Gravity anomalies, interpretation

Abstract

Due to new interpretation techniques and increased computer power, most of the computational problems related to the forward and inverse gravity modeling, which caused big problems even recently, are solved. For example, the direct computations using Equation 2 may be performed for on large grids taking into account 3D density variations. Also a principal difference from the early-stage period is that the interpretation of the gravity anomalies is performed now in combination with other methods. The most profitable results are obtained from the integrative interpretation of the gravity and seismic data. Further combination with geothermal data provides the possibility to separate the effects of temperature and composition variations within the Earth. The obtained density models are used in various applications. This information is essential for a geodynamic modeling that results in determination of the mantle flows, tectonic forces moving the lithosphere blocks, and stress distribution in the crust and mantle at both regional and global levels. Interpretation of the gravity anomalies is also widely used in geophysical prospecting. In some situations the seismic investigations fail to give results, for example, when a high velocity layer masks the underlying low-velocity layers. Here the gravity and magnetic investigations are the principal means to obtain information on the underlying structure. Two principal problems should be a key issue for the gravity modeling in future. As it was shown, reliability of the gravity modeling depends on additional data used in the interpretation. Therefore, it is necessary to bring together data from various disciplines, which might be used in construction of integrative interpretation models. Geophysicists just started approaching this ultimate goal. The second principal issue is improvement of the technique for integrative interpretation. In particularly, special attention should be paid to solution of nonlinear inverse problems and to ultrahigh dimension problems.