BULLETIN OF GEOPHYSICS AND OCEANOGRAPHY, vol.1, no.1, pp.1-18, 2024 (SCI-Expanded)
Istanbul is located south of the Black Sea and north of the Marmara Sea. The seismic
stresses and strains in Istanbul and the Marmara Sea are governed by the E-W and
NE-SW tectonic characteristics. This research aims to establish the latest crustal motion
parameters in Istanbul, utilising Global Navigation Satellite System (GNSS) surveys.
A geodetic network was established for this study, comprising 1,159 temporary and
nine permanent GNSS stations across Istanbul’s Asian and European sectors. Between
2000 and 2020, GNSS measurements were taken, and horizontal and vertical crustal
movements and velocity vector maps were produced using GNSS and Geographical
Information System (GIS) tools. The GNSS data was processed using GIPSY-OASIS, Topcon
Magnet Tools, and Leica Geo-Office software. The data was, then, analysed using ESRI
ArcGIS software, which generated thematic maps of Istanbul using ordinary Kriging and
trend surface analysis interpolation methods. The analysis results indicate a horizontal
variation of the local velocity rate in the SW direction between 14.3 and 17.1 mm per
year. Moreover, the data suggests that there is a subsidence variation between -0.7 and
-2.0 mm per year. The study results show that the northern block of the North Anatolian
Fault Zone moves horizontally towards the SW at an average rate of 16.3 mm per year.
The study findings demonstrate a notable horizontal slip rate in the northern regions,
whereas vertical subsidence is significantly observable in the eastern regions. The study
involved the creation of Voronoi cells for each temporary GNSS station, followed by the
calculation of regional shift magnitudes in the area surrounding each station. In regions
with notable horizontal and vertical slippage, it would be beneficial to increase the
number of observation stations, particularly within the extensive Voronoi cells. The longterm and continuous GNSS measurements greatly improve the study of ongoing crustal
movement and tectonic deformation processes in north-western Anatolia.