Microzonation of earthquake hazard in Greater Delhi area

Abstract

A spate of earthquakes in the recent past, causing extensive damage,has heightened the sensitivity of engineers and planners to the looming seismic risk in densely populated Indian cities. Delhi city is in a seismically active region and hence it is important to understand the existing earthquake hazard to the city on a scientific basis. This article, after discussing the seismo-tectonic status of the city and its environs, presents probabilistic seismic hazard analysis of an area of 30 km x 40 km with its centre at India Gate, Delhi city. The quantified hazard in terms of the rock level peak ground acceleration value is mapped on a grid size of 1 km x 1 km, for a return period of 2500 years. In engineering parlance, this corresponds to a probability of exceedance of 2% in a design life of 50 years. This map can be used as the basis for further site-specific studies at soft, soil deposits.