The tectonic map of India and contiguous areas

Abstract

The existing tectonic maps of India produced by the GSI and ONGC are largely based on the geological map of India combined with the topographic maps and the lineations evident in satellite pictures of the earth's surface. Broadly speaking, these consider only features observed on the surface of the earth. The third dimension is not much in evidence.The introduction of 3D-geophysical data into these maps ensured a substantial advance in the study of the crustal structure at depth. The new tectonic map is the result of this integration.Apart from India, the new map covers Pakistan, S. Tibet, Nepal, Myanmar, Sri Lanka, Maldives, the Arabian Sea, Bay of Bengal and the Andaman-Nicobar islands. Geophysical data used largely consists of gravity anomalies. To these are added information from limited magnetic and seismic measurements and topographic data. The result is a depiction of the subsurface as a number of crustal blocks of different orientations and dimensions fused together to form the Indian plate. This paper gives only a description of the results obtained by the analysis and does not bring into play the details of the data used in the analysis. Such an exercise is proposed to be carried out in a succeeding Memoir.

Overpressure zone under the Krishna–Godavari offshore basin: geophysical implications for natural hazard in deeper-water drilling

“…Gross tectonic features summarized on the figure illustrate three tectonic cross-trends to slope bathymetry and the Eocene shelf-edge at the margin of the Indian Shield. The latter mostly coincides with the continent-ocean boundary under KGOB (Balakrishnan et al 2009) India Map and Fig. 1(b) illustrates a summary tectonic map for KGOB, where three tectonic cross-trends to slope bathymetry and the Eocene shelf-edge at the margin of the Indian Shield, indicate tectonic complexities.…”

“…1(b) illustrates a summary tectonic map for KGOB, where three tectonic cross-trends to slope bathymetry and the Eocene shelf-edge at the margin of the Indian Shield, indicate tectonic complexities. The Eocene shelf-edge mostly coincides with the Continent-Ocean-Boundary under KGOB (Balakrishnan et al 2009). Tectonic complexities under KGOB represent the weak zones in upper crust; consequently, they act as potential locales for submarine natural hazard in offshore exploratory drilling and production.…”

Seismicity parameters for important urban agglomerations in India

“…This rift zone about 1600 km long in central India which separates northern and southern blocks of the Indian shield is a region of moderate seismic activity with infrequent earthquakes. Recently Balakrishnan et al (2009) based on three dimensional geophysical data located this hidden fault in the Bay of Bengal, as marked in Fig. 2.…”

Estimation of design basis earthquake using region-specific Mmax, for the NPP site at Kalpakkam, Tamil Nadu, India

“…In this context, the ECMI appears to be much more vulnerable compared to its counterpart on the west". Balakrishnan et al (2009) had generated a new tectonic map of India as the existing tectonic maps of India produced by the GSI and ONGC were largely based on the geological map of India combined with the topographic maps and the lineations evident in satellite pictures of the earth's surface. This new map considered a third dimension by introduction of 3D geophysical data by ensuring substantial advance in the study of the crystal structures in depth.…”

“…It can be noted here that F4 is Neotectonic Fault from SEISAT (2000) and also called as Palar Fault in Kalpakkam seismotectonic studies. Fault F1 is identified by Balakrishnan et al (2009) based on detailed geological studies carried out by Oil and Natural Gas Corporation Ltd. F6 is an active lineament marked in SEISAT (2000) in the Seismotectonic map of India. Fig.…”