Research Projects

The north-eastward movement of the Indian plate and its interaction with the Eurasian plate in the north and Sunda plate in the east causes (interplate) deformation, giving rise to the Himalaya in the north and Indo-Burmese ranges and Andaman Sumatra island arc in the east. The deformation primarily occurs through the earthquake cycle and also because of erosion and other geological processes. Even within the plate interior regions, the Indian plate undergoes (intraplate) deformation causing earthquakes in the plate interior regions. Most earthquakes occur along the failed rift regions (e.g., the Kachchh, Narmada Son, and Godavari failed rift). However, a few occur along the unmapped fault zones, e.g., the 1989 Killari and the 1967 Koyna earthquake. The occurrence of these earthquakes causes damage to the property and loss of lives. Thus, for seismic hazard assessment, it is important to analyse the crustal deformation, understand the earthquake process in that particular tectonic unit, and identify the regions experiencing large deformation, which can host earthquakes in future. The analysis of crustal deformation can lead to the Strain and Seismic Hazard map which is more futuristic and based on physics of earthquake occurrence than the conventional seismic hazard zoning map which are based on past earthquake history on the known tectonic units. Global Navigation Satellite System (GNSS) measurements using several satellite constellations by various agencies, have been used to estimate crustal deformation at mm level precision. Besides, GNSS, space based InSAR analyses have also been used which give large spatial coverage but poor temporal coverage. To estimate deformation due to hydrological cycle, GRACE (Gravity Recovery and Climate Experiment) measurements have also been used, however they only offer coarse resolution (~300 km). Thus GNSS (mostly GPS) measurements with good spatial coverage have emerged as a very powerful tool to estimate temporal and spatial distribution of crustal deformation. Survey of India has now established more than 1200 GNSS stations across the country which are operating for more than 3-4 years. With additional data of ~1 year, these data will provide excellent constraints on intraplate and interplate deformation. It is proposed to use these, along with the already existing results on deformation rate through already established networks in a few regions, to make a Strain map of India, which will help in identifying the regions undergoing large deformation, the rate of deformation, and faults or tectonic domains/units that are experiencing deformation. Such a map would be evolutionary, as it would be updated continuously with more data from sites., etc. Clubbing it with the historical earthquake data, such a map can be used to approximately estimate recurrence interval of the earthquakes. Such a map will also be used to generate earthquake scenarios, thereby mitigating damage due to future large earthquakes.