New insights into the North Tabriz Fault from the analysis of third order stresses

Abstract

The North Tabriz Fault (NTF) is a major regional fault traversing northwestern Iran. It persists through the Turkish-Iranian plateau crossing the central part of the Iranian-Azerbaijan region. This fault has paleo-seismological history, and has been responsible for many devastating earthquakes, which in historical times have destroyed the city of Tabriz at least twelve times. The NTF is a WNW–ESE trending strike-slip fault but also includes a thrusting component that runs for more than 100 km between the Khoy-Siyah Cheshme- Gaylato fault and the Zanjan fault systems. In this research, seismicity, remote sensing, and field data available for the NTF are studied. Specifically, the stress phases for the three main segments of this fault (Northern, Middle, and Southeast) are analyzed and their hazard potential is established. Numerous horsetail structures, generated by compression resulting from dextral offset movements along the faults, exist in the Misho and Shibly mountain ranges. The phases of the stress relating to the NTF segments are analyzed by the direct inversion stress-separation (Angelier method). That analysis, together with fault movement potential analysis, reveals that the southeast segment of the NTF has the highest potential to generate displacement, suggesting that this fault segment poses the highest risk for future large-scale earthquakes. Moreover, analysis of recent seismicity along the fault, including major earthquake events of 2023 in Southeast Turkey identify a gap in seismicity along part of the NTF, suggesting that future earthquakes should be expected in that region.