GRAVITATIONAL FIELDS OF EARTH MODELS AND THE STRUCTURE OF THE EARTH'S INTERIOR
RAND CORP SANTA MONICA CA
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The third zonal harmonic J3 of the earths potential field, contributes a pear-shaped component to its field configuration. The cause has not been definitely established. In an earlier study, the gravitational fields of earth models were calculated to determine whether the distinct variations in mass distribution that exist between oceanic and continental crustal blocks could account for the third zonal harmonic. The results obtained from those models led to the construction of a second set of models the results are presented. The second set of earth models incorporates conventional crustal structures and an uppermost mantle structure based on seismic evidence regarding Gutenbergs low-velocity layer. The depths of isostatic compensation considered were 200 and 300 km. The models produced negative surface-gravity anomalies over continental blocks, whose magnitude increased slightly as depth to compensation increased. Corresponding to the general distribution of oceans and continents, these anomalies are comparable in magnitude and agree in sign with the satellite-derived anomaly.
- Geology, Geochemistry and Mineralogy