# Seismic Risk in Alborz: Insights from Geological Moment Rate Estimation and Fault Activity Analysis
###### Abstract  
The Alborz mountain range in northern Iran is part of the active and seismic Alpide belt, where assessing seismic hazards is crucial due to the region's history of large instrumental earthquakes and destructive seismic background. Moment rate estimation, which quantifies tectonic activity, offers a novel approach to understanding the energy potential of active tectonic regions. In this study, a regional perspective is employed to investigate the maximum horizontal acceleration for Tehran, the major city in Alborz, resulting from the Sorkh-e Hesar and Ghasr-e-Furuzeh faults located approximately 7.5 km southeast of Tehran. These faults have a seismic potential of Mw 6.5 and a gravity of \(\sim\)0.5723. While previous studies have identified faults in northern Tehran as the greatest seismic risk, our findings suggest otherwise. The calculated geological moment was \(\mathrm{sp1360236}\)\(\mathrm{km}/\mathrm{y}\), with a seismic moment rate of \(\mathrm{1.83375}\)\(\times\)\(10^{14}\) Nm/y, providing valuable insights into fault activity and seismic potential in the study area.  
seismic hazards; seismic parameters; geological moment; seismic moment Alborz; Iran 2023 13 6236 233 233 233 233 233 233 2333 233 2333 233 233 233 233 233 233 233 233 233 233 233 2333 233 233 233 233 233 233 233 233 233 233 233 233 233  
Understanding the seismic hazards and risks in the Alborz region, including its major cities, is of paramount importance for earthquake risk mitigation and disaster preparedness efforts. By examining the seismic parameters and taking into account the complex interplay of various factors, such as fault mechanisms, fault density, and regional deformation patterns, we can improve our understanding of the seismicity of the region and make informed decisions for disaster planning, infrastructure development, and public safety measures. This study aims to contribute to this understanding by employing a regional perspective to investigate the maximum horizontal acceleration for Tehran, the capital of Iran, resulting from specific faults in the Alborz region, and provide valuable insights into fault activity and seismic potential in the study area. The geological moment rate is considered an aggregate of the crustal deformation, including the plastic and elastic components. Comparing seismic and geologic data helps to illustrate areas where all deformation rates are related to the crustal seismicity with some physical uncertainties [1; 2; 3; 4].  
Furthermore, it is possible to consider regions with high seismic deformation rates and interseismic slip across the faults [5; 6; 7; 8; 9]. Therefore, a joint effort to assess the number of large missing earthquakes is required to balance the moment released by seismicity [1; 2; 7]. In this study, we describe the calculation of geological moment rates from all active faults by presenting the relevant relations and the assumed values. We justify our preliminary selection of moment-rate models, describe the steps taken to constrain the seismicity rates to be consistent with observations, and provide the reasoning for not including seismicity rates from fault strain rates for the PGA map.