Masoume Amighpey; Behzad Vosoughi; Maryam Dehghani
Abstract
An earthquake with the magnitude of 5.9 Mw occurred in Qeshm Island and Hormozgan province in November 27th 2005. 3D co-seismic deformation field caused by the earthquake are determined based on the ascending and descending interferograms and azimuth offsets. The peak to peak estimated displacement is ...
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An earthquake with the magnitude of 5.9 Mw occurred in Qeshm Island and Hormozgan province in November 27th 2005. 3D co-seismic deformation field caused by the earthquake are determined based on the ascending and descending interferograms and azimuth offsets. The peak to peak estimated displacement is about 10 cm in west, 69 cm in north and 22 cm in vertical directions. We apply strain analysis to study coseismic deformation of the earthquake. Finite element method as numerical solutions is applied in order to compute the strain tensors. Furthermore, dilation and shear parameters are derived from computed strain tensor fiel of the area. The maximum expansion and contraction are computed as 0.006 and 0.005, respectively. Moreover, the maximum shears in xy, xz and yz planes obtained by finite element method were 0.2 rad, 0.4 rad and 0.19 rad, respectively. The results represent the changes in direction and maximum expansion and maximum contraction in the direction of faults proposed by aftershock seismicity study of the earthquake. The concentration of the shear and dilation are observed in central part of island along the NW-SE oriented fault passing from central part of island. The numerical results show considerable amounts of shear and dilation in the vicinity of Qeshm fault, as well.
Zahra Mousavi; Behzad Vosoghi
Abstract
A new and significant source of information on earthquake studies has been provided by space geodesy. The data which are gathered by various techniques of space geodesy, can quantify potential of seismic activity in the region of interest. To achieve this goal, the main advantage of extra-terrestrial ...
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A new and significant source of information on earthquake studies has been provided by space geodesy. The data which are gathered by various techniques of space geodesy, can quantify potential of seismic activity in the region of interest. To achieve this goal, the main advantage of extra-terrestrial geodetic data in comparison with the conventional data from geology and seismology is the ability of this data in portraying the present kinematics of the area with faults that are unknown, too slowly slipping, or too deeply buried. Seismic moment rate, that can be calculated based on geological fault data and historical earthquake catalogue, is the amount of accumulation of earthquake potential in a region. Space geodetic data are used in the deformation analysis for quantifying strain rate tensor. The strain tensor is related to the moment rate tensor according to Kostrov formula presented in 1974 for the first time. In 1994, Ward calculated geodetic seismic moment rate by means of eigenvalues of strain rate tensor. The seismic moment rate that are calculated based on these three discipline, namely geodesy, geology and seismology can grant us a comprehensive view of seismic potential of the region. Since 1999 the National Cartographic Center (NCC) of Iran has been established and maintained a high precision geodetic network in the region of Iran. The network has 28 stations on two of the main plates, namely Eurasian and Arabian plates. This is a long term project, with planned re-observations every two years. First epoch of GPS measurements was done in 1999 and the second GPS campaign was carried out in 2001.
This paper will focus on this data to derive geodetic seismic moment rates. Our results show that south-east region and central
Alborz presents largest values of the seismic moment rates in comparison to other parts
of Iran. The moment rates in area unit are 5.7659x1015(N m-1 yr-1) and 2.0147x1015
(Nm-1 yr-1) over the predefined seismic regions of south-east and central Alborz, respectively. The derived magnitudes of the seismic moment rate show the smallest value in north-east region. The determined rate is equal to 1.0832x1015(N m-1 yr-1) in this region.
Ramezanali Mahdavi Nejad; Mohammad Gholami Nejad Saniabadi
Abstract
Dimensional accuracy in machined parts depends on the precision of spindle, which is highly affected by applied forces, itself. This precision of spindle becomes more serious when it is used for a period of long times. Therefore, stress and strain analysis of spindle is very important in the behavior ...
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Dimensional accuracy in machined parts depends on the precision of spindle, which is highly affected by applied forces, itself. This precision of spindle becomes more serious when it is used for a period of long times. Therefore, stress and strain analysis of spindle is very important in the behavior and preservation of its precision. In this paper, the forces applied to the spindle of a turning machine are calculated and analyzed. Afterwards, the spindle is simulated with MSC Visual Nastran software and analyzed due to the application of boundary conditions. According to the spindle’s stress and strain, the modal analysis has been done and the natural frequencies of the spindle are determined. The results show that, the front bearing of the spindle is the critical section and its stress and strain will be increased with feed and depth of cut. When these feed rates and depths of cut become less, the created stresses at the least speed of spindle are more in comparison with the other speeds.
