The East Anatolian Fault: geometry, segmentation and jog characteristics

Abstract A detailed account is given of the fault geometry and segment structure of the East Anatolian Fault Zone as a whole based on mapping of active faults, supported by available seismological and palaeoseismological data. We divide the East Anatolian Fault into two main strands: southern and northern. The main southern strand is c. 580 km long between Karlıova and Antakya, and connects with the Dead Sea Fault Zone and the Cyprus Arc via the Amik triple junction. The northern strand, termed the Sürgü–Misis Fault system, is c. 350 km long and connects with the Kyrenia–Misis Fault Zone beneath the Gulf of İskenderun. We infer that slip partitioning between the main and northern strands of the East Anatolian Fault accommodates 2/3 and 1/3 of the slip rate of the lateral motion between the Arabian and Anatolian plates, respectively in the Çelikhan–Adana–Antakya region. Taking account of the time elapsed from the latest events on the East Anatolian Fault, we suggest that the Pazarcık and Amanos segments have the potential to produce destructive earthquakes in the near future. Supplementary material: The data and interpretations given here are supported by five additional annotated field photographs and two tables of factual data, these are available at www.geolsoc.org.uk/SUP18568

The seismically active left-lateral East Anatolian Fault (EAF) is one of the major intra-continental transform faults in the Eastern Mediterranean region (Fig. 1). Together with the right-lateral North Anatolian Fault (NAF), it accommodates the westward extrusion of the Anatolian microplate (AN) (McKenzie 1972(McKenzie , 1976Ş engör 1979, 1980Jackson & McKenzie 1984;Ş engör et al. 1985;Dewey et al. 1986). The EAF zone constitutes a complex left-lateral strike-slip fault zone that separates the AN from the Arabian (AR) plate.
Many studies refer to segmentation of the EAF (Arpat & Ş aroglu 1972;Arpat & Ş aroglu 1975;Muehlberger & Gordon 1987;Barka & Kadinsky-Cade 1988;Herece & Akay 1992;Ş aroglu et al. 1992a;Westaway 1994;Herece 2008).  proposed the existence of five segments based on variations in trend and geometry, while Barka & Kadinsky-Cade (1988) suggested the existence of 14 segments based on the location of geometric discontinuities, the extent of surface ruptures and the characteristic seismicity of the fault zone between Türkoglu and Karlıova. Ş aroglu et al. (1992a) recognized six segments between Karlıova and Antakya where there are stepovers and changes in strike. Herece (2008) defined 11 geometric segments for the same length of the EAF.
Other researchers have investigated stepover and bend structures along the EAF zone, for example: a probable right-handed stepover between Palu and Bingöl (e.g. Ş aroglu et al. 1992a); a sag pond or left stepover at Lake Hazar (e.g. Mann et al. 1983); a right-stepping bend where the EAF intersects with the Bitlis suture (e.g. ); a pull-apart basin formed by left stepover between segments of the EAF in the Gölbaşı region (e.g. Barka & Kadinsky-Cade 1988); and a pull-apart basin developed at the regional triple junction (Westaway & Arger 1996).
Studies based on detailed field mapping of the whole extent of the EAF (Ş aroglu et al. 1987;Herece 2008) suggest that the offset between Karlıova and Kahramanmaraş may vary by 20 -25 km or 14.5 -24 km, respectively. The data from along the fault have been interpreted to suggest an average slip rate of c. 8.3 mm a 21 between Türkoglu and the Karlıova triple junction (Herece 2008). Geodetic studies (McClusky et al. 2000;Reilinger et al. 2006) of the fault between Karlıova and Türkoglu reveal a 9 + 2 mm a 21 present-day slip rate, which is generally consistent with data from the Late Pliocene. The same studies indicate a 6.8 mm a 21 slip rate between Kahramanmaraş and Antakya on the Amanos Fault or an extension of the EAF. This suggests a decrease in slip rate along the plate boundary between Kahramanmaraş and Antakya. Quantitative kinematic models published by Westaway (2003Westaway ( , 2004 reveal that the slip between the AR, African (AF) and AN plates has been mainly accommodated within a broad zone of deformation, but this still needs further explanation based on detailed fault geometry.
The main aim of this study is to explain the detailed fault geometry and segment structure of the EAF based on the mapping of active faults, supported by available seismological and palaeoseismological data, and to discuss the structural linkage to the other major faults in the region. This study also provides data to help assess seismic hazard along the EAF and for the wider Eastern Mediterranean region.

The East Anatolian Fault
During our study the whole of the EAF was remapped in detail at 1:25 000 scale and digitized in a GIS environment based on an interpretation of 1:35 000-and 1:10 000-scale aerial photos, coupled with detailed field studies. The distribution of faults within the EAF was specifically investigated in a broad zone in the western part of the Ç elikhan area (Fig. 1). The length of the segments, the characteristics and the size of the jogs -essential inputs for seismic hazard analysis -were determined for the whole of the EAF (Table 1). Seismic gaps were recognized on some segments of the EAF based on historical and instrumental earthquake data. In addition, structural links between the EAF and other major faults of the region, that is the DSF, the CA and the KMZ, are also considered.
The EAF (Figs 1 & 2) exhibits a narrow deformation zone between Karlıova and Ç elikhan where it takes the form of a single fault trace except for jog structures. However, west of Ç elikhan it is separated into northerly and southerly fault strands and becomes a wide deformation zone. The strands are divided into fault segments based on fault jogs such as stepovers and bends and by abrupt changes in the general strike of the fault. The lengths of the segments vary between 31 and 112 km, while their strikes vary from eastwest to N758E. Fault jogs cause some changes in the general orientation.
The fault 'strand' described in this study is composed of several fault segments which bifurcate from the fault system to form another fault zone or fault system. The 'segment' corresponds to the 'geometric segment ' of McCalpin (1996), which is based on fault jogs such as fault stepovers and bends and by abrupt changes in the amount of slip along the fault strike. We also utilize available seismological and palaeoseismological data in our study of segmentation. The segments described  (1996). We use the terms 'fault section,' or simply 'section' and 'part' for convenience, without implying any particular geological or seismological significance. Also, for precision we revise the names of some of the segments and the jogs along the EAF.

The main strand
The southern strand is the main fault strand (see Fig. 2) that forms the c. 580-km-long plate boundary between Karlıova and Antakya. The fault segments of the main strand, from NE to SW, are as follows: the Karlıova, Ilıca, Palu, Pütürge, Erkenek, Pazarcık and Amanos segments (see Table 1). Quaternary -Holocene activity of the segments are represented by exceptionally active left-lateral faulting features such as offset channels, topographic saddles, shutter ridges, pressure ridges, sag ponds and linear fault valleys.

