2-2-Structural Geology 
Eastern Anatolia displays most of the geological features of a collisional orogen, which is similar in many respects to the Tibetan Plateau (Şengör and Kidd 1979; Şengör 1979; Şengör and Yılmaz 1981; Dewey et al 1986; Şaroğlu and Yılmaz 1984; Barazangi 1989; Şengör and Natalin 1996; Şengör et al 2003; 2008) (Fig 4A). The GPS measurements of crustal displacements (Fig 4B) (Reilenger et al. 2006; Şengör et al. 2008), focal mechanism of the earthquakes, and the distribution of active faults (Figs 1, 2, 4 A) (Şengör et al. 2003; Bozkurt 2001; Yılmaz 2017) confirm that the eastern Turkey experiences an ongoing north-directed compressional stress (Fig 4 A) (Yılmaz 2017 and the references therein).
The present-day morphology in eastern Anatolia was developed under a significant structural control (Yılmaz 2017) (Figs 1 and 2). The major morphotectonic features, northeast, and northwest-trending hills, and depressions (Fig 1) correspond to anticlines and synclines, respectively (Fig.1) (Yılmaz 2017). There is a centrally located structural dome, which may be regarded as the center of virgation (Fig 1), the maximum indentation location. The peripheral mountains on both sides make curves around the virgation (inset in Fig 1). The strike-slip faults disperse away from this high (Figs 1, 2). The arrangement and interactions of the structures demonstrate that eastern Anatolia has undergone a complex tectonic evolution (Şengör and Kidd 1979; Şengör and Yılmaz 1981; Şaroğlu and Yılmaz 1986; Copley and Jackson 2006; Yılmaz 2017) from the time of collision along with the southeastern Anatolian suture zone in the Late Eocene. This event corresponds to a wholesale elevation reflected in eastern Anatolian stratigraphy as a marked angular unconformity (Fig 3) (Yılmaz 2019 ) ( see the accompanying paper in this volume by Yılmaz et al.).
In the East Anatolian High Plateau, the following major groups of structures are readily observed (Fig 4A);
1- NE and NW striking strike-slip faults (Figs.1and 4A) forming conjugated pairs (Şengör and Kidd 1979; Şaroğlu and Yılmaz 1984; Bozkurt 2001; Seyitoğlu et al. 2017; Yılmaz et al. 2017). The NE Striking faults are commonly longer and more prominent (Fig. 1) (Bozkurt 2001; Seyitoğlu et al. 2017). Most of these faults are young and active that generate frequent earthquakes (i.e., the Elazığ earthquake, on the 24 January 2020, Mw= 6.7, the Iran-Turkey border earthquake on the 23 February 2020, Mw=6.0, and the Malatya earthquake on the 24 January 2020 Mw=6,7).
2- Approximately E-W or ESE-WNW- striking reverse faults (Fig 4A),
3- E-W trending open and tight folds (Şaroğlu et al 1980; Şaroğlu and Yılmaz 1984;1986;1987; Koçyiğit et al. 2001; Yılmaz 2017).
4- N-S trending extensional structures (Fig 4A) (Şengör and Kidd 1979; Şaroğlu and Yılmaz 1984;1987; Yılmaz 2017).
The trends of all these structures are compatible with the N-S compressional stress field (Fig. 4A) generated from the northward advance of the Arabian Plate (Fig, 4B), which also caused the peripheral mountains to thrust over the eastern Anatolian plateau (Fig 2; 5A and 5C). Along the thrust boundary, the basement metamorphic rocks are exposed on the hanging walls (Figs 2 and 5C). As a result, the crust along the overthrust zones is thicker than the average, reaching up to 50 km (48 km beneath the Bitlis‐Pötürge massifs in the south and 50 km under the Pontide Range (Barazangi et al. 2006; Şengör et. 2003; 2008: Tezel et al. 2013; Pamukçu et al. 2007; Medved et al. 2021).
Two narrow, fault-bounded chains of depressions were formed between the central high and the peripheral mountains during Pleistocene (Figs 1, 2, 5 A and 5B). The boundary faults give the young basins their distinct rhombohedral or parallelogram geometrical patterns (Fig. 5B). The transpressional faults with the major strike-slip, coupled with reverse slip components, strike parallel with, and determine the basins’ long axes (Fig 5B). Due to the reverse slip displacements along the boundary faults, the depressions may be viewed as ramp basins or intermontane basins (Figs 5A and 5C) as exemplified from the Muş, Bingöl, Murat, Elazığ, Malatya basins to the south (Figs 1 and 5B) and the Tercan‐Aşkale, Pasinler, Kağızman basins to the north (Figs 1 and 5B). The Eastern Anatolian High Plateau may also be regarded as a giant ramp basin between the thrust elevated peripheral mountains (Fig 5A).
Within the rhombohedral depressions where normal faults define the releasing bends, the local basins were alternatively described as pull-apart basins (Keskin et al. 1998). Some volcanos were built above the extensional openings (Fig 1) (Dewey et al., 1986; Pearce et al., 1990; Keskin et al., 1998; Yılmaz 2017).
The two transform faults, the North Anatolian Transform Fault and the East Anatolian Transform Fault define the Anatolian Plate (Figs 1 and 2), which protrudes away from the area of convergence in the Karlıova Junction (KJ in Fig 1) (McKenzie 1972; Şengör et al. 1975; Şengör and Yılmaz 1981; McKenzie and Yılmaz 1991; Şaroğlu and Yılmaz 1991; Çemen et al., 1993; Aktuğ et al. 2012; Karaoğlu et al. 2017) (Figs 1, 2, and 5B). The area where the transform faults intersect is a wedge shape depression (Fig 5 B), which widens progressively as the Anatolian Plate moves away from the point of convergence (Şaroğlu and Yılmaz 1991; Karaoğlu et al. 2016) (Fig 5 B). The oldest lateral fan deposits sourced from the basin boundary faults (Fig 5 B) is Upper Pliocene (?)- Pleistocene in age (Şaroğlu and Yılmaz 1991), which sets a lower limit to the time of the westerly escape of the Anatolian Plate. The escape tectonics partitions the N-S compressional stress (Yılmaz 2017).
Associated with the development of the two transform faults and the consequent escape tectonics of Anatolia, a new tectonic regime, the Neo Tectonics, began and has drastically changed the morphotectonic character of the Anatolia and surrounding regions (e.g., Şengör 1979; Şengör and Yılmaz 1981; Çemen et al., 1993; Yılmaz 2017).
The GPS vectors in Fig 4B shows that the eastward motion of Eastern Anatolia is slower than its westward movement. Field and earthquake data indicate that the N-S compressional stress is accommodated in this region along with several small-size strike-slip faults with right-lateral displacements (Fig 2).