Potential‐field continuation: Past practice vs. modern methods

Xia et al. (1993) offer an excellent method for potential‐field continuation between irregular surfaces by applying the equivalent source technique. This method has proven to be the fastest and most stable procedure for solving the problem of reducing potential‐field data to a constant datum (e.g., Pail, 1995) as long as no sources exist between observation surface and the equivalent stratum. The authors suggest using special equations for the continuation of magnetic fields. Theoretically this is correct, but neither necessary nor well suited, because of the characteristics of the operator for magnetic fields applied in the wavenumber domain.

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Potential field continuation between arbitrary surfaces — Comparing methods

Geophysics ◽

10.1190/geo2016-0210.1 ◽

2017 ◽

Vol 82 (3) ◽

pp. J9-J25 ◽

Cited By ~ 6

Author(s):

Mark Pilkington ◽

Olivier Boulanger

Keyword(s):

Potential Field ◽

Horizontal Plane ◽

Real Data ◽

Continuation Methods ◽

Source Distribution ◽

Potential Field Data ◽

Low Pass ◽

Equivalent Sources ◽

Intermediate Surface ◽

Field Continuation

The continuation of potential field data from one irregular surface to another, not always horizontal, is often a necessary component within the data processing and interpretation stream. The most common requirement is to reduce field values (or some related component or derivative) to a horizontal plane, to facilitate further quantitative processing. Methods available to continue data comprise two main approaches. The first (source-based) involves calculating a source distribution that produces a fit to the data and can be used to calculate the field at any other point above. The second (field-based) requires no source determinations and deals with only fields but may involve calculating the field on some intermediate surface. Nine different continuation methods were compared (four source based and five field based) through synthetic tests and on real data from a helicopter-borne survey in Yukon, Canada. The preferred methods of Guspi and Hansen are those that do not involve any theoretical or geometric approximations and involve intermediate calculations on a plane or surface close to the observation surface. The Guspi approach is faster, based on using frequency-domain processing, but the Hansen method uses equivalent sources close enough to and consistently below the observation surface so that no low-pass filtering needs to be used.

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On: “Geophysical Analysis in Central Indiana using Potential Field Continuation,” by A. J. Rudman, Judson Mead, Joseph F. Whaley, and Robert F. Blakely (GEOPHYSICS, October 1971, p. 878–890)

Geophysics ◽

10.1190/1.1440316 ◽

1972 ◽

Vol 37 (6) ◽

pp. 1047-1047

Author(s):

Douglas J. Guion

Keyword(s):

Gravity Anomaly ◽

Magnetic Anomaly ◽

Potential Field ◽

Downward Continuation ◽

Gravity Effect ◽

Gravity And Magnetic ◽

Gravity And Magnetic Anomaly ◽

Field Continuation ◽

Hamilton County

I read with interest the article concerning modeling the Hamilton County, Indiana, gravity and magnetic anomaly. The authors’ method for outlining the igneous body by downward continuation aroused my curiosity to the point that I decided to study the results in detail. My investigation revealed that the calculated gravity effect of the model did not satisfy the observed gravity anomaly. In fact, the amount of mismatch is quite serious.

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