Estimation of probabilistic seismic hazard for Aizawl city in North Eastern India (NEI)

Abstract

It is common practice to describe seismic hazard in terms of Peak Ground Acceleration (PGA) and Spectral acceleration (Sa). Response spectrum representation of ground motion is directly applicable in structural response analysis. However, in India, engineers have been using a standard response spectral shape as recommended by the code IS-1893:2016 all over the country, modified only by a zonal factor representing the PGA of unknown probability of occurrence. This approach is silent about the various seismo-tectonic sources and non-uniform level of hazard at different parts of India. Thus, the expected or desired design life of structures cannot rationally harmonize with existing earthquake hazard and economical construction practices. Whereas, the underestimation of the hazard will lead to questionable safety margins, overestimation makes the projects uneconomical and hence social goal suffers in either case. It is in this context, Probabilistic Seismic Hazard Assessment (PSHA) that addresses engineering safety issues with quantifiable risk levels has become more popular. Now-a-days, seismic hazard maps are prepared in different countries for a given annual frequency of exceedance. With this in mind, probabilistic seismic hazard for Aizawl City has been prepared.In this study, we have estimated seismic hazard for different return period in Aizawl city. The active fault within 300 km radius of the city are considered for this study. The seismic hazard values estimated in this study will be useful for the structural designers of Aizawl city and its adjacent region to design various types of Engineering Structures.