Study of high-resolution satellite geoid and gravity anomaly data over the Bay of Bengal

Abstract

Geoid and gravity anomalies derived from satellite altimetry are gradually gaining importance in marine geo-scientific investigations. Very high-resolution gravity database generated from Seasat, Geosat GM, ERS-1 and TOPEX/POSEIDON altimeters data of the northern Indian Ocean, has been used in the preparation of geoid and free-air gravity maps. In the present work, we have investigated various products of satellite data of the Bay of Bengal, thereby correlated to known plate tectonic feature (Sunda subduction zone), volcanic traces (Ninetyeast and 85°E ridges) and continental margin features. Besides, Swatch of No Ground and modified continental slope due to sediment discharge from East Coast rivers are some of the finer structures observed in free-air gravity anomaly data. Furthermore, the data are compared with ship-track gravity anomalies along 14.64°N lat. for their consistencies and interpreted under the constraints of seismic results for understanding the evolution of structural features of the region. Two different wavelength (100-200 and 200-500 km) components derived from satellite gravity anomaly data have been studied to explain the geophysicalanomalies associated with the Ninetyeast and 85° E ridges and two isolated structures in terms of isostatic compensation due to their loads with respect to the already evolved lithosphere. It is found that the magnitude of the flexure at crust-mantle boundary beneath the 85°E Ridge and structural high close to the margin is relatively higher than that of the Ninetyeast Ridge.