AVO/AVA Attribute Designed to extract gradient, intercept and curvature from pre-stack seismic gathers. Also when there are noise gathers, the curved-surface function can be applied to extract the attributes to consider both the seismic amplitude-vs.-offset and amplitude-vs.-time. These AVO attributes can be integrated into other attributes for geostatistical inversion. Compressional Velociy, Shear Velocity and Density can be calculated from AVO angle gathers based on Conjugate Gradient methods.