عنوان مقاله [English]
The earthquake of November 12, 2017 Mw=7.3 Sarpol-e-Zahab is located in western Iran and between the two faults of the Mountain Front (MFF) and the High Zagros (HZF) of the Zagros tectonic seismic zone, Which is related to the rupture of MFF fault in Sarpol-e-Zahab area.The focal mechanism of this earthquake has a reverse fault with a low slope (16 degree) to the northeast. Studies in this field indicate the existence of a maximum slip of about 5 meters at a depth of 18 km. Due to the earthquake on November 12, 2017, Mw=7.3 Sarpol-e-Zahab, surface displacements, especially very large landslide of Mela-Kabod and many aftershocks occurred in the form of scattered clusters in the region. The occurrence of aftershocks in clusters indicates the activity of small secondary faults. In the present study, the fault causing the main earthquake (Mountain Front Fault, (MFF)) was modeled using 3d-def three-dimensional boundary element code and the surface displacements, especially displacement due to the landslide of Mela-Kabod and also the location of secondary faults were extracted using average of maximum and minimum principal stresses as a criterion for determining the location of secondary faults. In order to validate the modeling results for the displacements, comparing the results with the data obtained from the Interferometric Synthetic Aperture Radar (InSAR) method and the combined offset tracking method, it was observed that The results of the two methods are almost close to each other and there are differences in the position of the displacements and the amplitude of their changes in the two methods, so that the amplitude of the displacements resulting from satellite data in the earthquake zone, It is -35 to 80 cm, while this range is -15 to 100 cm for the results of the modeling. Also, for the location of secondary faults, the average of maximum and minimum principal Stresses resulting from modeling are almost maximal in areas with aftershock density, especially in the southern part of the fault, and the depths with the most average of maximum and minimum principal stresses with depths that The aftershocks are high, except at a depth of 13 km, those are almost the same. In addition, to determine the sensitivity of the model to the input parameters, sensitivity analysis was performed, As a result, changes in dip angle and width of fault had the greatest effect on displacement output and also changes in Young modulus and length of fault had the greatest effect on average of maximum and minimum principal stresses output. The boundary element method used in this paper is one of the numerical modeling methods that has many applications in numerical simulation of fault dynamics, and its results have provided a broad view of the physics of earthquake rupture. Also, the compatibility of numerical modeling results with the results of radar interferometry (InSAR) and combined offset tracking in this paper shows that the boundary element method is a suitable method for numerical modeling of faults.
پژوهشگاه بینالمللی زلزلهشناسی و مهندسی زلزله، 7 آذر ماه 1396، گزارش مقدماتی زمینلرزه 21 آبان ماه 1396 سرپلذهاب استان کرمانشاه با بزرگای گشتاوری 3/7 (ویرایش چهارم)
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