Gravity Inversion

Abstract

This chapter describes gravity inversionGravity inversion for various geophysical, geodeticGeodetic and geodynamic applications. After introducing some basic geophysical concepts and formulas for gravity inversion, various isostatic models and their use in determining crustal depthCrustal depth by gravity is described at length and compared and combined with seismic models of crustal depth. The preferred isostatic model is based on Vening Meinesz-Moritz hypothesis with a global isostatic compensationIsostatic compensation of Bouguer gravity disturbances rather than Bouguer gravity anomalies. There are also applications of gravity for estimating tectonic stressStress in the mantle and viscosityViscosity in the mantle (based on post-glacial land upliftLand uplift rate data in Fennoscandia). Temporal changes of the gravity field by many years of monthly repeated data from the satellite mission GRACEGRACE are used to demonstrate their power in determining large-scale Earth mass and geoid changes, such as positive geoid heightGeoid height rates in Laurentia and Fennoscandia related to glacial isostatic adjustments, and negative rates in Greenland and West Antarctica, as a result of mass losses due to ice-sheetIce sheet melting. Also, the upper mantleUpper mantle viscosity in Fennoscandia is determined by these data.