with the gradient.