Updating The Earthquake Loss Estimation for Istanbul
EARTHQUAKE LOSS ESTIMATION FOR ISTANBUL
IN THE 20TH YEAR OF THE 1999 EARTHQUAKES
Since the study entitled “Earthquake Loss Estimation For Istanbul” that aimed to determine the earthquake impact on a city scale in 2009, the city has encountered significant urban transformation process. Istanbul is rapidly growing, changing and developing in terms of population, superstructure and infrastructure. 30% of the building stock in the city now, consist of relatively new structures constructed after 2000. The urban transformation projects continue rapidly. Mass housing extends within the empty spaces in the city or its perimeters, a vast number of high rise buildings with over 20 floors have been or are being built. Various significant projects (Yavuz Sultan Selim Bridge and it’s access roads, Marmaray, Eurasia Tunnel, new metro lines) have been completed and became part of city’s infrastructure. In addition to all the changes in infrastructure and superstructure, new scientific studies have been conducted and new information and findings were revealed within the last 10 years on seismic hazard of Istanbul. All of these developments reveal the need to update the earthquake loss estimation across the Istanbul city in general.
Within the scope of Memorandum of Understanding entitled “Updating The Probable Earthquake Loss Estimation in Istanbul” signed between Bogazici University and Istanbul Metropolitan Municipality (I.M.M.), the current population, building and infrastructure inventory of Istanbul was generated, city scale earthquake risk assessment studies were concluded using up to date seismic ground motion data/models. Studies were carried out by the Earthquake Engineering Department of Kandilli Observatory and Earthquake Research Institute, with collaboration from I.M.M. Department of Earthquake Risk Management and Urban Improvement, Directorate of Earthquake and Geotechnical Investigation. Seismic hazard analysis, risk analysis of the elements of urban superstructure and infrastructure and earthquake risk assessment of Yenikapı and Maltepe meeting spaces have been performed as part of the project. While deterministic and probabilistic methods were used for urban seismic hazard and risk analyses, various vibration measurements and modelling approaches were used and liquefaction potantial and stone pitching stabilization analysis were performed for earthquake risk assessment of meeting spaces. Through the earthquake risk analysis performed with use of ELER and ELER-Lifelines software, 15 different earthquake scenarios were obtained from a Mw=7,5 scenario earthquake and ground motion simulation, and also assessments were realized aimed at probable damages in buildings and infrastructure and consequent life loss and casualties as a result of probabilistic earthquake ground motion distribution corresponding to 72, 475, 2475 years return periods, within the boundary of Istanbul Metropolitan Municipality.
In the 20th year of Kocaeli and Düzce earthquakes, it is of great importance to take the results obtained using updated superstructure and infrastructure inventory in the light of latest earthquake hazard information and models, into consideration; and make use of them in planning studies towards any municipal functions, planning for disaster response, structural rehabilitation against earthquakes and prioritization of the regions for urban transformation. Project results are also used as a basic input for “Megacity Indicators System for Disaster Risk Management – MegaİST” project that is being carried out by Directorate of Earthquake and Geotechnical Investigation of I.M.M., and within this context, disaster risk is assessed in a holistic way; as social vulnerability is also taken into consideration besides physical vulnerability, and analyses are performed together with coping capacity analysis, and managerial and organizational efficiency analysis of the risk management process.