Spatial and temporal variation of seismic b-values across the West Tehran

Abstract

Until now, numerous efforts have been made to find earthquake precursors. One of the factors that can predict the occurrence of future earthquakes is a decrease in the b-value parameter. In this study, for the metropolis of Tehran, with a population of over 8 million, located on or near many active faults, it is estimated that if the maximum seismic potential of these faults happened again, the greatest disaster in human history would occur. In this case, the analyses indicate a minimum of several hundred thousand casualties and sometimes more than a million. In the current study, various faults around Tehran were investigated, and given that the faults on Tehran have not had serious seismic activity for over a thousand years, this article focused exclusively on adjacent faults, particularly the Eshtehard faults. Therefore, in the current study, the seismicity and tectonics of western Tehran were investigated by analyzing seismic parameters using earthquake data collected from 2003 to 2023. In general, the investigation of the temporal changes in the study area showed that the b-value decreased before the December 20, 2017, earthquake and an increasing trend afterward. Observing anomalies in the b-value before and after the main movement in the area shows that changes in this parameter can be considered a precursor for estimating the time and location of earthquakes. Therefore, a useful step can be taken toward knowing the local seismic hazards by using earthquake data recorded by seismic networks and continuously monitoring the changes in the b-value.