Effect of Upper Mantle Density Structure on Moho Geometry

A constant value of the Moho density contrast is often assumed in the gravimetric methods used for determination of Moho geometry. This assumption might be sufficient in regional studies with a relatively homogenous lithospheric structure (and, consequently, small lateral variations in Moho density contrast). In global studies, however, this assumption is not reasonable, because not only the Moho depth but also the Moho density contrast vary substantially, and are, thus, likely to result in systematic errors in Moho geometry determined globally from gravity data. In this study we address this issue by investigating the effect of variable Moho density contrast on Moho geometry. We demonstrate that assumption of variable Moho density contrast (instead of a uniform model) substantially improves agreement between the global gravimetric and seismic Moho models by approximately 30 %.