Paleo and modern stress regimes of central North Tabriz fault, Eastern Azerbaijan Province, NW Iran

The North Tabriz fault is a segmented dextral fault in Northwest Iran, with a history of major destructive earthquakes that have repeatedly destroyed the city of Tabriz (current population 1.6 million). The quiescence of the fault (last major temblor in 1854) and a lack of outcrop study have hampered stress analysis. Resolution of the stress states on the fault could be used for seismotectonic study along the North Tabriz fault and for understanding the geodynamics of the Arabia-Eurasia collision zone. Using fault-slip data collected from 88 localities in the fault system, we conducted an inversion analysis of this fault-slip data and analysis of the stratigraphic, geometric, and structural information. As a result, we confirmed that transcurrent deformation is prevalent on the North Tabriz fault and adjacent areas and is generally accomplished by predominant NW-SE-trending dextral and NE-SW-trending sinistral faults. Specifically, three separate tectonic episodes are recognised from the stress inversion data, consistent with the geologic data: (ⅰ) a post-Cretaceous and pre-Early Miocene compressional (Laramian) stress regime, (ⅱ) an Early Miocene extensional stress regime, and (ⅲ) modern tectonic episode with different local stress regimes (compressional and extensional) along the different segments of this fault.