Research Projects

The ~300 km long and ~50 km wide NW-SE trending Kopili Fault Zone, KFZ (Nandy, 1980) bifurcates Assam, the North Eastern state of India. This active intraplate KFZ, hosts several small to moderate earthquakes in Assam and the adjoining areas every year and has been remaining the source for several strong to major earthquakes (Kayal et al., 2012 & references therein) from past. Though the KFZ is a very crucial tectonic feature of Assam, there are not enough knowledge about the subsurface physical properties to get a better understanding of the stress release mechanism of the KFZ, as a few scientific activities (Barman et al., 2014; Bora and Biswas, 2019a, b; Bora et al., 2024; Kumar et al, 2016; Nandy, 1980; Sharma and Baruah, 2017; Sutar et al, 2017) have been carried out till date to characterize this fault. Apart from the tectonic activity, percolation of meteoric fluid into a fault zone also responsible for earthquake genesis (Gupta, et al. 2017). Normally, fluid under pressure, invades the critically stressed region, lowers the shear stress and thereby aid in the mechanical failure of brittle rock (Becken et al. 2011). The study of the last 50 years earthquake catalogue (available with National Center for Seismology, Delhi), as a part of preliminary study of this proposal, points out a vital information. It is observed from the study that most of the high magnitude earthquakes are occurred during the monsoon period (Jun to September) and few are occurred just pre and post monsoon period of Assam. Therefore, this observation points that apart from tectonic activity, fluid might also have role in earthquake generation in KFZ. On the other hand, focal mechanism solution of different earthquakes related to the KFZ (Sharma and Baruah, 2017; Bora et al., 2024) have shown strike-slip component, thrust with strike-slip component and normal with strike-slip component are associated with it, which signifies probable strain partitioning. However, scientific investigation regarding such observation is not available. Electrical resistivity, a physical parameter, has immense role in investigating the fluid associated with the subsurface rock matrix. Percolation of meteoric fluid to an active seismic region is also influence the deformation mechanisms and rheology of the surrounding rocks (Burgmann and Dresen 2008). Therefore, estimation of subsurface electrical resistivity in such situation is extremely necessary to examine such critical parameters. However, no electrical or electromagnetic geophysical investigation is available in KFZ to study these concerned topics. Magnetotelluric (MT), a passive electromagnetic geophysical technique, is capable of furnishing subsurface electrical structure from few tens of meter to several hundreds of kilometers. Therefore, an attempt has been made through this proposal to investigate the KFZ using MT to get a deeper insight into the tectonics, stress distribution, fluid interaction and strain partitioning (if any).