COMPENSATION OF OCEANIC TOPOGRAPHY - APPLICATION OF THE RESPONSE FUNCTION TECHNIQUE TO THE SURVEYOR AREA

The compensation of young oceanic topography produced by sea floor spreading at the Juan de Fuca Ridge crest is analysed using the response function approach of Dorman and Lewis. The first- order correlation between gravity g and topography h is best explained by a regional compensation mechanism corresponding to a rather weak elastic plate with flexural rigidity equal to 5 times 1020 N m and a crustal thickness of 10 km. The second-order terms calculated from the correlation between gravity and the square of the topography suggest an even weaker plate with shallower compensation. The earth's response to topographic loads appears to have the expected isotropic from, because for most wavelengths the correlation between g and h is independent of azimuth. A slight anisotropy at about 50-km wave-length is unexplained, but it is most likely due to variations in crustal density and/or thickness. The compensation for topography produced by the E Pacific Rise is remarkably similar to that found for the Juan de Fuca Ridge, in spite of gross dissimilarities in spreading rates, total ridge crest length, and plate size.-Author