Dictionary:Nonhyperbolic normal-moveout (velocity) analysis
Analysis that allows for typical vertical changes in velocity and anisotropy when using long offsets, that is, where the offset exceeds the reflector depth. In this case the hyperbolic equation for a reflection can often be expressed as
where t0 is the zero-offset traveltime, x is offset, V is P-wave velocity, and where and are Thomsen anisotropic parameters (q.v.).
Use of the 4th-order term given by a Taylor expansion corrects for the undesirable "hockey-stick" effect.