Estimates of [formula omitted] for continental regions using GOCE gravity

Abstract

Satellite-only gravity fields and surface gravity obtained from altimetric measurements now agree well at wavelengths greater than ∼180 km. Satellite gravity fields can therefore be used to estimate the elastic thickness Te in regions where surface observations are sparse. They are used for this purpose in a number of continental regions, of India, Africa, and Antarctica, where the topography is sufficiently rough, and also in regions of the USA, China, Australia and Siberia, where there are surface measurements. Estimates of Te for Antarctica depend on measurements of ice thickness, which are now available for much of the continent. Values of Te are obtained using two methods: from the admittance between the free air gravity and the topography, and from the coherence between Bouguer gravity anomalies and the topography. The first, but not the second, gives values of Te that are everywhere less than the seismogenic thickness. Where there is sufficient topography, estimates of Te from PreCambrian shields are all greater than 10 km and do not correlate with the lithospheric thickness. They are probably are governed by variations in crustal heat generation rates. Values for regions strongly affected by Phanerozoic tectonics are all less than 7 km, and all such regions are underlain by thin lithosphere.