Numerical Simulation of Crustal Strain in Turkey from Continuous GNSS Measurements in the Interval 2009–2017

Abstract

Abstract The present study investigates the crustal strain in Turkey by using data from the Turkish permanent GNSS network (TPGN) and international GNSS services (IGS) observations for a period of 9 years, 2009 t0 2017. The positional variation of GNSS sites is studied to understand the coordinate reliability, interseismic and coseismic effects and linear velocities as well as three dimensional principal strains across the country. The study of coordinate reliability shows that the horizontal and vertical residuals in 2013 and 2015 are of the order of 100 mm per coordinate or higher than those of 2009 and 2011 and 10 times higher than those of 2017. The changes in baseline length relative to an arbitrary zero-o_set for the selected period shows that the most of the sites have displacement in the interval −10 to 10 mm but some sites have larger variations. These displacements are mostly related to motion of the Turkish tectonic plate, regional crustal deformation and small amounts of errors inGNSS positioning. The most GNSS site velocities located all over Turkey give significant information for the study. The GNSS data shows that the Anatolian plate relative to the Eurasia is moving in a western direction in the central part of Turkey and starts to move in a south-westerly direction in the west part of the country. The westward motion of Anatolia increases gradually from 20 mm/yr in central Anatolia to 30 mm/yr in south-west Turkey. The numerical simulation of the crustal strain in the Aegean region shows a maximum 1.0446×10−6 compressional principal strain rate while the second principal strain rate is zero. The strain in Central Anatolia is evidently dominated by extensional deformations and the principal strain rate reaches to 0.9589×10−6 with maximum extension. The Marmara Region network is subject to an extensional principal strain (0.6608×10−6) which is also revealed in the Mediterranean Region with a 0.5682×10−6 extension. The present analysis of GNSS data over the region may complement towards the understanding of the stability of regional tectonics and long term aseismic strain inside the country.