Site response studies for seismic hazard analysis of Kolkata city

Seismic microzonation for urban areas is the first step towards a seismic risk analysis and mitigation strategy. It is essential to obtain a proper understanding of the local subsurface conditions and to evaluate the ground shaking effects for the predicted earthquake. This paper presents a methodology to study the effects of local soil conditions on the propagation of seismic motion parameters for sites where no prior earthquake data is available. The methodology uses equivalent linear method for site response analysis and wavelet-based spectrum compatibility approach to generate synthetic earthquake motions. The Megacity of Kolkata (located between 22.6° N and 88.4° E), in India has been considered to explain the methodology. Typical results are presented. The results indicate the amplification of ground motion in the range of 4.46 to 4.82 with the fundamental period ranging from 0.81 to 1.17 s. Further, the maximum spectral accelerations vary in the range of 0.777 to 0.947 g