In our study, we conducted a comprehensive Probabilistic Seismic Hazard Analysis (PSHA) for Northeast India, which is one of the world's most seismically active regions. Our goal was to create a refined hazard model that improves upon the broad national zonation map.

To accomplish this, we first developed a homogenized and declustered earthquake catalog with a Magnitude of Completeness of 4.0. Using a novel hybrid method that combined data-driven clustering with the known tectonic framework, we delineated four primary seismic source zones. We then used a logic tree with region-specific ground motion models to account for scientific uncertainties.

In the study, it is found that the highest hazard is along the Indo-Burma ranges and the Kopili Fault Zone. Here, Peak Ground Acceleration (PGA) values exceed 0.35g for a 475-year return period. Critically for Guwahati, our analysis reveals that the primary threat comes from moderate earthquakes on nearby sources like the Kopili Fault rather than distant great earthquakes.