Paleoseismology of the Sürgü and Çardak faults—splays of the Eastern Anatolian Fault Zone, Türkiye

The sinistral East Anatolian Fault Zone (EAFZ) and the dextral North Anatolian Fault Zone (NAFZ) are two important strike-slip faults that delimit the boundaries of the Anatolian plate. The north-south directed compressional forces in eastern Türkiye trigger the westward escape of the Anatolian plate along these prominent structures. This study aims to reveal the earthquake history of the Sürgü and Çardak faults, which are important fault segments that splay from the EAFZ. In this context, overall, four paleoseismologic trenches were dug, two trenches on the Sürgü Fault and two trenches on the Çardak Fault. Along the Sürgü Fault, at least two paleoearthquake events have been determined on the trench walls, one event occurred around 3400 BCE and the second event happened between 2085 ± 65 BCE and 790 ± 20 BCE. Moreover, trenching results from the Çardak Fault indicate two surface rupturing paleoearthquakes between 10520 ± 95 BCE and 5780 ± 65 BCE, and between 3215 ± 125 BCE and 825 ± 55 CE, respectively. The focal mechanisms of important instrumental earthquakes around the Sürgü and Çardak faults on the EAFZ show that NNE-SSW trending compressional forces are actively dominating the tectonic setting of the region in the contemporary era. Paleoseismological investigations suggested that the Sürgü and Çardak faults have the potential to produce surface-rupturing earthquakes with an estimated magnitude of 7 or larger.