Exploration Geophysics Exploration Geophysics Society
Journal of the Australian Society of Exploration Geophysicists

The use of curvature in potential-field interpretation*

Jeffrey D. Phillips 1 4 R. O. Hansen 2 Richard J. Blakely 3

1 US Geological Survey, Denver Federal Center, Box 25046, MS 964, Denver, CO 80225, USA.

2 EDCON-PRJ, Inc., 171 South Van Gordon Street, Suite E, Lakewood, CO 80228, USA.

3 US Geological Survey, 345 Middlefield Road, MS 989, Menlo Park, CA 94025, USA.

4 Corresponding author. Email: jeff@usgs.gov

Exploration Geophysics 38(2) 111-119 http://dx.doi.org/10.1071/EG07014
Submitted: 28 June 2006  Accepted: 27 April 2007   Published: 15 June 2007


Potential-field anomalies can be transformed into special functions that form peaks and ridges over isolated sources. All special functions have a common mathematical form over an isolated source, which leads to a common equation for estimating the source depth from the peak value and the curvature at the peak. Model-specific special functions, usually calculated from a transformed version of a potential field, are used to estimate the locations of very specific source types. Model-independent special functions calculated from an observed or transformed potential field can be used to estimate the locations of a variety of source types. Vertical integration is a particularly useful transformation for reducing the effects of noise and increasing the coherency of solutions from model-independent special functions. For gridded data, the eigenvalues and eigenvectors of the curvature matrix associated with a quadratic surface that is fitted to a special function within 3 × 3 windows can be used to locate the sources and estimate their depths and strikes. Discrete source locations estimated in this manner can be connected into lines that follow contacts, faults, and other mappable features based on distance and azimuth criteria. These concepts are demonstrated on aeromagnetic data from the Albuquerque basin of New Mexico, USA.

Key words: potential-field, interpretation, curvature, source-location, strike.


Blakely R. J. Simpson R. W. 1986 Approximating edges of source bodies from magnetic or gravity anomalies Geophysics 51 1494 1498 doi:10.1190/1.1442197

Cordell L. , and Grauch V. J. S. , 1985, Mapping basement magnetization zones from aeromagnetic data in the San Juan basin, New Mexico, in W. J. Hinze, ed., The Utility of Regional Gravity and Magnetic Anomaly Maps: Society of Exploration Geophysicists, 181–197.

Cordell L. McCafferty A. E. 1989 A terracing operator for physical property mapping with potential field data Geophysics 54 621 634 doi:10.1190/1.1442689

Grauch V. J. S. 2001 Using high-resolution aeromagnetic surveys to map subsurface hydrogeology in sediment-filled rift basins: a case study over the Rio Grande rift, central New Mexico, USA Exploration Geophysics 32 209 213

Hansen R. O. deRidder E. 2006 Linear feature analysis for aeromagnetic data Geophysics 71 L61 L67

Li X. 2006 Understanding the 3D analytic signal Geophysics 71 L13 L16 doi:10.1190/1.2184367

MacLeod I. N. Jones K. Dai T. F. 1993 3-D analytic signal in the interpretation of total magnetic field data at low magnetic latitudes Exploration Geophysics 24 679 688

Nabighian M. N. 1972 The analytic signal of two-dimensional magnetic bodies with polygonal cross-section: its properties and use for automated anomaly interpretation Geophysics 37 507 517

Phillips J. D. , 2000, Locating magnetic contacts: a comparison of the horizontal gradient, analytic signal, and local wavenumber methods: Society of Exploration Geophysicists, Expanded Abstracts, 2000 Technical Program, 1, 402–405.

Pilkington M. Keating P. 2004 Contact mapping from gridded magnetic data—a comparison of techniques Exploration Geophysics 35 306 311

Pilkington M. Keating P. 2006 The relationship between local wavenumber and analytic signal in magnetic interpretation Geophysics 71 L1 L3

Reid A. B. Allsop J. M. Granser H. Millett A. J. Somerton I. W. 1990 Magnetic interpretation in three dimensions using Euler deconvolution Geophysics 55 80 91 doi:10.1190/1.1442774

Roberts A. 2001 Curvature attributes and their application to 3D interpreted horizons First Break 19 85 100 doi:10.1046/j.0263-5046.2001.00142.x

Roest W. R. Pilkington M. 1993 Identifying remanent magnetization effects in magnetic data Geophysics 58 653 659 doi:10.1190/1.1443449

Roest W. R. Verhoef J. Pilkington M. 1992 Magnetic interpretation using the 3-D analytic signal Geophysics 57 116 125 doi:10.1190/1.1443174

Smith R. S. Thurston J. B. Dai T.-F. MacLeod I. N. 1998 iSPI—the improved source parameter imaging method Geophys. Prosp. 46 141 151

Smith R. S. Salem A. Lemieus J. 2005 An enhanced method for source parameter imaging of magnetic data collected for mineral exploration Geophys. Prosp. 53 655 665

Sweeney R. E. , Grauch V. J. S. , and Phillips J. D. 2002, Merged digital aeromagnetic data for the Albuquerque and southern Espanola Basins, New Mexico: US Geological Survey Open-File Report 02-205. http://pubs.usgs.gov/of/2002/ofr-02-0205/

Thurston J. B. Smith R. S. 1997 Automatic conversion of magnetic data to depth, dip, and susceptibility contrast using the SPI method Geophysics 62 807 813 doi:10.1190/1.1444190

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