Role of Transferred Static Stress Due to Sarpol-e Zahab Earthquake in Aftershock Distribution

Document Type : Seismology and Engineering Seismology




By using slip model from USGS and focal mechanism and aftershocks distribution from Iranian Seismological Center (IRSC) for Sarpol-e Zahab earthquake (Mw 7.3) on November 12, 2017, we investigated the correlation between Coulomb stress changes and aftershocks distribution. In this study, about 500 aftershocks with magnitude larger than 2.5 and azimuthal gap less than 180 degrees were selected. Calculated Coulomb stress changes on the optimally oriented faults showed that most of the seismicity occurred in regions of increased stress and the majority of them concentrated on the ruptured plane, especially in west and south parts. Besides, nodal planes of the selected 11 aftershocks received positive Coulomb stress changes. Therefore, there is a good correlation between Coulomb stress changes and aftershocks distribution in Sarpol-e Zahab event. Furthermore, calculated static stress on the surrounding faults showed that middle part of the High Zagros Fault (HZF), the northern part of the Main Recent Fault (MRF), and the northern part of the Zagros Foredeep Fault (ZFF) are located in the positive stress change area.


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