Karlıova segment
The segment (Fig. 3) begins at the intersection of the NAF and the EAF at the eastern corner of the Karlıova basin and extends as a conjugate to the NAF. This intersection is well known as the Karlıova triple junction (Ş engör 1979;Ş aroglu 1985;Ş engör et al. 1985;Ş aroglu & Yılmaz 1991), which is located between the Kargapazarı and Karlıova segments of the NAF and EAF, respectively. The Karlıova segment is connected to the Ilıca segment by the Göynük paired bend (Fig. 3). The Karlıova segment consists of right-stepping sections varying in length over the range 4 -12 km (Fig. 3). The 4-km-long northeastern section exhibits an en echelon structure created by left stepover (0.5-2.5 km long) with a northwards-convex geometry. The sections between Sakaören and Kıraçtepe in the SW exhibit a simple strike-slip character. However, these sections deviate into a small double bend (1 km wide) and stepover structure around Serpmekaya and Boncukgöze. At its southwestern end the segment is represented by a 1.5-km-wide fault zone. The length of this fault zone is c. 10 km and involves a paired bend at Göynük. Active left-lateral faulting features are observed along this segment. In two areas, especially north of Sakaören and south of Serpmekaya, the fault trace clearly transects alluvial plains and fans with fresh fault scarps being visible in the field. The amount of left-lateral offset in stream channels varies from several metres to a few hundred metres. A 3.5 m offset has been recorded on the fault trace 1 km SE of Boncukgöze (Herece 2008). This is clear evidence of historical surface rupture that can be correlated with the 1866 earthquake of Ms 7.0, as determined by Ambraseys and Jackson (1998) for the region.

Ilıca segment
The segment traverses the mountainous area between Göynük and Ilıca (Fig. 3) forming largescale shutter ridges and offset river valleys. This segment is represented by a single fault trace that is well exposed along the Göynük River valley. However, the fault is affected by a 100-m-wide right stepover at Alatepe. The fault then splits into three branches west of Ilıca and terminates north of the Bingöl plain. Hot-water springs with associated travertine units characterize the fault section near Ilıca. The fault cuts metamorphic rocks of Palaeozoic age and volcano-sedimentary rocks of Mio-Pliocene and Quaternary age, including travertine and alluvium. At Hacılar, the cumulative leftlateral offset in the Azizanyaylası stream valley is c. 1 km (z in Fig. 3).
A correlation of the metamorphic units cropping out on the opposing fault blocks in the Göynük River valley has yielded fault offsets of 14.5 -15 km (Seymen & Aydın 1972;Herece 2008) or 17 km (Arpat & Ş aroglu 1972;Ş aroglu 1985). We measured the offset by comparing an anticline axis cut by the fault in metamorphic rocks between Suduragı in the southern block with the same structure at Ilıca on the northern block. This gives an offset of 17 km (x and y in Fig. 3), compatible with that suggested by Arpat and Ş aroglu (1972).
The 1971 Bingöl earthquake of Ms 6.8 occurred along the EAF between Karlıova and Bingöl (McKenzie 1972). A discontinuous 35-km-long surface rupture with a maximum offset of 0.25 m has been reported between the Göynük bend and Bingöl plain (Arpat & Ş aroglu 1972;Seymen & Aydın 1972). The surface faulting on the Karlıova segment appears not to have extended NE of the Göynük bend. Our interviews with eyewitnesses in 2009 confirmed this. In previous studies the Karlıova and Ilıca segments were identified as a single segment of the EAF. However, we now divide this fault into two segments which are interconnected by the previously unrecognized Göynük paired bend (12 km long and 1.5 km wide).

Palu segment
This segment is bounded by the Gökdere restraining bend and the Lake Hazar releasing bend, which together represent the largest jog structures along the EAF (Fig. 4a). This fault segment displays complex jog terminations at both ends and can be divided into three sections.
The eastern and mid-section are separated by a 0.5-km-wide left stepover south of Yamaçaova. This consists of three subparallel faults splaying towards the Gökdere restraining bend. While the northerly and southerly faults form the boundary (4) secondary fault; (5) syncline; (6) anticline; (7) undifferentiated Holocene deposits; (8) undifferentiated Quaternary deposits. 'x' and 'y' denote piercing points. of bend, the middle fault connects to the inner structures of the bend. The distribution of the main shock and of aftershocks indicate that the Karakoçan earthquake of 8th March, 2010 (Mw 6.1) was generated along the northern boundary fault (Emre et al. 2010;Tan et al. 2011). However, no known surface faulting relates to this event except for some fissure cracks (F. Ş aroglu, pers. comm. 2010).
The 22.5-km-long central section is a single trace between Yamaçova and Ö rencik. The fault traverses the northern slopes of the Murat valley as far as Palu. Topographic saddles and left-lateral drainage offsets characterize this section. In the same area, a 200-m-long left-lateral offset was measured in a valley cut by the fault. A displacement of 2.5 m was measured on a stone field boundary, which probably represents the most recent local surface rupture (Fig. 5a). The fault then follows the southern bank of the Murat River where it cuts folded Pleistocene terrace deposits.
The western section of c. 40 km length extends between Keban dam reservoir and Lake Hazar. The area between Kumyazı and the Keban dam reservoir clearly exhibits exceptional left-lateral active strike-slip morphology. Left-lateral offsets observed in gullies cut into alluvial fans on the northern slopes of Orta Hill vary in length by up to a few tens of metres (x and y in Fig. 5b). The western fault section diverges into two main branches to the east of the lake. The northerly branch represents the main fault with mainly strike-slip morphology. The southerly branch has a component of normal dip-slip.
Fresh fault scarps and offsets varying between 2.5 and 4.0 m enable us to make interpretations about the latest surface faulting. The latest historical earthquake (Ms 7.1) occurred on the Palu segment on 3rd May, 1874 (Ambraseys 1988;Ambraseys & Jackson 1998). According to historical records, the resulting damage was greatest between Lake Hazar and Palu (Ambraseys 1988). Both historical (Ambraseys & Jackson 1998) and palaeoseismological findings (Ç etin et al. 2003) indicate that surface rupturing took place during this event. On the western section of the segment, east of Lake Hazar, a 2.6 m lateral offset was measured on the rupture zone (Herece 2008). As noted above, the displacement was 2.5 m on the eastern section of the segment; east of Palu both of these localities are close to the ends of the segment. In contrast, we measured the average displacement of the 1874 earthquake as 3.5 + 0.5 m (x and y in Fig. 5c) along Orta Hill in the central part of the segment. Fresh fault-related topography is more clearly expressed along this part of the segment.
Reflecting its sinusoidal trend, the segment varies from transtensional to transpressional modes from east to west. The segment comprises sections with lengths varying from 21 to 28 km, separated from each other by restraining stepovers and a bend c. 0.5 km wide. The segment is characterized by two parallel faults 9 km long to the west of Lake Hazar. Around Doganyol the segment cuts the 1000 m-deep antecedent valley of Fırat River in which the primary drainage was established during the Late Pliocene. We measured an 11 km left-lateral offset in the valley to the SW of Lake Hazar (x and y in Fig. 4b). This represents the total fault offset from Pliocene to Recent time, in agreement with Herece (2008). Systematic leftlateral offsets are developed in the tributaries of the Ş iro River along the southern slopes of the valley. These vary between several tens of metres to one kilometre in length. For example, cumulative left-lateral offsets of c. 550 and 450 m were measured in the Delan and Bobik rivers (Fig. 4b). The fault trace comprises systematic right-overlapping sections and adjoins the Yarpuzlu double bend in the west. For c. 6 km towards the Yarpuzlu bend, the fault shows an increase in reverse components. Fresh Holocene fault scarps occur on the Pütürge segment, although the timing of the last surface rupture is unknown. The 1875 (Ms 6.7) and 1905 (Ms 6.8) earthquakes (Ambraseys 1988) might have been generated along this segment.

