Technical Papers - Airborne Magnetics

Gridding Aeromagnetic Data Using Longitudinal and Transverse Horizontal Gradients with the Minimum Curvature Operator

Michael D. O’Connell, Consultant, 1679 Laurelwood Pl., Ottawa, Ontario, K1C 6Y4;
Richard S. Smith, Fugro Airborne Surveys, 2060 Walkley Road, Ottawa, Ontario, Canada, K1G 3P5; and
Marc A. Vallee, Fugro Airborne Surveys, 5610, Chemin Bois-Franc, St-Laurent, Montréal, Quebec, Canada H4S 1A9.

Abstract

The measurement of spatial gradients of the earth’s total magnetic field intensity has been advocated for many years. However, it is only in recent years that the collection of such data has become routine. One of the principal advantages of the measured gradients is that the horizontal gradients can improve the quality of the two-dimensional grid interpolated from the one-dimensional profile data. This is normally done by using the transverse horizontal gradient in a bi-directional gridding algorithm. The minimum curvature routine is considered by some workers to be superior to bi-directional gridding routines. We have modified the minimum curvature routine to use both the transverse and longitudinal horizontal gradients to enhance the quality of the grid.

Using both gradients improves the trending of features and better resolves the location and shapes of small isolated features. These improvements are most marked when the line spacing is broad compared with the wavelength of features present in the total field. In our field example, the grids generated with standard minimum curvature from traverse lines 150 m apart are comparable to grids obtained with gradient enhanced minimum curvature using lines 300 m apart.

Published in the Society of Exploration Geophysicists’ publication The Leading Edge, February 2005, Volume 24, issue 2, pages 142-145. See: http://segdl.org/tle/

Download Paper (818 Kb)