Special Issue: Applications and Interpretation of Modern Magnetic Surveys
- Open Access
Can we estimate total magnetization directions from aeromagnetic data using Helbig’s integrals?
Earth, Planets and Space volume 57, pages681–689(2005)
An algorithm that implements Helbig’s (1963) integrals for estimating the vector components (mx, my, mz) of the magnetic dipole moment from the first order moments of the vector magnetic field components (ΔX, ΔY, ΔZ) is tested on real and synthetic data. After a grid of total field aeromagnetic data is converted to vector component grids using Fourier filtering, Helbig’s infinite integrals are evaluated as finite integrals in small moving windows using a quadrature algorithm based on the 2-D trapezoidal rule. Prior to integration, best-fit planar surfaces must be removed from the component data within the data windows in order to make the results independent of the coordinate system origin. Two different approaches are described for interpreting the results of the integration. In the “direct” method, results from pairs of different window sizes are compared to identify grid nodes where the angular difference between solutions is small. These solutions provide valid estimates of total magnetization directions for compact sources such as spheres or dipoles, but not for horizontally elongated or 2-D sources. In the “indirect” method, which is more forgiving of source geometry, results of the quadrature analysis are scanned for solutions that are parallel to a specified total magnetization direction.
Bhattacharyya, B. K., A method for computing the total magnetization vector and the dimensions of a rectangular block-shaped body from magnetic anomalies, Geophysics, 31, 74–96, 1966.
Blakely, R. J., Potential Theory in Gravity and Magnetic Applications, Cambridge University Press, Cambridge, 441 pp., 1995.
Emilia, D. A. and R. L. Massey, Magnetization estimation for nonuniformly magnetized seamounts, Geophysics, 39, 223–321, 1974.
Helbig, K., Some integrals of magnetic anomalies and their relation to the parameters of the disturbing body, Zeitschrift für Geophysik, 29(2), 83–96, 1963.
Lourenco, J. S. and H. F. Morrison, Vector magnetic anomalies derived from measurements of a single component of the field, Geophysics, 38(2), 359–368, 1973.
Macmillian, S., S. Maus, T. Bondar, A. Chambodut, V. Golovkov, R. Holme, B. Langlais, V. Lesur, F. Lowes, H. Lühr, W. Mai, M. Mandea, N. Olsen, M. Rother, T. Sabaka, A. Thomson, and I. Wardinski, Ninth generation International Geomagnetic Reference Field released, EOS, Transactions, American Geophysical Union, 84(46), 503, 18 November 2003.
McCracken, D. D. and W. S. Dorn, Numerical Methods and Fortran Programming, John Wiley and Sons, Inc., New York, 457 pp., 1964.
Mederios, W. E. and J. B. C. Silva, Simultaneous estimation of total magnetization direction and 3-D spatial orientation, Geophysics, 60(5), 1365–1377, 1995.
Parker, R. L., L. Shure, and J. A. Hildebrand, The application of inverse theory to seamount magnetism, Rev. Geophys., 25, 17–40, 1987.
Rajagopalan, S., P. Schmidt, and D. Clark, Rock magnetism and geophysical interpretation of the Black Hill Norite, South Australia, Exploration Geophysics, 24, 209–212, 1993.
Rao, B. S. R., T. K. S. Prakasa Rao, and A. S. Krishna Murthy, A note on magnetized spheres, Geophys. Prosp., 25, 746–757, 1977.
Schmidt, P. W. and D. A. Clark, Directions of magnetization and vector anomalies derived from total field surveys, Preview, 70, 30–32, 1997.
Schmidt, P. W. and D. A. Clark, The calculation of magnetic components and moments from TMI: A case history from the Tuckers igneous complex, Queensland, Exploration Geophysics, 29, 609–614, 1998.
Schnetzler, C. C. and P. T. Taylor, Evaluation of an observational method for estimation of remanent magnetization, Geophysics, 49, 282–290, 1984.
U.S. Geological Survey and Sander Geophysics, Ltd., Digital data from the Isleta-Kirtland aeromagnetic survey, collected south of Albuquerque, New Mexico, U.S. Geological Survey Open-File Report 98-341 (CD-ROM), 1998.
About this article
Cite this article
Phillips, J.D. Can we estimate total magnetization directions from aeromagnetic data using Helbig’s integrals?. Earth Planet Sp 57, 681–689 (2005). https://doi.org/10.1186/BF03351848