Erkenek segment
The Erkenek segment is characterized by 2-15-kmlong sections separated by right and left stepovers, each less than 0.5 km wide (Fig. 6a). The segment is connected to a double restraining bend at its eastern end at Yarpuzlu. Towards the west, the fault traverses a Late Mesozoic accretionary prism (Herece 2008) extending as far as the Göksu Rivers. It then follows the southern flank of the Göksu River valley exhibiting a left-lateral offset of 13 km (Ş aroglu et al. 1992a) (x and y in Fig.  6a) until it terminates at the Gölbaşı releasing stopovers, marking its western end.
The whole of this segment is characterized by active left-lateral strike-slip features. The drainage network is offset by several metres to 0.5 km in Late Pleistocene and Holocene sediments south of Ç elikhan. South of Kurucaova the fault exhibits by a fresh scarp cutting recent alluvial fans, indicative of the last surface faulting event on this segment. The fault cuts a mountainous terrain and the valley slopes westwards as far as Lake Gölbaşı. Distinctive linear features can be recognized in the recent morphology.
Total offsets of 26 and 22.5 km were suggested by Herece (2008) based on a comparison of the Late Mesozoic Koçali Complex and the Malatya Metamorphics that crop out on both sides of the fault. The last surface rupture was probably caused by the 1893 earthquake of Ms 7.2 (Ambraseys 1988;Ambraseys & Jackson 1998). A 4.5 m leftlateral displacement in a gully channel south of Ç elikhan was attributed to this earthquake (Herece 2008).

Pazarcık segment
The overall shape of the segment is slightly sinusoidal, with the eastern half of the fault being concave to the north and the western half of the fault concave to the south (Fig. 6b). The segment extends between the Gölbaşı releasing stepover and the Türkoglu releasing bend.
The eastern section of the segment bounds the southern side of the Gölbaşı Quaternary basin and passes through a 250-m-wide left-stepover. The 29-km-long middle section traverses mountainous terrain where a 4-14-km-long en echelon pattern of faults is separated by left-oversteps, varying in length from 250 to 600 m. Rivers with a transverse trend to the fault are systematically offset along a c. 20 km section in the Karaagaç region. The average offset in this section is c. 4 km (x and y in Fig. 6b), as measured by Ş aroglu et al. (1992a). The western left section overlaps the central section for 3 km. The western section is divided into two nearly equal parts by a leftstepover.
The fault separates alluvium from ophiolitic rocks from Tevekkelli westwards to the end of this segment. Fault scarps are obvious with an uplifted northern block. Left-lateral offsets of up to 1.3 km are observed in riverbeds. The fault is entirely within an alluvial plain near its western tip and terminates in the Lake Gavur pull-apart basin. The northern block is again uplifted within the alluvial plain, where the Aksu River has been incised to form an antecedent valley.
The geological offsets varying from 19 to 25 km have been suggested for the Pazarcık segment (Yalçın 1979;Westaway et al. 2006;Herece 2008). An offset of 5 + 0.2 m in a stream c. 4.5 km SE of Elmalar has been attributed to the 1513 earthquake (Herece 2008). A 9 mm a 21 Holocene slip rate has been suggested based on recent palaeoseismological studies (Meghraoui et al. 2006;Karabacak et al. 2011). The authors suggested that the surface ruptures on this segment were due to the 1114 and 1513 earthquakes.

Amanos fault segment
The Amanos fault segment of the EAF (Fig. 7) comprises three sections, here referred to as the Nurdagı, Hassa and Kırıkhan sections. The 40-km-long Nurdagı section begins at Lake Gavur, and then mostly transects alluvial fans and basement rocks where it generally follows an erosional depression filled with alluvial fans. The fans are clearly cut by a 2.5-m-high fault scarp. The section joins the Islahiye releasing bend at its southern end. This bend corresponds to a 3-km-wide and 7-km-long depression filled with Quaternary alluvial deposits and basaltic lavas that were erupted from volcanic cones within the bend. Both the east and the west side of the depression are bounded by dominantly oblique normal faults.
The 45-km-long Hassa section extends between the Islahiye bend and the 1.5-km-wide Demrek restraining stepover (Fig. 7). The fault transects basements rocks, Quaternary basalt and alluvial deposits. Cumulative left-lateral offsets of basalt and the drainage patterns vary from 325 to 600 m (Yurtmen et al. 2002). Based on the same offsets, Seyrek et al. (2007) suggested a slip rate of 2.89 mm a 21 with a vertical component of slip of 0.2 mm a 21 on the base of Pleistocene basalt. Adjacent sections of the Demrek stepover exhibit a widespread pattern of left-stepping en echelon faults that range from 1 to 7 km in length. A volcanic cone occurs within the bend east of Aktepe. The Kırıkhan section begins from the Demrek stepover and has a concave geometry (Fig. 7). The 30-km-long fault traverses basement rocks, Quaternary volcanics and alluvial deposits and terminates around Topbogazı. Offsets of a volcanic cone and the surrounding lavas are estimated as c. 425 m (Yurtmen et al. 2002).
The 1822 earthquake of M 7.5 has been suggested to have been generated from the Amanos segment to produce a 200-km-long surface rupture (Ambraseys & Jackson 1998, Seyrek et al. 2007). However, we observed no evidence of fresh faultrelated topographical features that we would expect to be partly preserved under the semi-arid climatic conditions that have prevailed since the 1822 event.

Northern strand: Sü rgü -Misis Fault system
The northern strand, which we term the Sürgü -Misis Fault (SMF) system, splits from the EAF at Ç elikhan and runs towards the Gulf of İskenderun (see Fig. 2). The left-lateral strike-slip SMF system extends for c. 380 km between Ç elikhan and Karataş. The fault system divided into two strands separated by the Göksun bend. The 160-km-long eastern strand, located between Ç elikhan and Göksun, has a general east -west trend. The fault system consists of the Sürgü and Ç ardak fault segments that pass into a complex restraining bend at Nurhak (see Fig. 2). The strike of the fault system changes by an average of 458 at the Göksun bend and then runs generally NE -SW. The western strand successively divides into segments, namely the Savrun, Ç okak, Yakapınar, Andırın, Karataş, Toprakkale, Yumurtalık and Karataş fault segment (see Fig. 2; Table 1). These segments exhibit distinctive active left-lateral fault features such as offset channels, shutter ridges, topographic saddle and fresh fault scarp.

Sürgü Fault
The Sürgü Fault (Figs 2 & 8a) splits from the EAF west of Ç elikhan and terminates in the Nurhak Fault complex. This fault exhibits a sinusoidal shape and is characterized by a shutter ridge, 1 km wide and 17 km long in its eastern part. Recent deposition in this area has resulted from alluvial infill of a basin created by this shutter ridge. The fault then traverses westwards for 20 km along the southern flanks of the Sürgü River valley, where tributaries and intervening ridges are offset systematically. The western tip of the fault is represented by two subparallel faults 5 km apart that then merge with the Nurhak area of fault complexity. An offset of the fault trace across the surface of a Holocene alluvial fan indicates that Holocene surface faulting occurred along the Sürgü Fault during a large earthquake. The 1986 earthquake of Ms 5.8 (Taymaz et al. 1991) took place on the Sürgü Fault but without any observable surface rupture.

