A PGA amplification study for Varanasi city (India): Implications for seismic hazard assessment

The Indo-Gangetic Plain is one of the most densely populated regions of the world, and the seismo-tectonics of the Himalaya has a profound impact on the seismic hazards on this area.We analysed various seismic and lithological parameters of one of the oldest and most densely populated cities of the Indo-Gangetic Plain, called Varanasi, to assess the seismic risk for the city.This study revealed that the surface geology of this region has a considerable impact on the Peak Ground Acceleration (PGA), which determines the degree of damage in any area after an earthquake.The various factors, such as the population density, thickness of sediment, and building structure pattern of the city, make it highly vulnerable to seismic hazards.In view of this, we have used multiple data sets to assess the seismic amplification for the city.Our results suggest that the surface geology of the area may amplify the signal from 1.7 to 3.2 times in the study area.Thus, the seismic hazard of the area is higher than the expected hazard for seismic zone III.