NW Iran-SE Turkey is a tectonically active zone related to the Arabia-Eurasia convergence, but the active stress state in this zone has not yet been clearly studied. To improve the knowledge of present-day stress state in this region, optimum reduced stress tensor was analysed. For this, a large number of earthquake focal mechanisms (277) were collected. The analyses show most mechanisms exhibit strike-slip to thrust faulting. These data indicate that this region is dominated by an N158° maximum horizontal compressive stress (SHmax) belonging to a transpressional tectonic regime. | Turkish Journal of Earth Sciences Turkish J Earth Sci 2021 30 235-246 http earth TÜBİTAK Research Article doi yer-2011-18 Active tectonic stress field analysis in NW Iran-SE Turkey using earthquake focal mechanism data Ahad NOURI MOKHOORI1 Behnam RAHIMI1 Mohsen MOAYYED2 1 Department of Geology Faculty of Sciences Ferdowsi University of Mashhad Mashhad Iran 2 Department of Geology Faculty of Natural Sciences University of Tabriz Tabriz Iran Received Accepted Published Online Final Version Abstract NW Iran-SE Turkey is a tectonically active zone related to the Arabia-Eurasia convergence but the active stress state in this zone has not yet been clearly studied. To improve the knowledge of present-day stress state in this region optimum reduced stress ten- sor was analysed. For this a large number of earthquake focal mechanisms 277 were collected. The analyses show most mechanisms exhibit strike-slip to thrust faulting. These data indicate that this region is dominated by an N158 maximum horizontal compressive stress SHmax belonging to a transpressional tectonic regime. In the scale of the study area the relative magnitude of the intermediate and minimum principal stress axes do not differ much ϕ . Brittle deformation in this area is dominantly accommodated by a combination of strike-slip and thrust faulting Aϕ to . The analyses reveal that two sets of faults show a high tendency to slip and reactivate. These sets contain NW-SE-striking right-lateral and NNE-SSW-striking left-lateral faults. The results of this study may help to study the active seismicity tectonic activity and seismic risk in this region. Key words Stress inversion stress regime focal mechanism solution active tectonic NW Iran-SE Turkey 1. Introduction Okada 2018 iii explaining faulting pattern in different In recent decades present-day crustal stress state has been areas of a region Simpson 1997 and iv evaluating slip .
