Tectonics of the eastern continental margin of india

1. Introduction 1

Passive (Divergent) Continental Margins 2 Active (Convergent) Continental Margins 3 Transform Margins 4 Characteristics of Passive Margins 4 Exploration of Passive Margins 7 Origin of the Indian Ocean and the Bengal Fan 8 Evolution of the Eastern and Western Continental

Margins of India 11 Seismo-Tectonics of the Indian Subcontinent 13 Peninsular or Stable Continental Region Seismicity 15 Importance of Studies on Passive Margins 18 The Eastern Continental Margin of India (ECMI):

A Case Study 18

2. Evolution of the ECMI 19

Introduction 19 Qualitative Analysis of Geophysical Maps 21 Structural Lineaments from Magnetic Data 28 Support from Gravity Data 40 Summary of Structural Lineaments over the ECMI 42 Two-Stage Evolution of the ECMI 43 Link-up with Gondwanaland Break-up 51 Some Ambiguities in the Proposed Theories on the Evolution 56

3. Tectonics of Offshore Basins 65

Introduction 65 Cauvery Offshore Basin 65 Pre-Cambrian Mega Lineaments of Cauvery Basin 71 Krishna–Godavari Offshore Basin 76 Land–Ocean Tectonic Signatures of the Krishna–

Godavari Basin 84 Mahanadi Offshore Basin 87

4. Hazards Associated with the ECMI 103

Introduction 103 Puducherry Shelf, Tamil Nadu Coast 104 Mahabalipuram–Palar shelf, Tamil Nadu Coast 108 Ongole Shelf, Andhra Coast 112 Kakinada and Kalingapatnam Shelf, Andhra Coast 116 Summary on the Seismic Hazard over the ECMI 124

5. Conclusions 131

Evolution of the ECMI 132 Tectonics of Offshore Basins 134 Seismic Hazards over the ECMI 137