بررسی فعالیت‌های نئوزمین‌ساختی با استفاده از شاخص‌های ژئومورفیک و توان لرزه‌خیزی گسل‌ها (حوضه آبخیز خیاوچای)

Abstract
Introduction
Faults are one of the important tectonic elements that, by cutting the earth's crust into pieces and moving the crust pieces vertically and horizontally, in addition to causing earthquakes, directly participate in the creation of primary landforms, which are the primary structural forms for the action of dynamic factors and the creation of secondary forms. On the other hand, faults along their length create weak points in the earth's crust and thus create the necessary conditions for magmatism, salt diapirism, hot springs, etc. Faults can also be involved in the creation of some meanders, rapids, deviations, captivity of waterways, as well as the formation of lakes and wetlands. Geomorphological tectonics is the study of landforms caused by tectonism and the interaction between tectonics and geomorphic processes {11}. Almost no region in the world can be found that has not been affected by neotectonic changes during the last few thousand years {21}. Geomorphic indices have been widely used as a tool for identifying and characterizing parts deformed by active faults {12}. The goal of geomorphometry is to extract the shape features of the earth's surface and its complications using digital models of the earth's surface and parameterization software. Quantitative measurement of landforms allows geomorphologists to investigate the role of active tectonics in changing landscapes by measuring geomorphological indicators in different landforms {22}. In the simplest form, landforms and shapes that make up the earth are characterized by size, height, slope. In other words, numerical measurements allow geomorphologists to objectively and concretely compare and evaluate different shapes, and by calculating patterns and indices, they can recognize and explain the geomorphological differences and similarities of a certain area from another area {2}. New studies have been conducted inside and outside of Iran, which are mentioned below.{24 and 25}, investigated active tectonic assessment in Hableroud and Kurdan basins based on geomorphic indicators. These researchers came to the conclusion that Kurdan basin is in class 1 and Hableroud basin is in class 2. According to the classification of tectonic index (IAT), it can be said that both regions are tectonically active, but the amount of tectonic activity in the Kurdan basin is higher than in the Hableroud basin. {27}, evaluated the active tectonics of the Sirvan river basin using geomorphic indices, and they came to the conclusion that the results of this index indicate that among the studied sub-basins, the Shuisheh sub-basin with an average of class 2 has a more active condition than the other sub-basins. Is. {28}, in order to evaluate the active tectonics in the area of Idia Eska in the southwestern part of Cameroon using geomorphic indicators. The results of the work of these researchers showed that the reactivation of the faults located in this area are the cause of severe earthquakes. {10}, they studied the tectonic and geomorphological activities in the San Lucas region in the Central Cordillera using morphological and geomorphological indicators. They came to the conclusion that the most tectonic activity is related to the slopes of Mount Simiti, north of the Simiti San Blas faults, in line with the faults trending northwest-southeast and in the north of Palestine basin. {26,38, 19, 14, 16, 4). The aim of the current research is to evaluate and analyze the neotectonic activities and seismic power of faults using geomorphic indicators (case study: Khiauchai watershed).
Methodology
The present research has been carried out to investigate and analyze the assessment of the relative amount of land-building activity using zoomorphic indicators in Khiauchai watershed. In the first stage, to perform the calculations related to each index and to compare the results obtained from the index calculations, the studied area was divided into sub-basins. By using Archydro plugin in GIS10.3 software and DEM 12 meters elevation digital model, sub-basins, main waterway networks were extracted and the studied area was divided into 15 sub-basins. Then, in the next step, the indices were calculated. In the next step, using 1.100000 geological maps of geological organization and mineral discoveries in the study area, the main structures of the region such as faults were determined. All main faults and minor faults located in the area were identified. In the final stage, the results of measuring the geomorphological indicators and the main structures of the region were studied and analyzed. The indicators studied in the region are: Relative prominence index (Bh), drainage density index (Dd), shape factor index (Pf), integral and hypsometric curve index (Hi), river longitudinal gradient index (SL), valley floor width to height index (Vf), ratio index The width of the valley to the height of the valley (V) is the index of the ratio of the shape of the drainage basin (BS).
Conclusion
According to the evaluation of neotectonic activity using the geomorphic indicators of the Khiauchai watershed, it was concluded that the region is in a high neogeological state in terms of tectonic activities. Finally, based on the shape factor index, the most neotectonic activity is related to sub-basins 3 and 14. The most neotectonic activity based on drainage density index is related to sub-basins 11 and 12. Also, sub-basin 14 has the highest value in the salience index in terms of neotectonic activity. Longitudinal gradient index of sub-basins 14 and 12, integral index of sub-basin 4, valley floor width index of sub-basins 8, 10 have the most neotectonic activities. The index of the ratio of valley width to the height of the sub-basin is 10, and in the ratio of the shape of the sub-basin, 8 is the most neotectonic activity. Therefore, it can be concluded that based on the index of relative tectonic activity, the largest area of Khiauchai basin is in the category of medium and high tectonic activity. Based on the evaluation of the seismic power, this result was obtained: Zare has a magnitude of 4.41, Noorozi and Ashjai have a magnitude of 5.76 and Noorozi has a magnitude of 1.71. Therefore, it is suggested to prevent human and financial damages caused by neotectonic activities on the fault, preventive activities should be carried out to prevent unauthorized constructions on the studied faults.
Keywords: survey," neogeological activity," geomorphic indicators," fault," Khiauchai basin".