عنوان مقاله [English]
نویسندگان [English]چکیده [English]
Most of the seismic activities in north-east of Iran are observed around the major fault systems which have mostly been distributed along the approximate direction of NW-SE. Fractal analysis was performed in north-eastern Iran by the method square-counting for the sake of which the study area was classified into 12 regions and each region was analyzed separately. Fractal dimension is ranged between 0 and 2. If Fractal dimension is approximate 0, it will indicate that the faults and earthquakes have been centered in one place. If Fractal dimension is approximate 2, it will indicate that the faults and earthquakes have been dispersed in the area. In fact, this comparative method is a vibrated action among neighbor areas. Based on the results by distancing from the main fault systems in the region that possesses the trend of NW-SE, The fractal dimension of seismicity is reduced .This indicates the existence of discontinuity in the major fault systems in the region. The high rate of fractal dimension of the regions of same Qaen, Boshruyeh and Torbat – e –Heydarieh as well as the reduction in the rate of the fractal dimension of the blocks of Birjand, Gazik and Taybad, suggest that the terminal area of the major fault systems in the east is located in the area of Taybad and Birjand blocks. On the basis of Fractal analysis of the fault zone and the study of the seismic data, most of the seismic activity in the north - East of Iran is based on the pattern of intercontinental earthquakes of low depth (mostly between 10-20 km) and occurs in relation to the primary linear sources (faults) in the area or their secondary branches. The distribution of voluminal and superficial fractal dimension of the East of Iran Also, indicates the higher seismic activity in the central and western parts in regard to other adjacent.