Abstract:
Over the course of history, Marmara region in northwestern Turkey has been the site of numerous destructive earthquakes. Based on historical and instrumental earthquake records, the Marmara sea region is one of the most seismically active regions of the Eastern Mediterranean. The Marmara region is under the influence of the western part of the North Anatolian Fault Zone and the N-S extensional regime of Western Turkey. Therefore, the earthquake risk analysis is very important for the MARMARAY Project. The 76-km-long MARMARAY Project is an important project not only for Turkey but also for the world because it joins the two continents through railway. It will also serve for a comfortable and healthy way of environment, providing a contemporary solution for urban transportation. In this paper, using average wave velocities in layers, thickness, density and formation data based on the PS logs, and seven different boring logs located in different geological regions with depth range 43-60 m from the ground surface, ground response functions have been obtained. The influences of nonlinearity on the site response analysis have been summarized and evaluated with a numerical example. Based on the soil profiles transferred to nonlinear earthquake site response analyses of layered soil deposits (NERA) software, the rock and soil records of August 17, 1999 Kocaeli earthquake from a recording site in Bes, iktas, town of Istanbul, response and design spectrums that may be considered crucial in case of an earthquake have been obtained. The acceleration record having a PGA value of 0.04287 g in east-west component has been used as an input motion to sublayers (i.e., sand, gravel, clay) with constant damping ratio of 5 %, using NERA program. The study also provides a critical overview of the site response analysis of the field under interest.
