Since its inception, the CSIR-National Geophysical Research Institute (CSIR-NGRI) has seen its Gravity and Magnetic Group make significant strides in understanding geodynamic processes and exploring natural resources. The Gravity Map of India (2006) is the Group's flagship product, prepared in collaboration with several other national organisations (GSI, ONGC, Survey of India, OIL). The Group is well-equipped with the latest instruments for temporal and static variation measurements for Gravity and magnetic fields.

Theoretical developments have concentrated on the use of spectral decay and scaling spectral method to determine the depth of the causative sources located at different depths, removal of considerable wave length isostatic regional anomalies based on zero Free-air anomaly, regional-residual separation based on finite element method, designed long digital filter operators using Hankel transform, modified centroid method for estimation of Curie depth that uses magnetic data, and the structural mapping of major geological and tectonic domains using enhanced potential field gradient functions. We drove high-resolution gravity data for offshore regions by processing raw altimetry data. We has also conducted extensive G-M studies for mineral exploration in central and south India.The Group has carried out significant work over the Infra Cambrian petroleum system of the Bikaner-Nagaur Basin for shallow gas exploration and in the Krishna-Godavari Basin, South Rewa Basin, etc., under the integrated geophysical exploration program.

The Group collected dense Gravity and magnetic data in Saurashtra (15000 points), Kutch (3500 points), Deccan Syneclise in Central India (10,000 points), Cauvery Basin, Tamil Nadu (6700 points) at an interval of ~2 km. Integrated modelling delineated the 3D configuration of the subtrappean Mesozoic sediments present at a depth range of 0.5-3 km, followed by the basement. The study also delineates several high-density intrusive bodies in the basement at an average depth of about 4-7 km that best fits the residual gravity anomaly of the study area.

The recent 2D and 3D lithospheric density modelling in SGT and Eastern Indian shields have delineated the Lithosphere-Asthenosphere Boundary at about 130-140 km depth. The thinned lithosphere provides compelling evidence of lithospheric modification in the above two regions due to prolonged thermal perturbation and/or stretching during the Gondwana breakup.

The study of temporal changes in Gravity related to changes in the mass balance of the Earth has led to research in deformation and seismo-genesis on the one hand and hydrological changes on the other. As recorded by the GRACE satellite mission, temporal changes in Earth's gravity field in Northern India reveal a steady, large-scale mass loss that we attribute to excessive groundwater extraction. Combining the GRACE data with hydrological models to remove natural variability, we conclude that the region lost groundwater at 54 ± 9 km3/yr (2002-2008), probably the most enormous groundwater loss rate in any comparable-sized region on Earth. This trend, if sustained, will lead to a significant water crisis in this region when this non-renewable resource is exhausted.

The Group's present focus is:

• Mineral exploration using G-M methods

• Mapping of Geothermal fields

• Integrated Geophysical modelling for crustal and lithospheric studies

• Developing the new algorithms for G-M data inversion (2d/3d)

• Application of machine learning in Potential fields

• Study of Dynamic triggering in the Indian region

• Modelling of satellite gravity field for mass re-distribution and hydro-geodesy