Paleoseismology of the Surgu and cardak faults-splays of the Eastern Anatolian Fault Zone, Turkiye

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 Turkiye trigger the westward escape of the Anatolian plate along these prominent structures. This study aims to reveal the earthquake history of the Surgu and cardak faults, which are important fault segments that splay from the EAFZ. In this context, overall, four paleoseismologic trenches were dug, two trenches on the Surgu Fault and two trenches on the cardak Fault. Along the Surgu 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 cardak 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 Surgu and cardak 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 Surgu and cardak faults have the potential to produce surface-rupturing earthquakes with an estimated magnitude of 7 or larger.