The existing active fault map of Turkey (Emre et al., 2013) does not explain the correlation with all seismic events, especially in southeastern Turkey. Most of the active faults are of a strike-slip nature and are recognized after major earthquakes in eastern Turkey (i.e. Çaldıran, Varto, Bingöl). Active thrust fault lines are rare on the MTA map, with the exception of the Bitlis Suture Zone, and the Van and Cizre Faults, whose limited identification is probably due to thrust-related major earthquakes. For example, the 1975.09.06 Lice earthquake (Ms: 6.7) was attributed to the Bitlis Suture Zone (Arpat, 1977;Jackson and McKenzie, 1984). The Van Fault Zone was recognized and mapped after the 2011.10.23 Van earthquake (Mw: 7.1) (Zahrandik and Sokos, 2011), which taught us that blind thrusts are important seismic sources in eastern/southeastern Turkey and that they need to be studied in detail.Southeastern Turkey presents several thrusts/blind thrusts that can be determined by using asymmetrical fold axes (Suppe, 1983;Mitra, 1990;Suppe and Medwedeff, 1990). We interpret these structures, together with their counterparts in northern Syria and Iraq, as having

Turtleback surfaces are common elements of highly extended terrains all over the world. This paper presents a 3D model explaining the formation of turtleback surfaces based on field observations made on the Horzum Turtleback of the Alaşehir graben, western Turkey. Three essential features have been determined as forming a turtleback surface. These are 1) the rolling hinge mechanism on a normal fault system, where the initial fault stays operational after forming second and third normal faults in its hanging wall; 2) relay ramps between initial fault segments; and 3) a synextensional intrusion on the shear zone of the initial normal fault at midcrustal level. The strike-slip tectonic setting is not among the essential features as suggested recently for Death Valley turtlebacks.

Although these fault zones are considered to be secondary structures, their roles in the internal deformation of the Anatolian plate are very important for seismic hazard assessment, such as, for example the Eldivan-Elmadağ pinched crustal wedge (Seyitoğlu et al., 2000(Seyitoğlu et al., , 2009. One of these subordinate structures, the Eskişehir Fault Zone, which extends from İnegöl (Bursa) to Cihanbeyli (Konya) (Figure 1), is a relatively well-studied example; however, there is no consensus about its age or its role in the deformation of the Anatolian plate.The Eskişehir Fault Zone was drawn on the regional geological maps of Ketin (1968), Şengör et al. (1985), and Şaroğlu et al. (1987). Later, Şaroğlu et al. (2005) presented its subdivisions as the Dodurga, Kandilli, İnönü, Osmangazi, and Kaymaz segments.A regional significance has been attributed to the Eskişehir Fault Zone. Barka and Reilinger (1997) suggest that this fault zone, together with the Fethiye-Burdur Fault, constitutes the border between central and west Anatolian neotectonic subdivisions. Koçyiğit and Özacar (2003) also proposed the Eskişehir Fault Zone as a border of the West Anatolian extensional province. The evaluation of Yaltırak ( 2002) is quite different, as according to that study, the Eskişehir Fault Zone extended from Thrace to Central Anatolia and the North Anatolian Fault Zone cuts the Eskişehir Fault Zone in the Sea of Marmara.

No abstract

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