The significant Mw 6.1 Kopili Fault earthquake that struck on April 28, 2021, profoundly impacted causing substantial structural damage, ground cracks, liquefaction, provides an important instance to examine seismic processes in the Kopili Fault region. Considering an integrated approach, the study aims to quantify ground deformation, hydrological changes, seismicity and strong ground motion parameters, to evaluate its implications for regional seismic hazard. DInSAR analysis indicates no significant coseismic ground deformation in the epicentral region, with a mean deformation of about -0.71 \(\pm\) 9.71mm while NDWI analysis indicate increase in humid surface from 0.41% to 0.62% in Missamari area characterized by liquefaction, suggesting the development of new pits signifying subsidence. Intense seismic activity, observed from database of 6336 events during 1964 to 2022, highlight clusters of aftershocks, suggesting continued stress transfer and fault reactivation mainly at depth of 10-30km. Evidently, the event is characterised by intersection of Kopili Fault to the HFT in lower Himalaya imparting stress to the rupture area of the fault. Stress tensor inversion of fault plane solutions indicates NNE directed principal stress, reflecting the prevailing stress conditions of the Kopili valley, aligned with regional pattern. Notably, accelerograms recorded at five SMA stations showed high shaking in the epicentral region, by strong site-to-site variability influenced by local geology and basin effects identifying stiff rock at Agia and Tura; and softer rock at Jorhat, Guwahati and Golaghat. Detail analysis of ground motion parameters portray peak ground acceleration during the main event is highest at Guwahati (0.05g), indicating MMI IV shaking intensity. The parameters investigated under this study contribute to a better understanding of the regional tectonics and fault behaviour, providing valuable insights into the consequences of the 2021 earthquake and its implications for future events.
