Investigation of Site Characterization and Vulnerability in Antakya (Turkey) under Basin Effect

Abstract

It is very important and necessary to know the depth of the bedrock in determining the soil behavior. However, determining the depth of bedrock spatially is a very difficult and costly process. The depth of the bedrock can be obtained by using the dominant vibration frequency obtained by the microtremor data. The bedrock depth map was created with the correlation produced from the dominant vibration frequencies obtained from microtremor measurements made in Antakya (Turkey). In bedrock calculations at low frequencies, the value range shows scattering. In the vulnerability analysis for Antakya soils, a low level of vulnerability (Kg = 6) was obtained in the east and northeast of the area. It has been observed that the S-wave velocity (Vs) in this area is lower than 406 ms-1. In this case, this value has been accepted as the vulnerability threshold value in Antakya soils. Peak Ground Acceleration (PGA) and Peak Ground Velocity (PGV) were obtained for each location by using earthquake ground motion levels with 2%, 10%, 50%, and 68% probability of exceedance in 50-year periods. The PGA values in the region range from 0.43 to 0.47 g for earthquakes with a return period of 475 years.