Ç ardak Fault
The 85-km-long east-west trending Ç ardak Fault is the longest segment of the SMF system. The fault, which is located between Nurhak and Göksun, is divided into eastern and western sections separated by a 0.5-km-wide right-stepover (Fig. 8b).
The 35-km-long eastern section is relatively linear with a general strike of N758W and connects with the Nurhak area of fault complexity. Cumulative systematically left-lateral offsets vary from 100 to 135 m in rivers incised into large alluvial fans between Barış and Gözpınar ( Fig. 9a, b). West of Ekinözü the fault cuts the Ceyhan River valley in a 3-km-wide zone, forming a c. 11-km-long leftlateral bend (x and y in Fig. 8b). This bend is considered as the total offset of the fault.
The 50-km-long western section juxtaposes rock units related to Berit Mountain with a volcanic complex on its northern block. This section includes the Göksun bend, which trends N458E at its western tip. The fault cuts former thrust faults and folds and clearly exhibits an active left-lateral slip morphology (Fig. 9c). Holocene river incisions into alluvial fans are systematically offset by the fault. Average offsets of 60 m were measured on the base of Last-Glacial-aged fans in five river channels west of Fındık (Fig. 9d), implying a slip rate of 2.5 mm a 21 .
A 20-km-long section with a N408E trend connects the Savrun Fault with the Göksun releasing bend, forming a sharp topographic break between the Göksun plain and Berit Mountain. Holocene fault scarps vary from 0.5 to 5 m with a downthrow to the west, as observed on small alluvial fans in the south margin of the plain. The fault then traverses the Meryemçilbeli river valley in mountainous terrain, cutting terrace deposits on its northern flanks. The tributaries incised into the terrace surfaces have been cumulatively displaced by c. 20 -30 m. Left-lateral offsets of c. 5 m clearly displace gully channels on the fault trace. The southern section is 41 km long with a N408E trend, and follows the flanks of Gezit Mountain and the Savrun

Ç okak Fault
The Ç okak Fault (Fig. 10) is separated from the Savrun Fault by a 4-km-wide, 7-km-long leftstepover, where the Ç okak pull-apart basin is developed. The main part of the segment is characterized by a left-lateral strike-slip morphology at the southern end of the basin and then traverses a limestone plateau. Karstic landforms exhibit left-lateral offset on aerial photographs. An offset of c. 2.5 km in the Keşişdere canyon represents the total offset of the fault during Late Pliocene-Quaternary time (x and y in Fig. 10).

Toprakkale Fault
A 0.5-km-wide restraining stepover occurs in the middle of the segment, dividing the segment into two sections. The 30-km-long southern section extends to the Delihalil volcanic cone (Fig. 10). This section is characterized by a normal component of downthrow to the west around Toprakkale, where smaller volcanic cones occur near the fault trace. Fresh fault scarps, 2-5 m high, are observed in Quaternary basalt. In this area, the fault follows the valley of the Ceyhan River for c. 12 km and marks the contact between Early Miocene and Plio-Quaternary formations. Left-lateral river offsets of 20-30 m were measured in Holocene tributaries of the Ceyhan River. Rare shutter ridges are observed south of Selverler. A 5-km-long fault segment cuts Quaternary basaltic lavas in the Karagedik area. The northern section traverses a hilly terrain for c. 20 km, terminating at Boynuyogunlu (Fig. 10).
The slip rate of the fault during the Holocene is estimated as c. 2-3 mm a 21 based on 20-30 m geomorphological offsets. Instrumental earthquake records along the fault indicate recent activity (Ergin et al. 2004). The locations of the historical earthquakes in 1114 (Ms 7.0) and 1115 (M 6.3) are inferred to be close to the fault zone (Ambraseys 1988).

Düziçi-İskenderun Fault Zone
This fault zone comprises NW-striking normal faults between strands of the EAF (see Fig. 2). The fault zone delimits the Amanos Mountains in the west. The fault zone is divided into three fault segments, here referred to as the Düziçi -Osmaniye, Erzin and Payas segments.
The 45-km-long NE -SW-striking Düziçi-Osmaniye segment forms a 10-km-wide zone that exhibits right-stepping fault features (Fig. 10) and also includes synthetic faults. The main faults traverse a variable landscape along the foot of the Amanos Mountain. North of the Osmaniye region, the location of the fault is indicated by distinct fault scarps up to 10 m high and by triangularshaped dissection of Pleistocene fans. In the Düziçi region, Quaternary fans are tilted towards the fault by a 15 -208-dipping plane, utilizing a 55 -658 down-to-the-west fault. A 4-5-m-high scarp indicates the latest surface faulting. The maximum height of the fault escarpment is c. 1000 m, which corresponds to the depth of incision of the Sabunsuyu valley which is located on the footwall. Synthetic faults cut Quaternary alluvial fans, as represented by fresh fault scarps between Düziçi and Aslantaş dam and also by basaltic lavas.
The Erzin segment comprises parallel faults with a general strike of N15-208E within a 2 -4-km-wide zone that transects Plio-Quaternary alluvial fans. The faults on the fan surface form a step-like morphology in which the hanging walls are tilted to the east. The presence of up to 80-90-m-high fault scarps reflects the cumulative vertical offset. Fresh fault scarps c. 5 m high cut alluvial fan surfaces at both the northern and southern ends of the Erzin segment, and provide evidence of Holocene rupturing. In a highway road-cutting south of Yeşiltepe, the fault plane traverses fan deposits and has a dip of 658 down to the west.
The 26-km-long Payas Segment is located east of the Gulf of İskenderun; it trends at N108E and dips at 65-708 to the west (see Fig. 2). This fault segment is made up of 5 -8-km-long sections. It delineates a sharp contact between Mesozoic carbonates and Quaternary alluvial fans. The fault trace is characterized by topographical steps on alluvial fan surfaces.

Yakapınar Fault
The left-lateral strike-slip Yakapınar Fault forms the contact between a hilly area dominated by Miocene siliciclastic sediments and the Ceyhan plain, which is characterized by Quaternary sediments in the east. The fault consists of two straightsided sections separated by a 5-km-wide stepover. Left-lateral offsets of stream channels, elongate ridges and topographic saddles indicate Quaternary strike-slip faulting. The 1998 Adana earthquake of Mw 6.2 (Aktar et al. 2000) was generated along this fault. The 1945 earthquake of Mw 6.0 (Kalafat et al. 2011) and the 1266 earthquake of Mw 6.3 (Tan et al. 2008) can both be correlated to the Yakapınar Fault.

Yumurtalık Fault
This fault, which runs parallel to the north coast of Iskenderun Bay, consists of two sections divided by a 2-km-wide by 4-km-long releasing stepover near İncirli (Fig. 11). The stepover area is the locus of transtensional deformation and is characterized by dip-slip oblique faults. Quaternary basalt appears to have erupted from the stepover. The eastern and western sections of the fault are 16.5 and 24.5-km-long and trend in N508E and N588E directions, respectively.
The rectilinear eastern section clearly transects Quaternary volcanic rocks. A fresh fault plain exposed in a road-cut is indicative of Quaternary strike-slip faulting. The western section has a sinuous trend and generally juxtaposes the Miocene Karataş and Kızıldere formations (Kozlu 1987). The section cuts bedding planes and fold axes obliquely in both of these formations. Within the fault zone, coarse siliciclastic beds forms hogbacks as a result of selective erosion. At Demirtaş, the fault then cuts Miocene formations with Pleistocene caliche. South of Sugözü, we measured offsets of 8-10 m in two gullies and a cumulative offset of 40 m in a stream valley. This indicates a Holocene slip rate of c. 1 mm a 21 for the fault.

