SOME IMPLICATIONS OF THE EARTH'S GRAVITATIONAL FIELD FOR THE INTERNAL STRUCTURE OF THE EARTH
Abstract
The configuration of the earth's potential field was determined from the orbits of near-earth satellites. This potential can be represented by a series expansion in spherical harmonics. The values of certain coefficients (J sub n) for terms in this series have been calculated. The J2 coefficient reflects the oblateness of the earth; the cause of the J3 coefficient was not established. The potential field can be expressed by surface gravity anomalies resulting from inhomogeneities in mass distribution within a body. Such differences in mass distribution exist between oceanic and continental areas within the crust and upper mantle over large areas of the earth's surface. Results are presented of an investigation of the gravitational fields of earth models performed to determine the nature of gravity anomalies to be expected from oceanic and continental areas. Using conventional crustal structure, the earth-model results indicate that a surface anomaly exists which is positive over continental blocks, and that its magnitude increases with increase in the assumed depth to isostatic compensation and with increase in positive topographic relief. Application of the earth-model anomaly to the actual distribution of continents and oceans results in a calculated value for the gravitational anomaly which is of the same order of magnitude as, but of opposite sign to, that derived from satellite orbits. Conditions that might reconcile this discrepancy are presented. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 01, 1962
- Accession Number
- AD0284630
Entities
People
- D. Oberste-lehn
Organizations
- RAND Corporation