Constraints on the Lithospheric Kinematics in the Aegean and Western Anatolia Unveiled by SKS Splitting Observations

Abstract

The relative convergent movement between the Eurasian, African, and Arabian plates has exerted a major influence on the tectonic evolution of Anatolia and surrounding regions (Figures 1a and 1b). It is also responsible for the W-SW directed escape motion of the Anatolian plate (e.g., McKenzie, 1972;Taymaz, 1996) and resultant seismotectonic structures. Intense earthquake activity is particularly localized along the Hellenic subduction zone, western Anatolia, the right-lateral North Anatolian Fault Zone (NAFZ) and the left-lateral East Anatolian Fault Zone (EAFZ). The geodynamic evolution of the region is shaped by the closure of the Tethys Ocean. This event had a significant influence on shaping the active tectonics of Anatolia and surroundings. The 1,500 km long NAFZ, the northern boundary of the Anatolian Plate, starts from the Karlıova triple junction in the east, and reaches to the western edge of the Aegean block by passing through the North Aegean Trough (NAT)

Depth‐Dependent Anisotropy Along Northwest Segment of the North Anatolian Fault Zone: Evidence for Paleo‐Tectonic Structures Contributing to Overall Complexity

“…In this region, the harmonic decomposition and NA modeling indicate a clear N‐S horizontal axis of symmetry (Figure 14). This slightly deviates from our NE‐SW directed SKS‐derived fast polarization azimuths that are coherent with the regional pattern (e.g., Biryol et al., 2010; Confal et al., 2016; Erman et al., 2022; Evangelidis, 2017; Evangelidis et al., 2011; Hatzfeld et al., 2001; Kaviris et al., 2018; Merry et al., 2021; Olive et al., 2014; Paul et al., 2014; Sandvol et al., 2003; Schmid et al., 2004; Yolsal‐Çevikbilen, 2014) (see the bottom layer in Figure 14).…”

“…In this region, the harmonic decomposition and NA modeling indicate a clear N-S horizontal axis of symmetry (Figure 14). This slightly deviates from our NE-SW directed SKS-derived fast polarization azimuths that are coherent with the regional pattern (e.g., Biryol et al, 2010;Confal et al, 2016;Erman et al, 2022;Evangelidis, 2017;Evangelidis et al, 2011;Hatzfeld et al, 2001;Kaviris et al, 2018;Merry Figure 14. Cartoon illustration of the sketch model inferred from our receiver function modeling and SKS splitting measurements for the study area.…”

“…This suggested the hypothesis that these faults extend deeper into the lithosphere. A recent SKS splitting study (Erman et al., 2022) that involved two‐layer splitting measurements in western Anatolia reported a lithospheric‐scale anisotropic effect on SKS phases. They explained the fault‐parallel orientation of anisotropy (at ∼120 km) at the western edge of the NAFZ by the signature of a lithospheric petro‐fabric formed during recent deformation.…”

“…Furthermore, high‐resolution 3‐D local P‐wave arrival time tomography of the crust and uppermost mantle beneath the Anatolia has revealed extension‐parallel fast velocity azimuths in the lower crust and uppermost mantle in western Anatolia (Wang et al., 2020). Early core‐mantle refracted SKS phase splitting measurements (e.g., Biryol et al., 2010; Confal et al., 2016; Evangelidis et al., 2011; Olive et al., 2014; Paul et al., 2014; Sandvol et al., 2003; Yolsal‐Çevikbilen, 2014) and two‐layer mantle anisotropy models (e.g., Erman et al., 2022; Merry et al., 2021) showed regionally consistent NE‐SW fast polarization orientation (FPO) in Anatolia. These observations were primarily explained by LPO of olivine in the asthenospheric mantle due to the mantle flow induced by slab roll‐back and/or extension beneath the Aegean Sea.…”

Tectonic Geodesy Synthesis and Review of the North Aegean Region, Based on the Strain Patterns of the North Aegean Sea, Strymon Basin and Thessalian Basin Case Studies

“…According to previous studies (e.g., [3,6]), the Hellenic Trench has undergone a retreat (approx. 580 km) since the Eocene-Miocene [7,8]. This geological phenomenon has resulted in a tectonic regime, which is characterized by N-S and NE-SW extensional occurrences in the Aegean and Anatolian regions [9,10].…”