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Introduction During the development of plate tectonic theory, many scientists and researchers tried to use different methods to quantitatively and qualitatively express the amount and direction of crustal motion. In the basic theory of plate tectonics, plates are considered rigid blocks, which act as very effective stress conductors (Wilson, 1993). However, when we look closely at the behavior of the plate, we find that in many places (especially in the continental crust), deformation also occurs within the plate. So far, various relative and absolute methods have been proposed to determine the direction and direction of movement of tectonic plates. The velocity and direction of tectonic plates can be calculated by three methods: 1) Relative movement of pages, 2) Absolute motion and 3) Relative motion of spatial geodesic. Today, the relative velocity between two plates can be measured and calculated using the spatial geodesy method (Gordon and Stein, 1992). Before the 1980s, the only methods available for this type of survey were standard groundbased geodetic methods for measuring baselines using optical techniques or laser rangefinders, including geodoliths (Thatcher, 2003). These methods are accurate enough to measure the relative motion of the plates, which are a few millimetres per year. However, in the last three decades, measuring very long baselines using extraterrestrial methods through space technology has become possible. In this study, using the data of global models such as the global plate motion model (NUVEL1), international terrestrial reference frame (ITRF) and global strain rate model (GSRM), the direction and velocity maps of the crust in twelve points of Borazjan fault system that have fault plane solution data have been prepared. Accordingly, the direction of the current strain fields is compared with the results of the global models Nuvel1, ITRF and GSRM. Finally, the degree of conformity of the results obtained from the fault slip data and global models' results were compared to identify a more appropriate model for future studies. Methodology In this study, the states of direction and velocity of crustal movement in the Borazjan fault system have been studied using data from global models of tectonic plate motion. Therefore, using the data of global models of Nuvel1, ITRF and GSRM, the direction and velocity maps of the crust in the Borazjan fault system have been prepared. Furthermore, to compare the results of the above modelling with the current strain fields, the fault slip data obtained from the fault plane solution for twelve earthquakes in the Borazjan fault system have also been evaluated. Results and discussions There are four essential methods for overseas mapping: Very long baseline interferometry (VLBI), Satellite laser ranging (SLR), Global Positioning System and Doppler orbitography and radiopositioning integrated by satellite (DORIS). The VBLI method uses extraterrestrial radio signals or astronomers (Niell et al., 1979; Carter and Robertson, 1986). Satellite laser ranging (SLR) is calculated by measuring the travel time of a two-way pulsed laser light emitted from a satellite (Cohen and Smith, 1985). In the radio positioning method with satellite, radio interferometry related to satellites of Global Positioning System (GPS) is used (Dixon, 1991). This method is the most effective way to establish geodetic control over local and regional mapping (Kearey and vine, 2009). The DOIRS method is that a satellite examines the number of changes made in this frequency by sending several frequencies to the ground reference and returning this frequency from the ground reference to the satellite. The difference between the reciprocating frequencies is called the Doppler Effect. Mechanism of different global models for crust motion analysis, using different databases such as analysis of plate Euler points, satellite positioning system, laser distance detection with satellite, very long baseline interferometry, and terrestrial geodesy data. The data obtained from the earthquake slip vector and the data inside the well. Each global model uses one or a combination of the above data sets. The first model of this model is Nuvel1 (Global plate motion model) (Argus et al., 2011). This model later became the basis of other global models such as ITRF, GRSM, etc. (Altamimi et al., 2016; Prawirodirdjo and Bock, 2004). The mechanism of the Nuvel1 model is to analyze Euler points and determine the direction of the motion vector with ground geodetic models for 12 tectonic plates. The ITRF global model uses data from various intelligence services such as the International Geodetic Society Information Service, the International Reference Systems and Earth Rotation Service, and data such as very long baseline interferometry, satellite tracking, and The Global Positioning System has been modeling the motions of tectonic plates (Altamimi et al., 2007, 2011, 2016). The global GSRM model is a model that uses ground geodetic data to calculate the horizontal velocities and the horizontal strain of the earth's surface(Kreemer et al., 2018). The data of Nuvel1, ITRF and GSRM global crustal motion models in twelve points in the Borazjan fault system, which had seismic data with a magnitude of more than 5 Richter and fault plane solution, were extracted from reputable scientific sites. Then, directional maps and crustal movement rates in the Borazjan fault system were drawn using GIS software. The crust's direction and velocity of motion using Nuvel global model data show that the general plate movement direction has a northeast-southwest direction, and the rate of crustal motion in the northern parts is slower than in the eastern and southern parts. The resulting pattern shows that the velocity of crustal movement has increased from north to south and west to east. The directional map and rate of crustal motion using the ITRF global model data show that the general direction of plate motion is northeast-southwest, and the rate of crustal velocity increases from northwest to southeast. The direction map and crustal movement rate using the GSRM global model data indicate that the crustal movement direction is northeast-southwest, and the movement velocity rate in the southeastern parts is higher than other parts of the Borazjan fault system. Conclusion Nuvel1, ITRF, and GRSM global modelling in determining the direction of motion and crust velocity in the Borazjan fault system show that the pattern of crustal motion direction is not the same in these models. Also, these modelling results indicate different movement velocities for each model. The global modelling results indicate that the rate of crustal movement in the Borazjan fault system from the north and northwest to the south and southeast is increasing mode. Comparison of fault slip direction data in the Borazjan fault system with the ITRF, GSRM and Nuvel1 models reveals 58.3, 25 and 16.7 per cent similarity, respectively. Therefore, it can be concluded that the ITRF model has more adaptation to the slip direction in the Borazjan fault system than other models. [ABSTRACT FROM AUTHOR] |
