Gravity image generation over the Indian subcontinent using NGRI/EGM96 and ERS-1 altimeter data

A new technique for merging of land gravity using NGRI/EGM96 and ocean gravity using mainly ERS-1 altimeter-derived gravity data has been described. Methods for generation of residual/prospecting geoids and free-air gravity anomaly over Indian oceans surrounding Indian land mass using satellite altimeter data have already been developed. Recently Earth Gravity Model (EGM) 1996 data over the Indian land mass were available through Internet, It is, therefore, emphasized that a joint gravity image over the whole subcontinent, which includes land and ocean, will be of paramount importance for further studies in geophysical exploration/earth science studies in this region. Also, comparison of EGM96 data over certain profiles with satellite-derived information has shown the efficacy of the Satellite Gravity Method. Maps of gravity anomaly generated over the Indian subcontinent using ERS-1 altimeter/EGM96 data are presented along with their interpretation. A number of known megastructures over the study area, e,g, Bombay High, Saurastra Platform, 90 degrees East ridge over the oceans, etc. and Himalayan Thrust Belt, Narmada-Son Lineament, Saurastra Block, Dharwar Block and other major tectonic/structural features and their subsequent extension inside the sea could be successfully interpreted from these maps, Similar attempts have also been made with National Geophysical Research Institute (NGRI) generated gravity over land and altimetric/EGM generated gravity over oceans.