THE MINIMUM DEPTH OF COMPENSATION OF TOPOGRAPHIC MASSES

Based on the recently compiled crustal-thickness data, it is shown that the Airy-Heiskanen model of compensation only partly compensates the surface topographic masses. To fit the external gravitational potential induced by the surface topography, the Pratt-Hayford concept of compensation has also to be considered. Employing the dynamical flattening of the Earth, the minimum depth of compensation has been estimated to be of the order of 100-150 km. This means that the topographic masses are compensated throughout the Earth's lithosphere at least.