Journal Title
Title of Journal: Stud Geophys Geod
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Abbravation: Studia Geophysica et Geodaetica
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Publisher
Springer Netherlands
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Authors: Mohammad Bagherbandi Lars E Sjöberg
Publish Date: 2011/09/01
Volume: 55, Issue: 4, Pages: 641-
Abstract
The goal of this article is to compare the AiryHeiskanen and Vening MeineszMoritz VMM gravimetric models for determining Moho depth with the seismic Moho CRUST20 or SM model Numerical comparisons are performed globally as well as for some geophysically interesting areas such as Fennoscandia Persia Tibet Canada and Chile These areas are most complicated areas in view of rough topography Tibet Persia and Peru and Chile postglacial rebound Fennoscandia and Canada and tectonic activities PersiaThe mean Moho depth provided by CRUST20 is 229 ± 01 km Using a constant Moho density contrast of 06 g/cm3 the corresponding mean values for AiryHeiskanen and VVM isostatic models become 250 ± 004 km and 216 ± 008 km respectively By assuming density contrasts of 05 g/cm2 and 035 g/cm3 for continental and oceanic regions respectively the VMM model yields the mean Moho depth 226 ± 01 km For this model the global rms difference to CRUST20 is 72 km while the corresponding difference between AiryHeiskanen model and CRUST20 is 11 km Also for regional studies Moho depths were estimated by selecting different density contrasts Therefore one conclusion from the study is that the global compensation by the VMM method significantly improves the agreement with the CRUST20 vs the local compensation model of AiryHeiskanen Also the last model cannot be correct in regions with ocean depth larger than 9 km eg outside Chile as it may yield negative Moho depths This problem does not occur with the VMM model A second conclusion is that a realistic variation of density contrast between continental and oceanic areas yields a better fit of the VMM model to CRUST20 The study suggests that the VMM model can primarily be used to densify the CRUST20 Moho model in many regions based on separate data by taking advantage of dense gravity dataFinally we have found also that the gravimetric terrain correction affects the determination of the Moho depth by less than 2 km in mean values for test regions approximately Hence for most practical applications of the VMM model the simple Bouguer gravity anomaly is sufficient
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