Investigating the aftershocks and Coulomb stress change of the 2017 Ezgeleh earthquake with a moment magnitude of 7.3, West of Iran


1 Department of Geology, Faculty of Science, Golestan University, Iran

2 Road, Housing and Urban Development Research Center, Tehran, Iran.


The Ezgeleh earthquake (Mw: 7.3) occurred in November 2017 in the north-western Sarpole-Zahab city of Kermanshah, followed by many aftershocks. This research used the Coulomb stress change method to investigate the correlation between spatial distribution of aftershocks and stress change patterns. The basis of this method is that an earthquake can change the stress field of nearby areas and may affect the occurrence of subsequent earthquakes. The aftershock distribution pattern may be evaluated from the Coulomb stress change maps and profiles, which are calculated using the mainshock's location, magnitude, focal mechanism and, depth, and the rupture's length and width. Based on The seismicity map, the distribution of the aftershocks of the Ezgeleh earthquake is heterogeneous and concentrated in several dense clusters with different trends. Due to the thrust mechanism of the mainshock and thrust and strike-slip mechanisms aftershocks, the Coulomb stress changes were calculated based on two types of receiver faults: specified and optimal strike-slip and thrust geometries. The density map of aftershocks was also drawn to check the results. The results show that the best correlation between the distribution pattern of aftershocks and Coulomb stress changes maps and profiles is observed for the case of the optimal strike-slip receiver fault. In this map, the pattern of the stress-increased areas are remarkably similar to the areas of increased density of aftershocks (aftershock clusters) with two north-south and east-west trends. The diversity in the trends and mechanism of faults in the region may cause heterogeneity in the distribution pattern of aftershocks.


Main Subjects

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