Examination of the kinematic structures in İzmir (Western Anatolia) with repeated GPS observations (2009, 2010 and 2011)

Abstract

The Western Anatolia and the Aegean Sea regions are one of the most significant seismically active and rapidly deforming fields in the world. Generally, seismic activities cause deformations and these deformations are monitored with Global Positioning System (GPS) / Global Navigation System (GNSS). In this context, GPS data were used to determine the deformation of İzmir and its surrounding to estimate the relative plate motions. In this study, the kinematic structures of the faults, which control the seismic hazard in İzmir and its surroundings, processing results of the three-year (2009, 2010 and 2011) episodic GPS observations and the estimation of displacements for 21 GPS stations were presented. The aim of this study is to examine interplate motion of the stations and their relations with the tectonic structures, seismicity and paleomagnetism and additionally, to interprete the motions of the study area relative to different block motions. Consequently, the mean motion of the study area was found approximately 25 mm/yr (towards the SSW) in the Eurasia fixed frame solution. The Aegean block fixed frame and the Anatolian block fixed frame solutions were computed relative to Euler vectors. In Aegean and Anatolian block solutions it was determined that the stations move separately, not as a group. In Euler pole solution, some stations are separated from each other and meanwhile some stations are grouped by considering the differences and similarities of the station motions. According to this solution three lines and two regions were described in the study area. The relations between seismicity and paleomagnetic studies and the kinematic structures determined in Anatolian block fixed frame and Euler pole solution were also investigated. When the Anatolian block fixed frame

Present day strike-slip deformation within the southern part of the İzmir-Balıkesir Transfer Zone based on GNSS data and implications for seismic hazard assessment in western Anatolia

“…Regional studies have suggested that a N-S extension is dominant in the region and the mean motion of the region was approximately 25 mm/year towards the SW in Eurasia fixed frame solutions. Only 4 of these studies, in which the newest measurement was made in 2012, have focused on İzmir and its immediate surroundings, where the study area is located (Aktuğ and Kılıçoğlu, 2006;Özener et al, 2012;Pamukçu et al, 2015;Çırmık et al, 2017a). However, the results herein indicated that a strike-slip tectonic regime was the main reason for the present-day deformation in the southern part of the İBTZ.…”

“…Several studies with new GPS/GNSS measurements have been conducted in western Anatolia over the last 2 decades (McClusky et al, 2000;Aktuğ and Kılıçoğlu, 2006;Reilinger et al, 2006Reilinger et al, , 2010Aktuğ et al, 2009;Özener et al, 2012;Pamukçu et al, 2015;Çırmık et al, 2017a). Regional studies have suggested that a N-S extension is dominant in the region and the mean motion of the region was approximately 25 mm/year towards the SW in Eurasia fixed frame solutions.…”

GPS derived finite source mechanism of the 30 October 2020 Samos earthquake, Mw = 6.9, in the Aegean extensional region

“…62 GNSS sites covering the region were used (Aktuğ and Kılıçoğlu 2006;Aktuğ et. al., 2009;Özener et al, 2013;Çırmık et al, 2017a;Eyübagil et al, 2021 Min. 8-h with 30s interval GNSS measurement was carried out between 5th and 8th of November 2020 at campaign type sites to calculate post-earthquake coordinates Figure 4).…”

Source modelling and stress transfer scenarios of the October 30, 2020 Samos earthquake: seismotectonic implications

“…The direction of extension (T-axis) has a dominating NNE-SSW azimuth with some events showing a roughly N-S azimuth. GPS measurements (e.g., Nyst and Thatcher, 2004;Aktug et al, 2009;Çırmık et al, 2017), as well as palaeomagnetic surveys (e.g., van Hinsbergen et al, 2010;Uzel et al, 2017), suggest that the wider İzmir area is shifted approximately 25 mm/a in a SSW direction, according to a stable Eurasia. GPS-based strain pattern estimations for the broader Aegean (e.g., Floyd et al, 2010;England et al, 2016) suggest that in our study area extension prevails in a roughly NNE-SSW direction, whereas contraction is almost negligible.…”