Relevance of hot underlying asthenosphere to the occurrence of Latur earthquake and Indian peninsular shield seismicity

The cause of the highly destructive Latur earthquake of September 30, 1993, which occurred below the flood basaltic region of the Indian peninsular shield killing more than 10,000 people, is still not well understood despite several geoscientific investigations carried out after the main event. In the present work, we have examined in detail multiparametric geophysical data to understand its origin in particular and the seismicity of the Indian shield in general. Our study suggests that the Indian peninsular region is characterised by large variation in asthenospheric depths from 31 km to 186 km, depending on tectonic segments. The unusual seismic activity thus appears to stem from hot and upwarped underlying asthenosphere, which causes continuous build-up of localised stresses due to differential isothermal rise, and large lateral temperature differences on a regional scale beneath the highly fragmented Indian shield. The shield appears to be undergoing large scale rejuvenation and has become much more unstable than other global shields.