Assessment of seismic hazard including equivalent-linear soil response analysis for Dhaka Metropolitan Region, Bangladesh

Dhaka is one of the most populated cities in the world, which means that the occurrence of natural hazards will put the city in a critical situation. A seismic hazard analysis (SHA) is a prerequisite to reduce the risk of an earthquake event in Dhaka. This paper, focusing on the active faults of Bangladesh and the soil condition, represents the calculation of the peak ground acceleration (PGA), spectral acceleration (SA), and amplification factor. The analysis here used an updated seismic catalog (up to 2020), three source models (linear, areal, and smoothed seismicity), and eight attenuation models (selected by ranking techniques). Data from drillings are used to build the soil model, and one-dimensional frequency-domain equivalent-linear analysis is applied to calculate the amplification factor and the acceleration on the surface. The results show that the PGA changes from 0.14 to 0.19 and from 0.33 to 0.46 on bedrock for a return period of 475 and 2475 years, respectively. The worst-case scenario for Dhaka is the movement of the Jamuna Fault (Madhapur section), which can cause a PGA from 0.08 to 0.68 on bedrock. The results also suggest that the soil can amplify the acceleration up to 2.4 times. PGA on the surface for the return period of 475 years varies from 0.18 to 0.41. The design spectra and zonation maps are presented in the paper.