Volume 14 Number 2
  • E-ISSN: 1365-2478



A brief review of the existing methods of gravity reduction is given and a new method suitable for use on high speed digital computers is described. The method is based on the formula for the gravitational attraction of a frustum of a cone. The topographic contours are represented by polygons and the and coordinates of corners of the polygons constitute the input to the computer. The vertical component of the gravitational attraction is calculated by evaluating the cone formula for a number of vertical sections of the topography. Each vertical section is simplified by adopting a procedure of grouping and averaging for the distant points of the section. The effect of the earth's sphericity is taken into account by lowering the distant points of the sections by amounts determined by the curvature. The computations include the area close to the point at which the attraction is required and may be limited to an area defined by a circle centered at this point. The method is therefore compatible with the conventional zone chart methods.

As an illustration of the method the gravitational attraction of Caryn Seamount in the Atlantic Ocean is computed. The total Bouguer correction and the Terrain correction are also computed for an area in northwestern South America and comparisons are made with hand computations by a zone chart method. As an example, for work at sea, the Bouguer corrections for an area near the Island of Mauritius in the Indian Ocean are computed and the effects of sphericity and three‐dimensionality are calculated.

The gravitational attraction of two‐dimensional bodies can be computed in a very similar manner. The attraction of the Puerto Rico Trench model is computed and the results are compared with other methods. The effects of sphericity and assumptions involved in extending the models to infinity are discussed.


Article metrics loading...

Loading full text...

Full text loading...


  1. Bott, M.H.P.1959The Use of Electronic Digital Computers for the Evaluation of Gravimetric Terrain Correction. Geophys. Prosp. 7, No. 1, p. 45–54.
    [Google Scholar]
  2. Bullard, E. C.1936Gravity Measurements in East Africa. Trans. Roy. Soc. (Lond.) Ser. A 235, p. 445–531.
    [Google Scholar]
  3. Collette, B. J.1965Charts for Determining the Gravity Effect of Two and Three‐dimensional Bodies bounded by Arbitrary Polygons. Geophys. Prosp. 13, No. 1, p 12–21.
    [Google Scholar]
  4. Fisher, R. L., Heezen, B. C. and Johnson, G. L.III. The Mascarene Plateau (in press).
  5. Gassmann, F.1951Graphical Evaluation of the Anomalies of Gravity and of the Magnetic Field caused by Three‐dimensional Bodies. Proc. Third World Petroleum Congress Sec. 1, p. 613–621.
    [Google Scholar]
  6. Gimlett, J. I.1964A Computer Method for Calculating Complete Bouguer Corrections with Varying Surface Density. Computers in the Mineral Industries Part 1. Stanford University Publications, Geological Sciences 9, No. 1. Editor G. A. Parks.
    [Google Scholar]
  7. Hammer, S.1939Terrain Corrections for Gravimetric Stations. Geophys. 4, No. 3, p. 184–194.
    [Google Scholar]
  8. Hayford, J. F. and Bowie, W.1912The Effect of Topography and Isostatic Compensation upon the Intensity of Gravity, USCGS, Spec. Publ. No. 10 Washington .
    [Google Scholar]
  9. Heiskanen, W. A., and Vening Meinesz, F. A.1958The Earth and its Gravity Field. McGraw‐Hill Book Co. Inc.
    [Google Scholar]
  10. Kane, M. F.1964A Comprehensive System of Terrain Corrections using a Digital Computer. Computers in the. Mineral Industries Part 1. Stanford University Publications, Geological Sciences 9, No. 1. Editor G. A. Parks.
    [Google Scholar]
  11. Lejay, R. P. P.1947Développements Modernes de la Gravimétric Paris Gauthier‐Villars, Imprimeur‐Editeur.
    [Google Scholar]
  12. Miller, E. T. and Ewing, M.1956Geomagnetic Measurements in the Gulf of Mexico and in the Vicinity of Caryn Peak. Geophysics21, No. 2, p. 406–432.
    [Google Scholar]
  13. Talwani, M., Worzel, J. L. and Landisman, M.1959Rapid Gravity Computations for Two‐dimensional Bodies with Application to the Mendocino Submarine Fracture Zone. Jour. Geophys. Res. 64, No. 10, p. 49–59.
    [Google Scholar]
  14. Talwani, M., Sutton, G. H., and Worzel, J. L.1959bA Crustal Section across the Puerto Rico Trench. Jour. Geophys. Res. 64, No. 10, p. 1545–1555.
    [Google Scholar]
  15. Talwani, M. and Ewing, M.1960Rapid Computation of Gravitational Attraction of Three‐dimensional Bodies of Arbitrary Shape. Geophysics25, No. 1, p. 203–225.
    [Google Scholar]
  16. Talwani, M.1965Computation with the Help of a Digital Computer of Magnetic Anomalies Caused by Bodies of Arbitrary Shape. Geophysics30, No. 5, p. 797–817.
    [Google Scholar]
  17. Vening Meinesz, F. A., Umbgrove, J. H. F., and Kuenen, Ph. H.1934Gravity Expeditions at Sea, 1923–1932. Publ. Neth. Geod. Comm., Delft 2.
  • Article Type: Research Article
This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error