Determination of building age for Istanbul buildings to be used for the earthquake damage analysis according to structural codes by using aerial and satellite images in GIS

Istanbul is located in one of the most active seismic zones in the world. Since Istanbul is the industrial, commercial, cultural and educational center of Turkey, it attracts ongoing migration from all over Turkey. However, those migrations caused unplanned construction and those unplanned constructions led to the formation of vulnerable and undocumented building stock in Istanbul. Many scientific studies estimated that Istanbul is expecting a major earthquake and the expected damage to the structures will be extensive. Therefore, there have been a lot of building damage estimations for the possible Istanbul earthquake to recommended precautions and to be prepared. A major disadvantage of Istanbul case is the lack of knowledge for the absolute number of buildings and the ages of those buildings. Up to now, many studies for Istanbul used the building dataset of Istanbul with the number starting from 1.1 to 1.5 million without the absolute age information. To make a correct or reliable earthquake damage estimation, a building database that contains at least building age, construction type and number of floors is required in most of the earthquake loss assessment software. This paper aims to determine the buildings of Istanbul and the age of them, according to structural codes for the earthquake zones by using aerial and satellite images of Istanbul. The classification should be based on the regulation so as to minimize the age classes and maximize the accuracy. First building regulations in Turkey came into force in 1940 in order to determine essential conditions for the realization of functional, safe and disaster-resistant building design in Turkey. Last updated building code regulations have come into force in 2007 in Turkey. It was also important to investigate the proper building detection method for the aim of this study, and it was determined as the manual digitization. In this study, the buildings of Istanbul and the age of them are determined for every single building, by digitizing the selected aerial and satellite images of Istanbul based on the official structural codes in Turkey. Thus, first the exact number and location of buildings in Istanbul and every single buildings age were determined. The results were also validated with two separate studies of Istanbul for different periods of times. By this way, earthquake damage analysis for the Istanbul buildings can be run for the real building data of Istanbul with any earthquake loss assessment software.