Earth Surface Deformation Analysis in Iran using Novozhilov's Mean Rotation Measure with Finite Element Approach

One of the most fundamental and important a new area of research in geodesy is earth surface deformation modeling at local and global scales. Also, check out the effective factors in deformation, and offers various computation methods in order to determine the movement of the Earth's crust are considered as a recent development in geodesy. In recent years, space geodetic techniques with high precision and reliability have provided new sources of information to determine the geodetic positions. This information used for the detection and quantification of surface deformations. Iran is located in a very active seismic region. Cataloge of historical earthquakes in this region shows that Iranian plateau has potential for great earthquakes in the future. Due to this high risk of natural hazard, many researchers have focused to study about geodynamic of Iran. For this purpose, in this paper a new numerical measure called Novozhilov measure of mean rotation is introduced. In the fourth decade of the 20th century Novozhilov obtained a measure of the mean rotation by modifying a previous definition produced by Cauchy. The measure introduced by Novozhilov for the mean rotation indicates the importance of the infinitesimal rotation tensors. To achieve this goal, first linear strain and rotation tensors on earth surface based on shell theory in continuum mechanics using finite element approach will be calculated and then the mean rotation measure using linear strain and rotation tensor components is determined. In this paper the results of Novozhilov’s mean rotation measure were compared with GPS block rotation rates in deg/Myr measured in the center of each block (from block model with locked faults). GPS network that is used in this paper includes 37 stations all over Iran. The computed linear strain and rotation tensors based on geodetic observations (GPS) of national permanent geodynamic network in 2008 are in a good agreement with the numerical results of previous works. The pattern of Novozhilov’s mean rotation measure over Iran shows that the highest right turn rotation is related to the region in the south of Iran including JASC, BABS, GLMT (3.113deg/Myr) stations. Also the highest left turn rotation can be seen in the north of Iran including MAVT, BIAJ, GRGN (-2.509deg/Myr) stations. The importance of Novozhilov’s mean rotation analysis on earth surface in comparison to the analysis of this measure in Cartesian system is shown by this fact that the computed measure on the earth surface is in a good agreement with the results of previous studies on blocks rotation in different areas of Iran.