The Discrimination of Depth Estimates Using Curvatures and Source Parameters

The depth of isolated gravity and magnetic sources can be calculated with the curvature of special functions applied to the gravity or magnetic anomalies. This “curvature method” has been published by several authors and this paper investigates two ways to improve the validity of the results. The first way is to assess the local 2D conditions by evaluating the local shape of the special function. The proposed Shape Angle is calculated with the curvatures of the special function in two orthogonal directions. It is well suited to infer the quality of depth estimates because non-ideal sources will distort the ideal cylindrical shape of the special function. The second approach to discriminate between reliable depth estimates and spurious ones is to calculate source parameters associated with the estimate. Since the result is attached to a specific type of source, the application of the curvature method to the wrong type returns abnormal values of these parameters that can be easily discarded when compared with expected values. These discrimination techniques are tested on synthetic models and to gravity gradiometry data acquired in Pennsylvania, USA.