Karataş Fault
The Karataş Fault borders the southern margin of the Misis Mountains (Fig. 11) where it runs almost parallel to the Yumurtalık Fault and shows a slightly sinuous trend. A 5-km-wide restraining bend is present between Haylazlı and Zeytinbeli, near the centre of the fault segment (Fig. 11). The bend causes an 88 deflection in the general trend and separates the fault in the eastern and western sections. The western section is 30 km long, trending N378E and extending between Karataş and Haylazlı. The eastern fault section between Zeytinbeli and Sarımazı is c. 34 km long. The fault transects the Karataş Formation and separates this formation from Quaternary alluviums. Shutter ridges and topographical saddles were observed along the trace of the fault. In Kurtkulagı and Demirtaş region, left-lateral offsets varying from 10 to 50 m were observed within Late Quaternary-Holocene drainage by the fault trace.

Fault jogs
The ends of the strike-slip fault ruptures are typically related to large jog structures (stepover width (d) . 5 km) or combinations of moderate-sized jog structures (1 , d , 5 km) that commonly comprise releasing stepovers (Barka & Kadinsky-Cade 1988). Stepovers of width .4 -5 km can terminate in a displacement of 5 m or more based on historical earthquake data from strike-slip faults worldwide (Lettis et al. 2002;Wesnousky 2006). However, the jog length that is required to slow or stop rupture propagation still requires explanation. In addition, there are known examples of fault jog-related earthquakes (M . 6) forming complex ruptures and also of major faults rupturing fault jogs (Arpat 1971;Barka & Kadinsky-Cade 1988;Bayarsayhan et al. 1996;Harris et al. 2002;Duman et al. 2005;Wesnousky 2006;Nakano et al. 2010).
The characteristics and size of the EAF jogs were specifically determined during this study (see Table 1). The widths and lengths of the restraining jogs vary from 1.5 to 25 km and from 6 to 45 km, respectively. Of these, the Gökdere and Yarpuzlu bends form substantial structural complexities, as explained below. The Gökdere bend is an exceptionally large restraining jog and exhibits an uplifted morphology. The corresponding releasing jogs are represented by large-scale pull-apart basins, such as Lake Hazar and Lake Gölbaşı.

Göynük paired bend
This bend occurs between the Karlıova and the Ilıca segments due to an 88 strike variation (Fig. 12). The fault jog comprises two bends representing a narrow, elongate topographic uplift and depression. Towards the jog, both the Karlıova and Ilıca segments splay into sinuous branches that gradually curve into the bend. The Karlıova segment limits the NE part of the bend with right-stepping en echelon faults that result in transpression and a push-up structure. The Ilıca segment bounds the SW part of the bend with left-stepping en echelon faults causing transtension and resulting topographic depressions. A more linear fault also occurs within the bend. The western boundary faults of the Karlıova basin join the Göynük paired bend within a complex fault area.

Gökdere restraining bend
The Gökdere bend is the largest jog structure observed along the EAF and reflects a c. 178 change in strike of the EAF. The Gökdere bend is associated with a push-up structure, 45 km long by 25 km wide (Fig. 13). The bend region is characterized by deeply dissected mountainous terrain. The southern edge of the bend is delimited by the Murat River, which was tectonically incised to a depth of 700 and 1000 m during Quaternary time (Ş aroglu et al. 1992a). Up to 600 m of tectonic uplift of the bend area took place during the same period based on a comparison of elevated terrace deposits (Herece 2008). In the east the bend is bounded by the Bingöl basin, which has been interpreted as a pull-apart basin related to the Genç fault segment of the EAF (Arpat 1971;Arpat & Ş aroglu 1972;Ş aroglu et al. 1987, 1992aBarka & Kadinsky-Cade 1988;Herece 2008).
NE-SW-and east-west-trending folds, thrusts and strike-slip faults occur in the eastern and western part of the bend (Fig. 13). The deformation in the northern part of the bend is mostly accommodated by folding, corresponding to the topographically highest area. The southern flank, parallel to the Murat River, is characterized by a series of thrust faults. The NW and SE flanks of the bend are delimited by strike-slip faults. In the NW, faults related to a continuation of the Palu segment merge with the bend and are transformed into thrust faults or anticlinal axes. The bend is characterized by parallel east -west-trending thrust faults dipping c. 408 to the north. Quaternary activity of the fault is reflected in tilted alluvial-fan deposits localized along fresh scarps.
Up to 1.8-km-long surface ruptures with rightlateral strike-slip were reported from the 22 May 1971 Ms 6.8 Bingöl earthquake (Arpat 1971;

Lake Hazar releasing bend
The releasing bend between the Palu and Pütürge segments generally corresponds to the position of Lake Hazar, which is 216 m deep (Garcia Moreno et al. 2011) and 19.5 × 5.5 km in size. The detailed fault geometry of the EAF as mapped by us around Lake Hazar is shown in Figure 14. The faults beneath the lake are from Garcia Moreno et al. (2011). The Palu segment splays into two sections as it approaches Lake Hazar from the east. The remarkably linear northern splay runs towards the centre of the lake, marked by a narrow trough that is generally located along the flank of the mountain. The northern splay has a prominent dip-slip component and becomes a braided fault array that extends to the southern margin of the lake. The Pütürge segment is made up of two parallel faults that run eastwards into the basin from the southwestern corner of the lake. An array of associated secondary faults appears to splay out towards the lake and these mostly trend parallel to the linear faults. According to Garcia Moreno et al. (2011), beneath the lake the Pütürge Fault continues as a pure strike-slip fault for 5-6 km reaching Kilise Island and then runs beneath the deep basin. A c. 2-km-wide left-stepover or bend of 88 is implied when the strikes of the Pütürge and Palu segments are projected towards the lake.
Based on fault geometries both on land and beneath the lake (Garcia Moreno et al. 2011) east of Kilise Island, the Lake Hazar releasing bend has a minimum width of 2 km and length of 25 km, while between Sogukpınar and Kartaldere the bend increases to a maximum of 33 km long and 4 km wide (Fig. 14). This is larger than comparable features of other sections of the EAF such as the Gölbaşı and Türkoglu releasing jogs.

Yarpuzlu restraining double bend
The bend is located in a highly complex deformation zone where the EAF and BSZ intersect obliquely with the Pütürge and Erkenek segments (Fig. 15). The Pütürge segment is characterized by a single linear fault. Towards the jog the fault is separated from the Erkenek segments by a right-stepover, which involves the bend turning into reverse faults with no single simple direct surface connection. The Erkenek segment joins the bend as a single trace with a slightly concave southwards geometry indicating transpression. In the front of the bend there are two generally east -west trending sub-parallel reverse faults within a 1.5-km-wide zone, defining a sinuous or slightly omega-shaped geometry.
The bend is characterized by regional-scale uplift. The antecedent Hopan River cuts the bend forming a curved canyon (Fig. 15). At the upstream end of the canyon, a larger valley with an alluvial-filled base has developed on the hanging wall of reverse faults that are involved in the bend due to backtilting. There was also a lake called Abdülvahip in the tilted valley floor, now beneath Ç at dam reservoir. The left-lateral curve of 13 + 2 km in the Hopan River valley can be considered as the total offset of the double restraining bend (x and y in Fig. 15).

