Seismotectonics of Peninsular India and Sri Lanka

Abstract

Peninsular India constitutes one of the prominent and largest Precambrian shield areas of the world. It is exposed to the south of the Indo Gangetic Alluvial Plains (IGAP); in other words the IGAP is separating the Himalayas to the north and the peninsular India to the south. The Shillong Plateau in the northeast constitutes an outpost separated from the main shield by the Bengal basin (Bangladesh Plain), and from the Himalaya by the Brahmaputra river (Fig. 7.1). While the Himalaya is a region of dominant compressional tectonics and the IGAP is a region of relatively less eventful recent sedimentation, the peninsular India, in contrast, is a region marked by early Archaean cratonisation with associated Proterozoic belts. The Indian peninsular is known as a stable cratonic subcontinent. It was reported that the seismicity of peninsular India is low (Chandra, 1977), despite its ongoing collision with central Asia (Tapponnier et al., 1986). During the last decade (1993–2003), however, three strong/large earthquakes (M 6.0≈7.7) occurred in peninsular India (Fig. 7.2).