Seismotectonic Investigation of Karliova Triple Junction (KTJ) and the Surrounding Area : Eastern Turkey

Eastern Turkey is the most tectonically active region in Turkey. This region contains the East Anatolian Fault Zone (EAFZ) that is one of the most active tectonic zone and it has a long history of devastating earthquakes. At the same time EAFZ is the southeastern boundary of the Anatolian Block. EAFZ is a left-lateral strike-slip fault that extends between Karliova and Hazar Lake, in Eastern Turkey. The Karliova region is located between North-Anatolian Fault Zone (NAFZ) and EAFZ, and it shows high seismicity due to the active fault systems. The Karliova triple Junction (KTJ) where the NAFZ intersects the EAFZ is the most tectonically active region in Turkey. We do not have enough information about the seismic and seismotectonic features of the KTJ region. The lack of dense instrumental network have created difficulties in delineation of seismic sources. Previous scientific studies have suggested that the Yedisu Segment is a seismic gap, but it has not been characterized by detail studies. The Kandilli Observatory and Earthquake Research Institute (KOERI) has increased the number of the seismic stations in the region since 2005. We are in the process of installing 7 more broad band (BB) seismic stations at the Karliova junction region where the two major fault zones intersect. Thus, the physical caharacteristics of the earthquake sources will be better characterized and their relations with the very complex active fault network in the region will be investigated in detail. Particularly, by analyzing focal mechanisms/MT solutions of the earthquakes with a magnitude of M>4.5, the deformation characteristics, earthquake occurrence patterns and the seismic gaps of the region will be revealed. Our study will include: The ongoing active deformation will be monitored in real-time, Different fault segment properties and their geometries will be characterized,Fault plane- MT solutions-Source parameters will be obtained,Monitoring of foreschock-afterschock activities of future earthquakes will be accomplished, Regional stress analysis will be done, Monitoring of seismic gaps in the region will be carried out, Velocity structure and crustal properties of the region will be determined by seismic tomography. Particularly, after 2003 a significant earthquake activity has been observed in the region. A total of 13 earthquakes with magnitudes of M≥5.5 occurred between 1992-2011 in the region. These are: January 27, 2003 Pulumur (Erzincan)Earthquake (Mw=6.1); May 01, 2003 Bingol Earthquake(Mw=6.4; 2004 Askale (Erzurum) Earthquakes (M=5.6); August 11, 2004 Sivrice (Elazig) Earthquake (M=5.7); 2005 Karliova (Bingol) Earthquake Series (M=5.8-5.6); 2007 Sivrice (Elazig) Earthquake Series (M=5.5-5.2); March 08, 2010 Basyurt-Karakocan (Elazig) Earthquake (M=6.0) and June 23, 2011 Icme (Elazig) Earthquake (M=5.7) occured in the region. This study was supported by Bogazici University Research Projects Commission under SRP/BAP project No. 6040.