The Improved Anisotropy Normalized Variance for Detecting Non‐Vertical Magnetization Anomalies

Abstract

For the magnetic field with unknown magnetization direction, it is necessary to study the edge detection for the magnetic source of oblique magnetization directly. In this study, we propose a new edge detection called anisotropy normalized variance based on magnetic gradient tensor (ANV_MGT). First we use an anisotropy scale to improve the core function of ANV to show the effect of the anisotropy Gaussian function. Then the magnetic gradient tensor mode is used in the ANV method to process the anomalies with oblique magnetization. We construct a numerical model of complex magnetic anomalies with an oblique magnetization, which is used to test the edge detection method. The model test shows that the proposed method, ANV_MGT, can detect the edge of the magnetic source with non‐vertical magnetization direction. It also shows that the proposed method is better than application of ANV on the 3D analytic signal amplitude. In the application to real data from western China, a perfect magnetite ore location is determined by performing ANV_MGT for the non‐reduction to the pole data.