Full magnetic gradient tensor from triaxial aeromagnetic gradient measurements: Calculation and application
Luo Yao1,2, Wu Mei-Ping1, Wang Ping2, Duan Shu-Ling2, Liu Hao-Jun2, Wang Jin-Long2, and An Zhan-Feng2
1. College of Mechatronics Engineering and Automation, National University of Defense Technology, Changsha 410073, China. 2. China Aero Geophysical Survey and Remote Sensing Center for Land and Resources, Beijing 100083, China.
Abstract：
The full magnetic gradient tensor (MGT) refers to the spatial change rate of the three field components of the geomagnetic field vector along three mutually orthogonal axes. The tensor is of use to geological mapping, resources exploration, magnetic navigation, and others. However, it is very difficult to measure the full magnetic tensor gradient using existing engineering technology. We present a method to use triaxial aeromagnetic gradient measurements for deriving the full MGT. The method uses the triaxial gradient data and makes full use of the variation of the magnetic anomaly modulus in three dimensions to obtain a self-consistent magnetic tensor gradient. Numerical simulations show that the full MGT data obtained with the proposed method are of high precision and satisfy the requirements of data processing. We selected triaxial aeromagnetic gradient data from the Hebei Province for calculating the full MGT. Data processing shows that using triaxial tensor gradient data allows to take advantage of the spatial rate of change of the total field in three dimensions and suppresses part of the independent noise in the aeromagnetic gradient. The calculated tensor components have improved resolution, and the transformed full tensor gradient satisfies the requirement of geological mapping and interpretation.
Luo Yao,Wu Mei-Ping,Wang Ping et al. Full magnetic gradient tensor from triaxial aeromagnetic gradient measurements: Calculation and application[J]. APPLIED GEOPHYSICS, 2015, 12(3): 283-291.
[1]
Blakely, R. J., 1996, Potential theory in gravity and magnetic applications: Cambridge University Press.
[2]
Chai, Y. P., 2009, A-E equation of potential field transformations in the wavenumber domain and its application: Applied Geophysics, 6(3), 205−216.
[3]
Clark, D. A., 2013, New methods for interpretation of magnetic vector and gradient tensor data II: application to the Mount Leyshon anomaly, Queensland, Australia: Exploration Geophysics, 44(2), 114−127.
[4]
Guo, Z. H., Guan, Z. N., and Xiong, S. Q., 2004, Cuboid ΔΤ and its gradient forward theoretical expressions without analytic odd points: Chinese J. Geophys. (in Chinese), 47(6), 1131−1138.
[5]
Hood, P. J., and Teskey, D. J., 1989, Aeromagnetic gradiometer program of the Geological Survey of Canada: Geophysics, 54(8), 1012−1022.
[6]
Hardwick, C. D., 1996, Aeromagnetic gradiometry in 1995: Exploration Geophysics, 27(1), 1-11.
[7]
Luo, Y., and Yao, C. L., 2007, Theoretical study on cuboid magnetic field and its gradient expression without analytic singular point: Oil Geophysical Prospecting (in Chinese), 42(6), 714−719.
[8]
Nelson, J. B., 1988, Calculation of the magnetic gradient tensor from total field gradient measurements and its application to geophysical interpretation: Geophysics, 53(7), 957-966.
[9]
Pedersen, L. B., and Rasmussen, T. M., 1990, The gradient tensor of potential field anomalies: Some implications on data collection and data processing of maps: Geophysics, 55(12), 1558-1566.
[10]
Stolz, R., Zakosarenko, V., Schulz, M., Chwala, A., Fritzsch, L., Meyer, H., -G., and Köstlin, E., O., 2006, Magnetic full-tensor SQUID gradiometer system for geophysical applications: The Leading Edge, 25(2), 178-180.
[11]
Schmidt, P. W., and Clark, D. A., 2006, The magnetic gradient tensor: Its properties and uses in source characterization: The Leading Edge, 25(1), 75-78.
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