Structural Trend
The options on the Implicit tab, in the Structural Trend group, allow you to create and display locally varying anisotropic models based on a surface.
A 3D geological model with locally varying anisotropy (LVA) is calculated based upon the modified distance/covariance between locations in space. Typically, a straight line path determines distance, but in the absence of linear features a path between locations is determined by tracing along features.