Gölbaşı releasing stepover
This stepover, corresponding to the Gölbaşı basin, is marked by a 158 change in the general strike direction of the EAF (Fig. 16). The Pazarcık segment delimits the southern margin of the basin as far as Lake Gölbaşı, forming a linear trace and cutting localized alluvial-fan deposits. The segment curves at its eastern end, gains a normal fault component and obliquely bounds Lake Gölbaşı in the west. The Erkenek segment then extends northwards away from Lake Gölbaşı. Westwards, the northern margin of the basin is bounded by relatively short normal fault sets (3-10 km). These are discontinuous, sinuous or slightly curved and dip to the south at an N728E trend within a 3-km-wide zone.
The rhomboidal Gölbaşı basin is divided into eastern and western sub-basins connected by a narrow strait. Three lakes are developed in the basin, namely Gölbaşı, Azaplı and İnekli. From east to west the 15-km-long western sub-basin enlarges to 6 km wide. The formation of the İnekli and Azaplı lakes appears to relate to the transport of alluvial sediments from north to south. The eastern sub-basin, Lake Gölbaşı, is a typical pullapart basin that developed in the recently active leftstepover area. The development of the Gölbaşı basin is believed to be related to the migration of a stepover to form a complex depression with an early phase in the east and a mature phase in the west.

Türkoglu releasing stepover
The EAF between Antakya and Gölbaşı forms a wide concave-southwards bend of length c. 200 km, trending at c. 1558. This delimits the northern and western sides of the Karasu tectonic trough. The Türkoglu stepover is a local structure in the apex of this mega-bend and separates the Pazarcık and Amanos segments of the EAF (Fig. 17). Lake Gavur is a pull-apart basin developed in the stepover, which is infilled by alluvium from the Aksu River.    16. Active fault and Quaternary geological map of the Lake Gölbaşı releasing stepover and its vicinity. The relief base map of the area was produced from a topographic map with a 10 m contour interval. The Gölbaşı stepover was formed between left-stepping Erkenek and Pazarcık segments of the EAF. Abbreviations: ES, Erkenek segment; PS, Pazarcık segment; LG, Lake Gölbaşı; Lİ, Lake İnekli; LA, Lake Azaplı; R, river; (1) Holocene river bed and lake deposits; (2) Holocene fan deposits; (3) undifferentiated terrace deposits; (4) landslide deposits; (5) left-lateral strike-slip fault; (6) normal fault; (7) Southeastern Anatolian Thrust Zone; (8) syncline; (9) anticline. Nowadays Lake Gavur and its neighbouring marshland have been drained into the Aksu River. In the west of the basin discontinuous normal fault arrays vary in width by 2 -6 km, forming a sinuous geometry and a stepped morphology. Fault zones that cut basement rocks generally exhibit limonitic hydrothermal alteration, whereas faults that transect alluvial fans exhibit distinct dip-slip scarp.

Nurhak Fault complexity
Nurhak Mountain (3081 m) is located on the hanging wall of reverse faults within the complexity. The uplifted morphology is characterized by young river incision. The front of the complexity has a board omega-shaped geometry. There is a triple junction created by the intersection of the Ç ardak and Sürgü segments of the SMF system and the Malatya Fault, respectively (Fig. 18). Eastwest-striking segments of the SMF system connect with the complexity forming a double bend with angles of 1308 and 1558 in the east and west, respectively. The Malatya Fault joins the complexity with an angle of 508 from the north. The Ç ardak Fault splays into fault sets that gain a reverse component towards the bend in the Barış region and continue in the fault complexity as reverse faults. Reverse faults also make up the complexity front in the south, characterized by prominent fresh scarps within alluvial fans that are upthrown to the north. Around Nurhak, the east -west trending reverse faults change eastwards to a NE-SW direction and join the Malatya Fault. To the east of the complex, a more linear, dominantly strike-slip fault connects to the Sürgü Fault with a left-stepping bend. In addition, the 27-km-long highly segmented NE -SW-striking and transpressional Doganşehir Fault Zone joins the complexity from the NE.

Göksun releasing bend
This bend forms a 1408 releasing fault jog that connects the Savrun and Ç ardak faults (Fig. 19). The SMF system changes direction from east -west to NE -SW within the bend. The bend separates Berit Mountain from the Göksun plain, representing the northern and southern blocks of the fault, respectively. The plain (15 × 6 km) reflects a releasing bend geometry. The basin plain is c. 1350 m above sea level and is mainly infilled by fluvial sediments and alluvial fans that are tilted towards the fault. The Göksun River that drains the basin is characterized by a centripetal drainage pattern. The river flows to the lowest part of the basin near the apex of the bend before leaving the basin parallel to the Ç ardak Fault (Fig. 19). This area exhibits small ponds that remain in depressions. Holocene fan deposits along the sides of the basin are clearly cut by the Ç ardak Fault. The relatively small size and back-tilted nature of alluvial fans is consistent with normal or oblique faulting on a steep, faulted mountain front. Within the bend area, Berit Mountain exhibits a steep, long faulted slope (c. 750 m above from basin) with an uplifted erosion surface, karstic landforms and mature hanging valleys.

Delihalil releasing bend
This releasing bend (Fig. 20) is a left-stepover between the Yumurtalık and Toprakkale faults, where the trend of the SMF system changes by 158 northwards. Regionally, the Delihalil releasing bend occurs where the Düziçi-Osmaniye, Erzin, Toprakkale, Karataş and Yumurtalık fault segments coincide. The Yumurtalık Fault terminates in lava flows located south of Delihalil volcanic cone. Within the volcanic area, interrelated cones are aligned on a NE-SW-trending extensional fissure. To the east of the cone, basaltic products crop out along the 10-km-long western part of the Toprakkale Fault which exhibits a component of dip-slip. Some other Quaternary volcanic cones appear to be aligned parallel to extensional fissure that are associated with the Toprakkale Fault.
Based on the local fault geometry, the Quaternary basaltic volcanism in the area is thought to relate to the Delihalil bend. However, the eruptive centres are also widespread in the area between the Düziçi and İskenderun faults. This basaltic volcanism is also comparable to the Quaternary volcanism of the Karasu basin, located between the EAF and DSF.

Active faults in Karasu trough
The Karasu valley (Fig. 21) can be interpreted as a releasing bend associated with the linkage of the left-lateral EAF and the DSF, separating two continental plates. The NE-SW-striking trough is 160 km long by 12 -35 km wide and exhibits complex morphotectonic structures. The trough can be classified into northern, mid and southern morphotectonic sections. The northern section encompasses two plains drained by the Aksu River; these are separated by a hilly landscape that is transected by a mature valley trending east -west. The Saglık plain includes a lacustrine pull-apart basin in the NW part of the trough related to the releasing bend. The Narlı plain is located on the hanging wall of a normal fault zone on the NE side of the through. The southern trough is the largest of the three sections and includes the Amik basin, which developed at the triple junction. The central part is a narrow linear hilly range exposing ophiolitic rocks in the mid part, bordered by Quaternary blocky lavas. The Amik transtensional triple junction (20 × 19 km) is  Table 1).

Narlı Fault Zone
This fault zone forms the northernmost tip of the DSF zone and delimits the Karasu tectonic trough both morphologically and structurally, with the development of the Narlı plain (c. 600 m above sea level) (Figs 7 & 21). The zone is characterized by sub-parallel normal faults dipping westwards and separated by relay ramps. The western fault transects Quaternary alluvial deposits and forms prominent scarps up to 10 m high, or delineates the contact between Eocene carbonates and Quaternary alluvium deposits. These scarps indicate Late Quaternary-Holocene activity of the fault.
Late Miocene basalt crops out on the opposing fault blocks. The basalt on the footwall is horizontal and forms a plateau c. 1100 m above sea level. The basalt on the hanging wall is tilted up to 308 to the east together with underlying Eocene limestones and the alluvial infill of the Narlı plain. The morphotectonic features reveal that the total vertical fault offset exceeds 600 m and that the fault is listric at depth. Near Narlı where the fault is exposed in a road-cut, the plane dips at 55-658 to the west with a rake of c. 408, demonstrating right-lateral slip. This could be explained by relative block rotations at the intersection of the plate boundary systems. The Narlı Fault Zone makes a c. 10-km-wide rightstepover with the Yesemek Fault.

