Iranian Journal of Geophysics

Iranian Journal of Geophysics

Analysis of temporal variations in seismicity and Its relationship with major earthquakes in the Kermanshah region (2013-2018)

Document Type : Research Article

Authors
Davood Kazemi Lafmejani 1
Elham Shabani 2
1 Ph.D. Student,Tehran North Branch, Islamic Azad University, Tehran, Iran
2 Associate Professor,Department of Seismology, Institute of Geophysics, University of Tehran, Tehran, Iran
10.30499/ijg.2025.504637.1669
Abstract
The Kermanshah region in western Iran is a part of the Zagros seismic belt, which has experienced intense tectonic activity due to the collision of the Arabian and Eurasian plates, leading to significant earthquakes such as the 2017 Sarpol-e Zahab earthquake (MN 7.3) and the 2018 Ezgeleh earthquake (MN 6.4). This region is characterized by its complex geological structure and high seismic hazard, making it a critical area for studying earthquake precursors and tectonic processes. In this study, we examined changes in seismicity of Kermanshah from 2013 to before the 2018 earthquake to analyze pre-seismic processes and indicators of ground preparation for major earthquakes. Current earthquake prediction research emphasizes the need for reliable early warnings. However, the main challenge is not determining the certainty of an event but understanding the tools that seismology provides for earthquake prediction. Past efforts in this field, driven by evolving advancements and needs, have been organized into various branches, including statistical seismology, geodetic monitoring, and laboratory experiments on rock mechanics. Gradually, moving beyond traditional definitions, a broader understanding of earthquakes has emerged, incorporating multidisciplinary approaches to better comprehend the physical processes leading to seismic events. Identifying pre-seismic phase changes in seismic zones is now considered a key factor in earthquake prediction, as stress changes are directly linked to seismicity. This study aims to track and analyze pre-seismic phase changes, particularly in relation to the 2013 (MN 5.6), 2017 (MN 7.3), and 2018 (MN 6.4) earthquakes, using ETAS (Epidemic-Type Aftershock Sequence) and ZMAP models to evaluate seismic data from the Kermanshah region. The data was collected from the Iranian Seismological Center (IRSC), which provides a comprehensive catalog of seismic events in the region. The Kermanshah region, with its history of significant earthquakes occurring in short time intervals and within a small geographical area, provides an ideal setting for testing theories related to pre-seismic phases, such as seismic quiescence and reverse earthquakes. These phenomena are critical for understanding how stress accumulates and releases in the Earth's crust. Evidence of both seismic quiescence and reverse earthquakes was observed in this study. According to the results, we propose that before the 2017 and 2018 earthquakes, the seismic epicenters were surrounded by areas of seismic quiescence, where a noticeable decrease in seismic activity was detected. These findings are aligned with previous research, which has also documented similar patterns in other seismically active regions. They support the hypothesis of regional stress reduction due to pre-seismic slip or aseismic movement at plate boundaries. This stress reduction may explain the decrease in seismicity prior to major earthquakes, as the crust undergoes a phase of stress redistribution before a significant rupture occurs. The study highlights the importance of continuous monitoring and advanced modeling techniques to better understand the complex processes leading to large earthquakes. By integrating these findings into earthquake forecasting models, it may be possible to improve early warning systems and mitigate the risks associated with seismic events in tectonically active regions like Kermanshah.
Keywords
The ETAS model, seismicity, seismic quiescence, seismic reversal, Sarpol-e Zahab

Subjects

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Iranian Journal of Geophysics
Volume 19, Issue 4
September and October 2025
Pages 155-173