OPTIMAL TOPOGRAPHIC - ISOSTATIC CRUST MODELS FOR GLOBAL GEOPOTENTIAL INTERPRETATION

Abstract

The topographic-isostatic potential of the earth's crust can be computed easily using average crustal density parameters, a global isostatic model and a numerical dataset of mean continental and oceanic heights. In lack of the detailed data for density, crustal thickness and isostatic compensation, a least squares estimation is suggested to determine global horizontal variation of crustal parameters. These variations can be determined using a minimum principle to yield a minimum variance high frequency residual geoid. The basic mathematical tool for the determina- tion of such parameter variation functions is the Clebsch-Gordan product-sum conversion formula of spherical harmonics. Computer programs were developed based on the above mentioned mathematical algorithm to determine optimal linear topographic-isostatic crust models (OLTM). Previ- ous calculations detected significant global density variations inside the crust with respect to the simple Airy model of uniform crustal parameters. The result would perhaps show us a better insight into the global isostatic behaviour of the crust.