Time series analysis of GPS permanent stations around east Anatolia

Abstract

The eastern part of Anatolia is a significant location in the world due to its tectonically active background. It includes one of the major fault zone of Anatolia: left-lateral East Anatolian Fault (EAF), forming a boundary between the Anatolian and the Arabian plates. Its long-term slip rate as well as localizations of creeping zones, locking depth and the surface offsets can be obtained by using inter-seismic Global Positioning system (GPS) velocities and proper models. However, the quality of position time series generated from each GPS station directly determines the accuracy of the velocity estimation. The Continuous Operating Reference Stations (CORS) of Turkish National Permanent GNSS Network-Active (TNPGN-Active), mainly using the GPS measurements, covers the most area of Turkey, including the whole segments of the EAF. In the thesis duration, a limited part of the TNPGN-Active data could be archived. Then, as a thesis objective, we decided to control the quality of GPS velocities, estimated from limited data of stations around the EAF, in order to improve the GPS velocity field in this region. In this study, 2-year span GPS data from 37 sites of TNPGN-Active were processed by using GAMIT/GLOBK to generate daily position time series of each station as well as the related velocity estimates. For the GPS time series, mainly noise analysis was applied to distinguish which station is sufficient enough for using its velocity estimates. Finally, it has been found that the velocity estimates of at least three specific stations with spectral indices > 0.7 and linear trend uncertainties > 2.5 mm on horizontal components, which are MUUS, HINI and GEME, are not quite reliable with the limited 2-year data. This result will be highly likely an important reference for the campaign type GPS study along Hazar-Palu segment of the EAF in the future. To estimate a high quality velocity field, new campaign sites could be added around the problematic TNPGN-Active stations.