Evaluation of Earthquake Risk Parameters in the Historical Site of Istanbul Seda Kundak, Handan Dülger-Türkoğlu Department of Urban and Regional Planning, Faculty of Architecture, Istanbul Technical University, Taşkışla, 34437, Taksim, Istanbul, Turkey Seismic risk assessment requires data from different levels which present both hazard and vulnerability of a city or a region. Urban areas have complex structures to explore the inter-relationships of physical, social, demographic and economic features. Moreover, there is always a chain reaction among urban components which causes some difficulties to assess them. In large metropolitan areas, the urban pattern shows heterogeneity; hence, while calculating the earthquake risk levels of a city, it is vital to distinguish data indicators with the respect of zones’ properties. In the earlier research by Kundak earthquake risk parameters in Istanbul were produced and examined to reveal their loadings on relative risk levels [1]. Their findings point out that the parameters are able to explain the risk levels about 67.3%. The aim of this paper is to evaluate the seismic risk parameters in the historical part of the city which had been witnessed several medium and big sized earthquakes. The results illustrate that the risk parameters are corresponding to the seismic risk with an explanation level of 76.2%. Furthermore, the rank and the formation of the main factors are considerably different from which had been observed in city wide. The findings of this study and the comparison of findings with the former one, show that (1) the database selection is important to calculate the total risk, (2) beside macroscopic approaches, it is necessary to evaluate sub-regions of the city according to their features and (3) investigations on historical sites can help to validate the seismic risk estimations. Key Words: Risk assessment, Istanbul, Historical center, Vulnerability 1. Introduction Natural hazards can give great damages to urban areas according to their intensity and the vulnerability level of settlements. In general terms, the value of risk depends on the severity of hazard and the vulnerability of the elements which will be affected. The assessment of risk helps basically to reduce uncertainty; to point out the fields has to be prioritized and to make better decisions in management issues. Furthermore, risk assessment provides to estimate probable losses in human life, economy and infrastructure. In Istanbul, earthquake records extending two millennia indicate that, on average, at least one medium intensity (Io=VII-VIII) earthquake has affected the city every 50 years [2]. In the history, the earthquakes affecting Istanbul were compared according to their impacts on the old city, because, until the 1950’s Istanbul was more or less concentrated around the Historical Peninsula [3]. Today, with more than 10 million inhabitants, Istanbul is an earthquake prone metropolis which carries out the main economic, social and cultural activities of Turkey. On one hand, because of the existence of the North Anatolian Fault which is able to produce major earthquakes, and on the other hand because of the high vulnerability level of the city, Istanbul faces ARI The Bulletin of the İstanbul Technical University VOLUME 55, NUMBER 1