In this paper, we present results of the study for application of the combination of derivatives of directional analytic signals of the magnetic tensor gradient and maximum horizontal gradient to determine the edges of the sources through the Edge-Detector function (|ED|). Algorithms and programs written in the Matlab language have been used for testing the calculation on 3D models in correlative comparison with the method using the amplitude function of analytic signals. The calculation results showed the advantages of the |ED| function and its applicability in determing the boundaries of sources of magnetic anomaly. | VNU Journal of Science: Mathematics – Physics, Vol. 33, No. 4 (2017) 24-35 Using the Directional Analytic Signals of Magnetic Gradient Tensor to Determine Boundaries of Source Nguyen Thi Thu Hang1, Pham Thanh Luan1, Do Duc Thanh1,*, Le Huy Minh2 1 2 VNU University of Science, 334 Nguyen Trai, Thanh Xuan, Hanoi, Vietnam Institute of Geophysics, VAST, 18 Hoang Quoc Viet, Cau Giay, Hanoi, Vietnam Received 23 August 2017 Revised 19 October 2017; Accepted 23 October 2017 Abstract: The analytic signals of the magnetic tensor gradient within two- and three-dimensional space domain can be applied as a useful tool to estimate the depth and position of magnetic sources because their values only depend on location but not on magnetization direction of the sources of the magnetic anomaly. In this paper, we present results of the study for application of the combination of derivatives of directional analytic signals of the magnetic tensor gradient and maximum horizontal gradient to determine the edges of the sources through the Edge-Detector function (|ED|). Algorithms and programs written in the Matlab language have been used for testing the calculation on 3D models in correlative comparison with the method using the amplitude function of analytic signals. The calculation results showed the advantages of the |ED| function and its applicability in determing the boundaries of sources of magnetic anomaly. Keywords: Analytic signal, magnetic tensor gradient, Edge-detector, |ED|. 1. Introduction In magnetic exploration, the quantitative interpretation or solving of an inverse problem to determine the position, shape, depth, magnetization of geological objects causing observed anomalies always plays an important role. It was performed by many different methods: Euler deconvolution method ([1-3]), 2D and 3D selection method ([4, 5]), etc. With its advantages in recent years, the use of analytic signal to interpret data has attracted the attention of many geophysicists in the .
