List of Articles Seismicity

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  1 - Seismotectonics of the west of Golestan province, the east of south Caspian region
  Maryam Agh-Atabai Marjan Tourani
  Golestan province is located in one of the seismically active zones of Iran. The seismicity maps of Golestan province show that density of earthquakes in the west is more than the east. In this research, the parameters including b-value, recurrence time and seismic mome More

  Golestan province is located in one of the seismically active zones of Iran. The seismicity maps of Golestan province show that density of earthquakes in the west is more than the east. In this research, the parameters including b-value, recurrence time and seismic moment were studied to investigate the seismicity of the west of Golestan province. The focal mechanism of earthuqakes and field data were used to determine the stress orientations in the study area. The estimated b-value is obtained as 1.24±0.2 which is comparable with the Alborz. Since the northern and southern parts of the study area have different geomorphological and structural characteristics, some of these parameters were calculated for two subdivisions; Dasht-e-Gorgan in the north and foothill in the south. Results of this study show that the earthquakes in the Dasht-e-Gorgan compared to the foothill are smaller with shorter recurrence times. For the foothills, the calculated P-axes using the stress tensor inversion method is found to be subhorizontal with trend N-NNE. For this region, at least two trends, N and NW, is calculated using field data. This result show the change of stress directions during the structural evolution of this area. The calculated p-axes trend for the Dasht-e-Gorgan is NE. In both studied areas, the focal mechanisms of greater earthquakes are consistent with the E-W to NE-SW trend of main faults especially the Khazar fault. But, the smaller events in the Gorgan Plain show a different trend and mechanism. Comparison of these two subdivisions shows that the northern Alborz foothill is more dangerous than the plain. Manuscript profile
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  2 - Segmentation of Shotori fault using structural, geomorphology, seismicity and fractaly analysis
       
  Shotori active fault zone (in the northern end of Nayband fault) has a dextral strike-slip mechanism with a revers component. Landsat image studies show that this fault is uncontinuous and segmented. In this research, based on fault geometric discontinuity, two segments More

  Shotori active fault zone (in the northern end of Nayband fault) has a dextral strike-slip mechanism with a revers component. Landsat image studies show that this fault is uncontinuous and segmented. In this research, based on fault geometric discontinuity, two segments, were determined on both the northern (with trend of N40w) and southern segments (with trend of N20w). Both of them are reverse with a right lateral slip movement component. The southern segment is the most active segment, based on fractal earthquake and fractal fractures (Ds= 1/60, DN=1/73) and earthquakes (Ds=0/43, DN=0/68) morphotectonic¬ parameters such as river slope indicator (SLs=1703/27,SLN=1526/7), sinuosity river channel (SS=1/24,SN=1/27), the V ratio (Vs=0/7,VN=0/9) and structural and seismic data. The most frequent recorded earthquakes and the biggest registered earthquake with a magnitude of 7.4 on the Richter scale have taken place in the southern segment. This indicates a high potential of seismic activity on this segment of the Shotori fault. Manuscript profile
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  3 - Fractal analysis of the aftershocks of the 2013 Gosht-Saravan (M.7.8) earthquake, NE Makran
  Abdolreza Partabian Shoja Ansari Faride Jahandideh
  In this paper the fractal dimension of the aftershocks of the 2013 M 7.8 Gosht-Saravan earthquake and their relationship with the seismicity parameters (such as the b-value) and also the released seismic energies of the main shocks and the aftershocks are investigated. More

  In this paper the fractal dimension of the aftershocks of the 2013 M 7.8 Gosht-Saravan earthquake and their relationship with the seismicity parameters (such as the b-value) and also the released seismic energies of the main shocks and the aftershocks are investigated. The Gosht-Saravan main shock is an intraslab event with normal mechanism. No relationship between the Saravan fault and the main shock is observed. By examining the fractal dimension of the aftershocks and their relationship with the b-value it is confirmed that a linear seismic source (such as a subduction zone) exists. The slip ratio between the primary and secondary faults can be estimated by the fractal dimension. The calculated slip ratio indicates that a low portion of the slips may be related to the near surface fractures which can be verified by the shallow depth aftershocks. The earthquake occurrence in the intermediate depth, releases seismic energy and migrates to the near surface faults and fractures. The occurrence of aftershocks both near the hypocenter and at shallow depths can confirm the activity of these faults. The ratio of the total radiated seimic energy of the aftershocks to the radiated seimic energy of the main shock indicates that a high fraction of the energy related to the main shock and just a small fraction of the energy related to the aftershocks. Manuscript profile