SEISMIC MICROZONATION OF KOLKATA

Abstract

This dissertation report presents the deterministic seismic microzonation of densely populated. Kolkata city situated on the world's largest delta island with, very soft and thick soil deposit in the surficial layers. A fourth order accurate staggered-grid finite-difference algorithm for SH-wave propagation simulation in visco-elastic medium is used for the linear computation of ground motion amplifications. The scenario of simulated amplification factors in the different frequency bands revealed that the Kolkata city is very much prone to severe damage even during a moderate earthquake. Further, very selective damage may occur at some of the localities during local and distant earthquakes. The deterministically predicted PGA at bedrock level is o.0844g and maximum PGA predicted at free surface is o.6g in Kolkata city due to maximum credible earthquake (MCE) associated with Eocene Hinge Zone (EHZ) at a depth of 36 km. Different maps such as fundamental frequency (F0), amplification at F0, average amplification in the considered frequency bandwidth (0.25-1Hz, 1.0-2.0 Hz, 2.0-5.0 Hz 5.0-10.0 Hz and 0.25-10.0 Hz), peak ground acceleration (PGA), peak ground velocity (PGV) and peak ground displacement (PGD) and factor of safety against liquefaction at 3m, 6m and 9m level are developed for variety of end-users communities, including structural and geotechnical engineers building officials, emergency managers, land-use planners, private businesses, and the general public