Estimating T e in the presence of internal loads

Many attempts have been made to estimate the effective elastic thickness T e of the continental lithosphere from the relationship between the Fourier transforms of gravity and topography. If internal loads are ignored, a simple model with values of T e of between 5 and 25 km fits most of the observations. If internal loads with topographic expression are present, the simple model of topographic loading underestimates the true value of T e , potentially by a large factor. This difficulty can be avoided by using the coherence γ B 2 between the Bouguer gravity and topography to estimate T e . However, erosion and sedimentation can produce loads that are not associated with any topography. If T e is estimated from γ B 2 when such loads are important, the value of T e is overestimated, again potentially by a large factor. The only obvious solution to these problems is to use a simple model that can describe all three types of loads, surface loads, internal loads with topographic expression, and loads with no topographic expression, and to estimate their contributions at the same time as T e is determined. The parameters of such a model are estimated from several data sets and show that there are no significant internal loads with topographic expression in any of the seven continental regions discussed here and that none give values of T e greater than 25 km.