Deformation and movement of Qom, Alborz and Kushk-e Nosrat fault zones in the northern part of Qom

The placement of the Iranian crust at the junction of the Arabian, Indian and Eurasian plates has caused tectonic disruption. The creation of numerous faults and many folds along with seismicity in the Iranian crust are signs of this disruption. The continental basin of northern Qom is located in central Iran. The general trend of the important faults in this area includes Qom, Alborz and Kushk-e Nosrat faults, is northwest-southeast. This faults with a length of more than 50 km affected by Arab-Eurasian plate convergence, and have played an important role in seismicity and deformation of Qom area.Morphological evidence and the existence of numerous fault fragments that have cut Quaternary sediments indicate the activity of these structures around the city of Qom. Despite the valuable studies that have been done on the faults of Qom, Alborz and Kushk-e Nosrat, still there are ambiguous opinions and ambiguities about how these faults move and their seismic potential. Qom fault with a length of more than 50 km, has a northwest-southeast trend that continues from the mountains southeast of Qom to the south of Zefreh in the northeast of Isfahan. During this fault, Oligo-Miocene limestone and marl are driven on Quaternary sediments. Alborz fault also has a northwest-southeast trend with a dip to the southwest that has cut the northern limb of the Alborz anticline. Alborz fault has also driven Oligo-Miocene units on Quaternary units. Kushk-e Nosrat fault is part of the fault system. It starts from the southeast of Hoz-e Soltan Lake and continues to the Avaj fault. The general direction of Kushk-e Nosrat fault is 280 to 290 degrees and in most cases, it has a dip more than 80 degrees to the south. One of the objectives of this study is to identify how these faults displacement and activity.One of the methods of tectonic assessment is the use of geometric indices. Among these, according to the lithological characteristics and the location and distribution of the basins, the indices of Vf, hypsometry and SL have been selected and the results have been analyzed. Results of morphometric indices with fault geometry and stress orientation data, have been able to elucidate some tectonic features of the area. Morphometric studies show the areas around Saveh fault and Kushk-e Nosrat fault in the northern part of Saveh as well as areas in the south of Qom have the potential to rise. Other zones do not have significant uplift.The geometry of the faults and orientation of the maximum compressive stress show that the maximum compressive stress direction is N30 to N330 and according to the direction of the fault, the fault mechanism is estimated to be Dextral. The stress inferred from the seismic event of 2007/06/18 also confirms the right-lateral shear motion along with the reverse motion in the faults.The low vertical uplifts does not indicate the absence of activities, but can indicate the compressive and shear components or the specific deformation of Central Iran. This type of movement can be easily interpreted by knowing stress orientation. The shear-compressive deformation of the Qom area is due to the northeastern movement of the Arabian plate and the limitation due to the Caspian hard crust. Undoubtedly, the Qom is an area that different seismic researchers has been considered and studies with different views and study styles. Comparing the results of these studies has helped to discover the Unknown activity zone.In general, the northern part of Qom is an area with high seismicity that the mechanism of earthquakes is mostly strike-slip with thrust. Therefore, moderate to large earthquakes are expected to occur in the future.