Probabilistic seismic hazard mapping for Bangladesh using updated source models

Bangladesh, located near the Indian, Eurasian, and Burma tectonic plate boundaries, is highly susceptible to seismic hazards due to its complex tectonic setting. Despite identifying several tectonic features, their detailed characterization (e.g. slip type, slip rate, movement direction) remains unclear, leading to a lack of well-defined seismic source models and Ground Motion Prediction Equations (GMPEs) specific to the region to assess seismic hazards. This study addresses these limitations by updating areal source models (nine areal sources), estimating seismicity parameters such as mean seismicity rates, Gutenberg-Richter b-values, and maximum earthquake magnitude (Mmax), and utilizing comprehensive earthquake catalogs of historical and instrumental records. In the absence of region-specific GMPEs, a combination of equations (four different combinations) from similar tectonic settings was employed. Probabilistic seismic hazard analysis (PSHA) was performed for bedrock condition using R-CRISIS, producing maps of Peak Ground Acceleration (PGA) and Spectral Acceleration (SA) for 10% and 2% probabilities of exceedance in 50 years. Results reveal significant spatial variability, with higher seismic hazards along the eastern border, where maximum PGA values are 0.27 and 0.68 g for 10% and 2% exceedance probabilities, respectively. These findings provide critical insights for seismic risk assessment and inform resilience-building efforts in Bangladesh.