Strong-motion and structural monitoring networks in Istanbul and their use for risk assessment

Abstract

Department of Earthquake Engineering of Kandilli Observatory and Earthquake Research Institute (KOERI) has installed and been operating for some time a large number of ground and structural seismic monitoring networks in Istanbul. The ground systems include 100-station Istanbul Rapid Response Network, 10-station Early Warning Network, and one 4-level downhole array. Installation of three more similar downhole arrays, and a small-aperture 72-channel dense array at the Air-Force Academy grounds are currently in progress. The structural systems include 27-channel real-time system at the St. Sophia Museum, 42-channel real-time system at Fatih Mosque, 15-channel real-time system at Fatih Sultan Mehmet Bridge (the 2nd Bosporus bridge), 24-channel triggered system at Suleymaniye Mosque, and 15-channel triggered systems at Kanyon Building (highrise office building), Isbank Tower (a high-rise office building), and ENRON Power Plant. Installation of more real-time structural monitoring networks are in progress or at planning stages, such as those for Sultanahmet (Blue Mosque), Bayezit, and Mihrimah Sultan Mosques, and the Marmaray Immersed Tube Tunnel under the Bosporus. The objective of the early warning ground network is to provide 5-7 s early warning of an earthquake, which can be used for automatic shutdown of some of the critical systems in Istanbul. The rapid response network provides the critical values of ground shaking (PGA, PGV, and spectral accelerations at 0.2 and 1.0 s) automatically within minutes of an earthquake, which are then transmitted to those agencies dealing with emergency response. Downhole arrays are located in the areas of Istanbul, where site amplification is expected to be critical. The objective in structural arrays is to monitor the health of the structure by continuously measuring its vibrations, and detect and locate damage after an extreme event, such as a large earthquake. A large component of structural monitoring activities is directed towards the research on developing new tools and techniques for system identification and damage detection. In addition to standard modal identification, more advanced real-time techniques are explored, such as wave the propagation approach and interferometric imaging. © Springer Science+Business Media B.V. 2011.