Slip rates and seismic potential on the East Anatolian Fault System using an improved GPS velocity field

Abstract

The East Anatolian Fault System (EAFS) is the second major fault system in Turkey, following the North Anatolian Fault System (NAFS). Unlike the NAFS, which produced 11 large earthquakes in the last ∼75 years, the EAFS has been relatively quiet during the same period of time. While historical records show that the EAFS has the potential to produce large earthquakes, the fault slip rates on the EAFS were not studied in detail, and were not quantified sufficiently. This is possibly due to the relatively low seismicity and slow slip-rates of the EAFS with respect to the NAFS. However, the determination of the slip rates of the EAFS is equally important in order to understand the kinematics of the Anatolian plate.In this study, we collected and analyzed new survey-type GPS data, and homogeneously combined published velocities from other studies, to form the most complete GPS data set covering the EAFS. In particular, continuous GPS observations were utilized for the first time to study the northern part of the EAFS. The results of the analysis give well-constrained slip rates of the northwestern segments of the EAFS, which is further connected to the Dead Sea Fault System (DSFS) in the south.The results show that while the slip rate of the EAFS is nearly constant (∼10mm/yr) to the north of Türkoğlu, it then decreases to 4.5mm/yr in the south. The slip rate on the northern part of the Dead Sea Fault System (DSFS) was also found to be 4.2±1.3mm/yr, consistent with earlier studies. The contraction rates along the EAFS are below 5mm/yr, except for the northernmost part near Karliova, where it reaches a maximum value of 6.3±1.0mm/yr. The results also show that two well-known seismic gaps across the EAFS, Palu-Sincik and Çelikhan-Türkoğlu segments, have slip deficits of 1.5m and 5.2m and have the potential to produce earthquakes with magnitudes of Mw7.4 and Mw7.7, respectively.