Yesemek Fault
This is a left-lateral strike-slip fault that delimits the easterly margin of the Karasu trough between Sakçagöze and Reyhanlı (Figs 7 & 21). The fault comprises two sections separated by a 3-km-wide left-stepover. The southern section is c. 57 km long with a north -south trend and systematic leftlateral offsets of Holocene streams, lineated basalt outcrops, hot springs, trenches and volcanic cones located along the fault. NE of Yalankoz, the fault cuts Quaternary volcanics.
The northern section is 54 km long with a N358E trend and traverses an ophiolitic landscape with  displaced surface features including offset drainage networks and shutter ridges (Fig. 22a). The observed cumulative offset reaches c. 500 m (Fig. 22b). The fault terminates to the north, changing its direction to NE -SW and gaining a normal-fault component to dip eastwards. Travertine is common along the fault and Holocene fault scarps are widespread. The cumulative offsets are 30-40 m, as measured in river channels and incised alluvial fans that probably developed during Last Glacial -Holocene time.
The offsets imply a 1.5-2 mm a 21 slip rate during Late Quaternary-Holocene time. The proposed epicentre of the 1822 event (Ambraseys 1988) is parallel to and between the Amanos and Yesemek faults. The relatively fresh fault-related topography along the Yesemek Fault suggests that the 1822 event may have been generated along the Yesemek Fault.

Reyhanlı Fault
This is a right-lateral strike-slip fault with a component of reverse motion that extends between the Amik triple junction and the Afrin Fault, one of the segments of the DSF zone in Syria (Fig.  21). This is a transfer fault that locally preserves a NW-SE trend. In Turkey, the fault transects Miocene marl and overlying Plio-Quaternary caliche.

Antakya Fault Zone
This is a left-lateral fault zone with a component of eastwards dip-slip which connects to the CA (Fig. 21). The fault zone is separated from the Amanos Fault by the Amik triple junction. In the SW, the fault zone traverses a mountainous terrain creating en echelon faults of length 4-15 km. The up to 5-km-wide fault zone includes sinuous or slightly zigzag fault geometries. More linear faults are dominantly strike slip as observed from slickensides, whereas curved faults exhibit normal components. The faults generally traverse pre-Quaternary rocks but in some places cut Quaternary talus and travertine. For example, a large terrace is formed on the northern fault block around Harbiye.
An elevated erosion surface exists between the Antakya Fault Zone and the Hacıpaşa segment. This surface is deeply incised reflecting strong tectonic uplift that has taken place during the Quaternary. Supporting evidence is provided by fault plane solutions derived from intensive microearthquake activity within the fault zone (generally normal and oblique) (Ergin et al. 2004).

Discussion
Our results suggest that some previous interpretations need to be re-assessed.

Gökdere uplift and Bingöl basin
Some authors have interpreted the Bingöl basin as a pull-apart basin relation to a Genç fault segment of the EAF (Arpat 1971;Arpat & Ş aroglu 1972;Ş aroglu et al. 1987, 1992aBarka & Kadinsky-Cade 1988;Herece 2008). However, we are unable to confirm the existence of this fault. In addition, it has been reported that 1.8-km-long rightlateral strike-slip surface ruptures were formed during the 22nd May 1971 (Ms 6.8) Bingöl earthquake (Arpat 1971;Arpat & Ş aroglu 1972). These authors believed that these ruptures were associated with a conjugate fault zone to the EAF.
At the western margin of the plain south of Bingöl, two c. 5-km-long NW -SE-striking faults are clearly visible in the field and on aerial photos where the 1971 surface rupture occurred. In our view, the presence of a right-lateral surface rupture related to the 1971 event is strong evidence for counter-clockwise rotation within the large restraining Gökdere bend. Similar conjugate left-lateral strike-slip surface ruptures were also observed in the restraining stepovers related to the right-lateral strike-slip faulting on the NAF during the 12th November 1999 Düzce earthquake of Mw 7.2 (Duman et al. 2005).

Maraş triple junction
Some researchers have suggested that the EAF formed the Gavur Gölü pull-apart basin at the Maraş triple junction (around Türkoglu). It then transected the Amanos Mountains, followed by a connection with the fault zone at the northern end of the Gulf of İskenderun (e.g. McKenzie 1976;Gülen et al. 1987;Karig & Kozlu 1990;Perinçek & Ç emen 1990;Westaway & Arger 1996;Westaway 2003). However, our findings on the fault geometry around Türkoglu based on aerial photographs and detailed field surveying do not indicate the existence of any active structure related to a triple junction except for a local stepover at Türkoglu.

Lake Hazar
Using high-resolution seismic profiles, Garcia Moreno et al. (2011) have suggested that: the Lake Hazar pull-apart basin completed its formation 300 000 years ago; the active strand of the EAF cuts across the Lake Hazar basin floor without any stepover or gap; and a 130-km-long surface rupture occurred on the single fault segment that corresponds to the Palu and Pütürge segments during the 1874 earthquake of Ms 7.1. In addition, they did not consider the Lake Hazar jog structure as a segment boundary or appreciate its importance for earthquake hazard assessment.
Where we infer the presence of a bend or stepover, Garcia Moreno et al. (2011) suggest that the deep basin (c. 10 × 4 km) is cut by the main fault, with the basin being bounded by normal faults to the south and the north. These authors believe that there is a subtle releasing bend of 68 between the two main faults. However, there is a seismic line gap of c. 4 km length in the eastern half of the deep basin. Because of this gap it is unclear whether the associated jog is a bend or a stepover. The strike variation on the main fault suggests the existence of a bend structure in the eastern part of the deep basin with the jog representing a releasing stepover.
There are two different views as to whether the surface rupture related to the 1874 earthquake of Ms 7.1 and the 1875 earthquake of Ms 6.7 (Ambraseys 1988) terminates against a segment boundary near Lake Hazar. In the interpretation of Garcia Moreno et al. (2011), there should be a 183-km-long single fault segment of the EAF between the Gökdere and Yarpuzlu restraining jogs. However, the damage due to the 1874 earthquake was centred on the Palu segment and did not extend into the Pütürge segment (Ambraseys 1988;Ambraseys & Jackson 1998). Historical macroseismic data are consistent with the location of the surface ruptures that we observed on the Palu segment. The southerly branch of the Palu segment is also accompanied by surface faulting related to the 1874 event with a vertical offset of 2 m, and dips to the north (Ambraseys 1988;Ambraseys & Jackson 1998;Ç etin et al. 2003). Vertical offset raised the southern coast of the lake by up to c. 2 m, posing an obstacle to the outflow of the Tigris River. Historical records reported by Ambraseys (1988) reveal that during the 1875 event the lake coast rose by 2 m, making a total of 4 m of uplift relative to the outlet to the Tigris valley. These data indicate that the surface faulting associated with the 1875 event overlapped with the 1874 rupture at the SE corner of the lake. The 1875 event could therefore have been generated from faults within the complex releasing bend geometry that is inferred to exist within Lake Hazar.

