Surface Consistent Seismic Hazard Assessment in the Shillong Plateau, Northeast India: A Probabilistic Approach Using Multiple Source Models and a Logic Tree Framework

ABSTRACT We perform probabilistic seismic hazard analysis (PSHA) in the Shillong Plateau by clubbing the up‐to‐date earthquake data and seismotectonic properties of the study area. Twenty‐one areal seismic sources are delineated based on the updated earthquake catalog, tectonic, and fault plane solutions. In addition to those 275 linear sources, including faults and lineaments, and point sources over 0.03°×0.03° grid are considered. The seismicity parameters of the sources are evaluated by the modified Gutenberg–Richter model and a non‐parametric Gaussian‐based estimator. Based on the efficacy test, three distinct most appropriate ground motion prediction equations are selected. The logic tree approach is applied to account epistemic uncertainty. Further, site effect is incorporated using V s 30 estimates from slope measurement of Digital Elevation Model. The PSHA of the Shillong Plateau at bedrock and surface levels has been computed in terms of peak ground acceleration (PGA) and spectral acceleration for spectral periods 0.0–3.0 s for 2%, and 10% probability of exceedance (PoE) in 50 years. PGA ranges from 0.47 to 0.78 g for 10% PoE in 50 years, and 0.89–1.78 g for 2% PoE in 50 years at the bedrock level, whereas it ranges from 0.43 to 1.10 g for 10% PoE in 50 years, and 0.90–1.97 g for 2% PoE in 50 years at the surface level. Hazard curves and uniform hazard response spectrum are prepared at the 11 district headquarters of Meghalaya state of India, providing critical inputs for the design of earthquake‐resistant structures. These results offer a robust framework for improving seismic resilience and regional safety in the Shillong Plateau.