Observations from Geotechnical Arrays in Istanbul
Few small earthquakes with local magnitude slightly larger than ML = 4 were recorded by geotechnical downhole arrays that have been recently deployed in the west side of Istanbul. Same events were also recorded by Istanbul Rapid Response Network (IRRN) which comprises of 55 surface strong motion stations in the European side of Istanbul. The strongest one of these earthquakes took place on 12/3/2008 in Çınarcık with local magnitude of ML = 4.8. Even though the observed PGAs were not exceeding 0.01 g, an effort is made to model the recorded response at the downhole array sites as well as the at the IRRN stations using the acceleration records obtained by the deepest sensors, i.e. on the engineering bedrock, at the downhole array sites as input bedrock motions. 1D equivalent linear site response analysis that is generally adopted for site-specific response analysis is used for modelling. Observations from the recorded response and results from 1D modelling of ground response have yielded in general good agreement between the observed and recorded soil response at the station sites.
KeywordsGround Motion Peak Ground Acceleration Acceleration Time History North Anatolian Fault Ground Motion Parameter
Financial support for installation of downhole arrays are granted by the Turkish Scientific and Technological Research Council (TUBITAK), Istanbul Metropolitan Municipality, GFZ Potsdam and Boğaziçi University. The authors wish to acknowledge Prof. Mustafa Erdik, the coordinator of Istanbul Rapid Response Network, and Prof. Stefano Parolai, co-investigator at Megacity Istanbul Project. Barbaros Çetiner and Ahmet Korkmaz, members of project team for installing downhole arrays, are acknowledged for their tedious work in the field. The support of local municipalities of Bakırköy and Zeytinburnu as well as the personnel at Yunus Emre Cultural Centre and Fatih Mosque is greatly appreciated.
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