Tectonic geomorphology of the Şemdinli Yüksekova Fault Zone (ŞYFZ) and Başkale Fault Zone (BFZ) (SE Turkey): Evidence from morphometric analysis and neotectonic structures

The collision between the Arabian and Eurasian plates resulted in the uplift of The East Anatolian Province of Shortening (EAPS). Within the EAPS, the faulting mechanism is characterized by right- and left-lateral strike-slip faults, thrust faults, and a relatively limited occurrence of normal faults. When examined on a regional tectonic scale, about 70% of the deformation of the EAPS is controlled by strike-slip faults. However, the proportion of right- and left-lateral strike-slip faults contributing to this deformation remains unknown and is poorly understood. Two adjacent fault zones located at the southeastern margin of EAPS were selected to investigate the deformation associated with right- and left-lateral strike-slip mechanisms using morphometric analysis along with field observations. These fault zones are the Şemdinli Yüksekova Fault Zone (ŞYFZ), which exhibits right lateral deformation and is defined as a seismic gap, and the Başkale Fault Zone (BFZ), which has a left lateral deformation and that caused a destructive earthquake in (23/02/2020, Mw: 5.9). To elucidate the relative degree of active tectonics of both fault zones, morphometric analysesis were applied alongside field surveys. An adaptation of the relative active tectonic Index (Iat) was computed for Başkale and Yüksekova-Şemdinli sub-basins in the region. The results supported by field observations indicate that the drainage basins are largely controlled by fault activity and exhibit a youthful topographic character. Moreover, quantitative data derived from the Index of Active Tectonics (IAT) reveal that the ŞYFZ demonstrates very high tectonic activity, while the BFZ displays moderate levels of active tectonic deformation. These numerical findings, which indicate ongoing deformation, are further corroborated by field observations that clearly reflect the surface expressions of tectonic activity.