Fault mechanisms and their frequencies during destructive earthquakes in Iran

Iran has been affected by the convergence of the Arabian and Eurasia plates. For this reason, it has experienced destructive earthquakes throughout history. In terms of tectonic and seismic properties, Iran can be divided into 5 general seismotectonic provinces; Zagros, Central-East Iran, Alborz-Azerbaijan, Makran, and Kopeh Dagh. One of the facts that best describes the characteristics of earthquakes is their focal mechanism. In this article, the focal mechanisms of these 5 provinces were collected and classified with FMC software. For each zone, the frequency percentage of each group of faults was determined. Most faults are in the reverse class or compression type with the strike-slip component. Most of the faults of the reverse type are related to Zagros province, which includes 58% of its earthquakes and 42% of Iran's earthquakes. Thus, it seems the Zagros has been more affected by the convergence of the Eurasian and Arabian plates than other regions. Normal faults in all provinces have a small frequency so that only about 3% of the total earthquakes in Iran are in this class.