Applications of Global Positioning System (GPS) in geodynamics: with three examples from Turkey

Global Positioning System (GPS) has been very useful tool for the last two decades in the area of geodynamics because or the validation of the GPS results by the Very Long Baseline Interferometry (VLBI) and Satellite Laser Ranging (SLR) observations. The modest budget requirement and the high accuracy relative positioning availability of GPS increased the use of it in determination of crustal and/or regional deformations. Since the civilian use the GPS began in 1980, the development on the receiver and antenna technology with the ease of use software packages reached to a well known state, which may be named as a revolution in the Earth Sciences among other application fields. Analysis of a GPS network can also give unknown information about the fault lines that can not be seen from the ground surface. Having information about the strain accumulation along the fault line may allow us to evaluate future probabilities of regional earthquake hazards and develop earthquake scenarios for specific faults. In this study, the use of GPS in geodynamical studies will be outlined throughout the instrumentation, the measurements, and the methods utilized. The preliminary results of three projects, sponsored by the Scientific & Technical Research Council of Turkey (TUBITAK) and Istanbul Technical University (ITU) which have been carried out in Turkey using GPS will be summarized. The projects are mainly aimed to determine the movements along the fault zones. Two of the projects have been implemented along the North Anatolian Fault Zone. (NAFZ), one is in Mid-Anatolia region, and the ther is in Western Marmara region. The third project has been carried out in the Fethiye-Burdur region. The collected GPS data were processed by the GAMIT/GLOBK software The results are represented as velocity vectors obtained using the yearly combinations of the daily measured GPS data.