from inversion of magnetic anomalies

Inversion of magnetic data was carried out on 40 profiles collected across the continental margin of Visakhapatnam at a spacing of about 10 km and magnetic basement map for this region is prepared. The map reveals complex anomalies par-ticularly beneath the inner shelf with amplitudes reaching as high as 1800 nT. These anomalies appear to be associated with the complex basement structure reported earlier. The significant features inferred include, (a) a shallow and highly faulted basement, in the inner shelf; (b) a NE-SW ridge-trough configuration in the mid shelf; (c) NW-SE trending basement up-ward off Bhimunipatnam to Kalingapatnam and (d) N-S trending shallow basement trend off Chilka lake. Curray et al.1 presented a detailed study of the structure, tectonics and geological history of the northeastern Indian Ocean. During 1985-87 geophysical studies were carried out mainly related to the near shore structure and tectonics of the eastern continental shelf2-9. In earlier studies Murthy et al.6 analysed the magnetic and bathymetry data of this offshore region up to about 150 km seaward, extending from Paradi