Probabilistic seismic hazard assessment studies for Mumbai region

The present study attempts to understand and assess the seismic hazard of Mumbai using probabilistic seismic hazard analysis (PSHA) with an updated catalogue of earthquake clubbed with recent knowledge on seismotectonics of the region. An updated catalogue of instrumental and pre-instrumental earthquake data within 300 km radius around the city has been compiled from different sources. The PSHA has been computed using two different seismic source models, viz., a fault (linear) and zone model (areal). A hybrid of five suitable ground motion prediction models (GMPM) consisting of widely accepted and latest GMPMs is used to compute the PSHA of Mumbai. The results obtained from different methodologies are integrated with logic tree approach to minimize the epistemic uncertainties in hazard calculation. Probabilistic seismic hazard maps in terms of peak ground accelerations (PGA) at bedrock levels for 2% and 10% probability of exceedance in 50 years are developed for Mumbai. Uniform hazard response spectrum (UHRS) on bedrock at eight different sites within Mumbai for spectral periods of 0.01—2 s is also computed. The low seismic hazard is observed and reasonably compared with the previous PSHA studies done for Mumbai region.