A fast method to compute the gravity component due to density contrasts in the subsurface and to estimate the terrain density

We show how a very simple gravity data processing, suitable to be performed even during the gravity survey, can lead to a sort of pseudo-Bouguer anomalies successful in highlighting the effects of the main density contrasts in the subsurface. By a linear regression analysis, our processing separates free-air anomalies into two components, namely terrain-correlated anomalies (TCA) and terrain-uncorrelated anomalies (TUCA). We show that TUCA assumes a shape similar to standard Bouguer anomalies. However, this component is independent of the terrain density. Finally, the TCA, when used in a linear regression with the unit-density gravity effect of the topography, allows estimation of the average terrain density.