The last devastating earthquake on 17 August 1999 (İzmit earthquake) ruptured part of the northern branch of the North-Anatolian Fault Zone (NAFZ) and caused substantial damage in some areas of the city of İstanbul, although the epicentre was roughly 90 km east of the city (Özel et al., 2002, Bull. Seism. Soc. Am.). The authors report approximately 1000 people killed in the collapse of buildings, mainly in the suburb of Avcılar, which is located even 20 km further west than the city proper. The damage pattern as well as the analysis of aftershocks done by the authors clearly showed that local site effects must have played a substantial role apart from inappropriate building stock.
The Earthquake Master Plan for Istanbul (Boğaziçi University, Istanbul Technical University, Middle East Technical University & Yildiz Technical University) already anticipates that local geology will affect the expected damage pattern caused by a future event. Therefore, based on our experience gained during the DFNK-project (German Network Natural Disasters, http://www.dfnk.de/ ) we aim at analysing site effects as well as including them into the modelling of ground motion scenarios. The latter results will be relevant for engineers (sub-project 3) and requires not only appropriate software, but also detailed knowledge on the distribution of physical parameters in the subsurface and on the probable rupture extension and mechanism (sub-project 1).