A comprehensive system of automatic computation in magnetic and gravity interpretation

Geophysics
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Abstract

In the interpretation of magnetic and gravity anomalies, downward continuation of fields and calculation of first and second vertical derivatives of fields have been recognized as effective means for bringing into focus the latent diagnostic features of the data. A comprehensive system has been devised for the calculation of any or all of these derived fields on modern electronic digital computing equipment. The integral for analytic continuation above the plane is used with a Lagrange extrapolation polynomial to derive a general determinantal expression from which the field at depth and the various derivatives on the surface and at depth can be obtained. It is shown that the general formula includes as special cases some of the formulas appearing in the literature. The process involves a "once for all depths" summing of grid values on a system of concentric circles about each point followed by application of the appropriate one or more of the 19 sets of coefficients derived for the purpose. Theoretical and observed multilevel data are used to illustrate the processes and to discuss the errors. The coefficients can be used for less extensive computations on a desk calculator. 

Publication type Article
Publication Subtype Journal Article
Title A comprehensive system of automatic computation in magnetic and gravity interpretation
Series title Geophysics
DOI 10.1190/1.1438736
Volume 25
Issue 3
Year Published 1960
Language English
Publisher Society of Exploration Geophysicists
Description 17 p.
First page 569
Last page 585
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