Geophysical inversion of on board satellite gradiometer data — A feasibility study in the ALPACA region, Central Europe

Abstract

The structure of the lithosphere of the ALPACA (Alpine-Pannonian-Carpathian) region is described by a model containing about 200000 rectangular volume elements (prisms) of variable dimensions defined in the mapping system of Hungary. Forward computations show that the contribution of the structural units (topography and upper mantle) of the lithosphere to the disturbing potential T of the Earth may reach several tenths of E unit at 300 km elevation. The contribution from the sediments is less by a factor of ten but even its magnitude exceeds the planned sensitivity of the satellite on board measurements. It is expected that some regional information about the horizontal density variation of the crust can be deduced from the GOCE data, especially for the density contrast between the lower crust and upper mantle. Since the density distribution of either the topographical masses or the sedimentary complex is much better known than the density jump on the Moho, therefore their effect on the second derivatives of T can be removed from the measurements. The residuals can be interpreted by inversion using the closed analytical formulae available for rectangular volume elements. The modelling approach based on the local planar co-ordinate frame was compared to the polyhedron representation of the same crustal model defined in a global rectangular co-ordinate system. No significant effect of the Earths curva-ture could be indicated for the Moho interface.