Iranian Permanent GPS Network: Strategy and ProcessingHamid Reza Nankali Geodesy and Geodynamics Department National Cartographic Center of Iran- Tehran Azadi Sq.Meraj Ave. Po.Box:13185-1684 h-nankali@ncc.neda.net.ir Yahya.DJamour Geodesy and Geodynamics Department National Cartographic Center of Iran- Tehran Azadi Sq.Meraj Ave. Po.Box:13185-1684 Abstract: A dense and wide permanent GPS station network has been established in Iran (Tabriz-Tehran-Mashhad) and other active part of the country by National Cartographic Center of Iran(NCC). Since first of the 2005 this network and is designed both for crustal deformation monitoring and to serve as a highly precise geodetic network in Iran and consist of 107 permanent stations in first phase. Average distance between dense parts is about 25 to 30 km. Since we have collected about 1 year data , we estimated horizontal crustal displacement and velocity field with respect to the stable Eurasian plate. This new network will bring us more precise information on crustal information and geophysical phenomena such as ionosphere disturbances and water vapour too. Finally this network serve as active controlling system in Iran by GPS. 1) Introduction: The present tectonics of Iran results from north-south convergence between the plates of Arabia to south west and Eurasia to the north east (Jackson & Mackenzie 1984). It involves a continental collision (Falcon 1974) except along the Makran, its southeastern margin, where a remnant part of tetheys oceanic lithosphere subducts north works beneath south east Iran (Byrne etal.1992). Most of the deformation is accommodated in the major belts (Alborz,Zagros,Kopet-Dag) and along large strike slip lengths which surround blocks (Central Iran , Lut , South Caspian Sea) with moderate siesmicity (Jackson, Mackenzie 1984). The present-day deformation is associated with active siesmicity and destructive earthquakes that prodically shake Iran (Bam 2003). The understanding of the present day deformation will contribute to a more accurate and reliable assessment of the seismic hazard in Iran Fig(1).  Fig 1- Siesmicity of Iran According to this situation, it is important to monitor the crustal deformation using geodetic data such as VLBI,SLR,In SAR, and GPS. Among them GPS has several advantates (continuous collection, cheaper, and more compact) and therefore it is easier to construct lots of observation stations. With the recent advance in GPS receivers technology and scientific software's (Bernese-Gamit/Globk-GIPSY OASIS) and using precise satellite orbit and clock, we can achieve the accuracy for station position their velocity for geodynamic applications. So in 2005 National Cartographic Centre of Iran (NCC) started to built a GPS permanent observation network for crustal deformation monitoring and estimating geohozard in Iran. The network consist of 107 GPS observation site which distributed in the active part at the country. To reach the goals we also benefited the studies and remark of GSI(Geological Survey of Iran) and IIEES (International Institute of Earthquake Engineering and Seismology). 2) Network Configuration Iran is situated in a region of collision between two major tectonic plates: Eurasian and the Arabian plates with the convergence rate 2.5cm±2mm (vernant etal.2004) The network consist of two part: base network and regional networks. The base network consist of 41 station which distributed in Zagros-Alborz-Lut-Kopet-Dag-Central Iran- Makran and east of Iran in order to monitor the total motion and geodynamics of plates boundary. Fig 2  Fig 2- Iranian permanent GPS Network
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