Detecting edges of geological sources from gravity or magnetic anomalies through a novel algorithm based on the hyperbolic tangent function

Abstract

Directional derivative-based edge detectors are commonly used to outline the abrupt lateral variations in densities or magnetizations of geological sources from potential-field datasets. Some subtle traces of faults, lithological contacts, and lineaments can be made more visible on anomaly maps using these algorithms. However, these algorithms generally suffer from common limitations such as blurry edges with low resolution or faulty boundaries. To minimize these challenges, we propose a new efficient edge detector that benefits from the hyperbolic tangent function. The performance of this detector was tested on the responses of a synthetic gravity model and Bishop's complex magnetic model. Gaussian noise content was also added to both synthetic cases to test the response of the proposed operator. In a real-data experiment, residual gravity anomalies of the Aegean Graben System from western T & uuml;rkiye, obtained via finite element method, were used to delineate abrupt lateral variations in mass densities in the region. The traces of basin-bounding normal faults and the boundaries of major grabens were improved in the resultant image map. A modified nonlocal means filter was also applied in both synthetic and real-data cases to attenuate undesired high-frequency effects. The proposed edge detection operator produced satisfactory outputs in each case. Comparative studies performed with some traditional and recently introduced algorithms further showed the superiority of the operator; thus, this detector is useful in revealing geological features that cannot be easily seen in potential-field anomaly maps and it is a strong alternative to currently used algorithms.