Uysal, I. Tonguç; Karabacak, Volkan; Aykut, Tunahan; Ring, Uwe; Liu, Entao; Sancar, Taylan; Leonard, Nicole; Tong, Kui; Todd, Andrew J.; Temel, Abidin

The North Anatolian Fault (NAF), one of the most prominent plate boundary continental fault systems on Earth, facilitates the westward movement of the Anatolian microplate into the Aegean region. The temporal and spatial evolution of the NAF is important for understanding the mechanism of escape tectonics during plate interaction in active orogenic regions. The driving force(s) behind the movement of the NAF and the time period over which this occurred remain controversial. Our U–Pb and K–Ar dating of syntectonic minerals shows that a predecessor faulting initiated as early as ~40 Ma due to shortening along the Neo-Tethyan suture zone. Fault reactivations occurred at ~20 and 10 Ma synchronously in eastern and western Anatolia, suggesting that the NAF already existed by ~20 Ma. Our data also show that the westward motion of Anatolia was not only controlled by the Arabia–Eurasia collision in eastern Anatolia, but also by Aegean extension.

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Karabacak, Volkan; Sancar, Taylan; Selcuk, Azad Saglam; Buyukdeniz, Yusuf

This article presents the results of the first paleoseismological studies conducted along the Ulubat Fault and their inferences on the earthquake behavior of the south branch of the North Anatolian Fault Zone (NAFZ). The Ulubat Fault is divided into 3 segments according to its geometric characteristics and paleoseismological behavior. Along the fault segments, at least 6 paleoearthquake event have been distinguished in the last 16 thousand years with paleoseismolgic fault excavations. The dating results correlated with the historical records show that the latest surface ruptures along the Ulubat Fault occurred with the earthquakes of <161/170 AD (I=IX), 1143 AD (M=6.0) and 1855 AD (M=7.3), respectively, and migrated to the west. Although it does not provide sufficient statistical evaluation opportunity, the paleoseismological data presented in this study proves that the segments of the NAFZ south branch do not present characteristic earthquake behavior in terms of recurrence period and this irregularity may be due to the multi-fragment geometry of the fault zone in the region.

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Selcuk, Azad Saglam; Erturac, Mehmet Korhan; Karabacak, Volkan; Sancar, Taylan; Kul, Ahmet Ozkan; Yavuz, Mehmet Ali

Sancak-Uzunpazar Fault Zone is N40E-trending sinistral shear zone that has a 50 km length and 5 km width between Karakocan (Elazığ) in southwest and Kaynarpınar (Bingöl) in northeast. The fault extends parallelly to East Anatolian Fault is bounded by the North Anatolian Fault to the northeast and Karakoçan Fault to the southeast. Herein, morphological features, the tectonic setting of the Sancak-Uzunpazar Fault Zone and the first paleoseismological studies on it is represented. The Sancak-Uzunpazar Fault Zone is consist of two parallel segments (called East and West) with a 1.5 km distance. Conducted field studies and aerial photogrometry show that the segments exhibit morphological features like faceted surfaces, faulted scarps, shutter ridges, and offset streams. Especially, average offsets are about 7-12 m along the eastern segment while the cumulative maximum offset reaches 1.1 km. Moreover, revealed paleoseismological data show evidence of at least two surface ruptures during Holocene. Obtained morphological data reveal that the Sancak-Uzunpazar Fault Zone may have a relatively lower slip rate when compared to other active faults in the region and the reflection of the slip rate to the morphology is more evident in the eastern segment.

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