Active Tectonics and Seismic Hazard Assessment of Kermanshah Region (West of Iran) by Probabilistic Method: A Case Study

The Kermanshah region is located in the north‒western foothills of the Zagros Mountains in Iran. The reason for selecting this region is the occurrence of significant earthquakes, such as the Ezgeleh earthquake, which was unexpected and unusual for the Zagros region. For this reason, the area from Tazeh Abad of Salas-e Babajani to Qasr-e Shirin settlements was chosen for peak acceleration assessment and hazard analysis. This area has encompassed the large earthquakes of recent years within the region. To analyse the seismic hazard in this area, a probabilistic approach, historical earthquake catalogues and instrumental seismic data from 1900 to 2023 years was utilized. Foreshocks and aftershocks were removed from the catalogue of earthquakes. A map of earthquakes with magnitude M > 4 and faults of the region were delineated, and four seismic sources were identified in the area from Tazeh Abad to Qasr-e Shirin settlements, and their zoning digital elevation model was created. Subsequently, by estimating the parameters of each source, including a-value and b-value, the acceleration resulting from the activity of the sources was probabilistically estimated for a return period of 475 years. The maximum ground acceleration for a return period of 475 years was calculated to be 0.36 Gal. Also, the hazard analysis of the study area was conducted and seismic behaviour of this region, as a part of the Zagros Orogenic Belt, shows intense compression and uplift.