Linkage between the EAF and other plate boundary faults
The main southern strand of the EAF joins the DSF and CA at the Amik triple junction. However, the northern strand (the SMF system) connects to the KMF zone in Gulf of İskenderun (Fig. 21).
The SMF system extends to the Mediterranean coast via the Karataş and Yumurtalık faults and also connects to the KMF zone. The KMF divides the İskenderun and Adana basins and forms a zone of tectonic uplift between Turkey and northern Cyprus (e.g. Ben Avraham et al. 1995;Robertson et al. 2004;Hall et al. 2005;Aksu et al. 2005a, b). These two left-lateral strike-slip fault zones formed within the pre-existing Neotethyan suture zone during the Late Pliocene, concurrent with the EAF (Ş aroglu et al. 1987, 1992aRobertson et al. 2004;Herece 2008).
The SMF system relates to the zone of continental collision between the AR -AF and Eurasian plates and is located within an accretionary prism, namely the Kyrenia -Misis -Andırın zone (e.g. Robertson & Woodcock 1986;Kelling et al. 1987;Yılmaz et al. 1988;Karig & Kozlu 1990;Yılmaz & Gürer 1996). In places the fault system re-utilizes slip surfaces related to pre-existing faults within the suture zone or the Late Mesozoic accretionary prism. The SMF system was active as thrust faults within the Misis-Andırın complex but then developed into a strike-slip zone during the Pliocene (Robertson et al. 2004). This change was contemporaneous with the initiation of the EAF. The leftlateral strike-slip fault system follows what is in effect an example of indentation tectonics (Muehlberger & Gordon 1987).
The structural linkage between the main strands of the EAF, DSF and CA exhibit complex fault geometries that are related to (1) the Karasu trough where the EAF and DSF overlap (see Fig. 21) and (2) the Amik triple junction between the EAF, DSF and CA.
In different studies the Karasu valley is postulated to be a graben, a rift basin or a pull-apart basin (e.g. Arpat & Ş aroglu 1975;Muehlberger & Gordon 1987;Ş engör et al. 1985;Gülen et al. 1987;Perinçek & Ç emen 1990;Rojay et al. 2001). In contrast, Adıyaman & Chorowicz (2002) interpreted the Karasu depression as a synclinal basin that developed in response to a compressional tectonic regime to the north of the DSF. Karabacak et al. (2010) suggested the existence of an en echelon active fault zone along the western side in the Karasu valley, effectively a transfer zone between the DSF and EAF zones. Westaway (2003Westaway ( , 2004 proposed that the Karasu valley formed at the transpressive stepover on the DSF zone. The Karasu trough is bounded by the Amanos and Yesemek fault segments, which are the southernmost and northernmost tips of the EAF and DSF, respectively. These two left-lateral strike-slip faults overlap each other with left-stepover along the corridor (Fig. 21).
The linear volcanic centres on the fault traces are associated with some fissure-related eruptions. In addition, the Narlı Fault Zone (which bounds the northeastern part of the corridor) reflects the existence of an oblique fault. Some seismic data from Amik plain (Perinçek & Ç emen 1990;Perinçek & Eren 1990) show that, in some areas, normal faults play an important role in the structural evolution of the corridor during the Quaternary. The existence of the normal faults within the corridor is indicative of transtensional processes during the recent structural evolution of the Karasu trough. However, the fault segments of both the DSF and EAF systems locally exhibit a transpressive character because of the existence of right-stepping splays or of en echelon faults, especially at the northern and southern part of the trough (e.g. Westaway 2003Westaway , 2004Gomez et al. 2006). Consequently, our interpretation of the Karasu corridor is as a tectonic trough formed at a regional-scale releasing bend structure between the EAF and DSF systems (Fig. 21).
Some authors interpreted the Amik basin as a pull-apart basin between the DSF zone and the Amanos Fault (e.g. Perinçek & Eren 1990;Ş aroglu et al. 1992a;Karabacak et al. 2010). Perinçek & Eren (1990) suggest that the Amik basin formed in Late Miocene and Late Pliocene extensional phases. The activity of the northern DSF zone in the Amik basin started after the Pliocene. The Amik triple junction exhibits transtensional fault jogs which are located between the Amanos segment of the EAF, the Hacıpaşa segment of the DSF and the Antakya segment of the CA (see Fig. 21). The Antakya Fault appears to join the CA beneath the sea (Hall et al. 2005;Aksu et al. 2005a). The triple junction is a depressed area 20 km long by 19 km wide, where the Amik basin is infilled with Plio-Quaternary sediments.

Slip partitioning along the EAF
The fault geometry is consistent with an accommodation of the lateral motion between the AF, AR and AN within a complex broad zone. Geodetic data (McClusky et al. 2000;Reilinger et al. 2006) indicate that the slip rate of the main strand of the EAF decreases along the Karasu trough where the Amanos segment of the EAF and the Yesemek segment of DSF overlap each other. Farther south, the slip rate is c. 4.5-4.8 mm a 21 (Reilinger et al. 2006). In addition, the lateral slip rate on the eastern part of the CA which connects to the Amik triple junction via the Antakya Fault is 7 mm a 21 as derived from GPS measurements (Reilinger et al. 2006). However, there are no geodetic data along the SMF system, which is suggested in this study to bifurcate from the main EAF to form a northerly strand.
The total geological offset and the related slip rate of the EAF refer to the last c. 3 Ma (Ş aroglu et al. 1987, 1992aWestaway & Arger 1996;Westaway 2003Westaway , 2004Herece 2008). GPS and geologic slip rates are consistent between Karlıova and Ç elikhan where the lateral motion is localized in a narrow zone represented by a single strand of the EAF. The total geologic slip rate was suggested to be c. 8.3 mm a 21 (Herece 2008), again consistent with the geodetic data (Reilinger et al. 2006) for between Karlıova and Ç elikhan. In contrast, there is no clear consistency between the geodetic data and the geologic slip rates along the fault segment located west of Ç elikhan.
The suggested total geological offsets on the Erkenek and Pazarcık segments west of Ç elikhan vary over the range 9-26 km (Erdogan 1975;Yalçın 1979;Perinçek & Kozlu 1984;Westaway & Arger 1996;Ş aroglu et al. 1992a;Westaway 2003;Herece 2008). According to the correlation of geological features, the minimum offsets on the Erkenek segment are 20 and 22 km, respectively (Erdogan 1975;Herece 2008). The geomorphologic offset on the Erkenek segment in the Göksu River valley was suggested to be 13 km by Ş aroglu et al. (1992a), which corresponds to the total offset during the Quaternary with a slip rate of c. 6.5 mm a 21 . Accepting these two offsets, the average slip rate for the Erkenek segment is c. 6.5-7.0 mm a 21 . Slip rates vary from 4.0 to 4.6 mm a 21 on the Pazarcık segment, assuming the validity of left-lateral offsets in ophiolitic units and drainage channels as suggested by Westaway & Arger (1996) and Westaway (2003), respectively. However, Karabacak et al. (2011) suggested a slip rate of c. 9.18 mm a 21 based on palaeoseismological data.
In the south, the EAF and the DSF overlap for c. 160 km in the Karasu trough. The GPS-derived slip rate along the trough between the AR and AF plates is c. 6.8 mm a 21 (Reilinger et al. 2006). Within the through, the lateral movement between the two plates is mainly accommodated by the Amanos Fault of the EAF and the Hatay Fault (our Yesemek Fault) of the DSF (Westaway 2003;Seyrek et al. 2007). Radiometric dating of Quaternary volcanics suggests a slip rate of c. 2.8 mm a 21 on the Amanos Fault (Seyrek et al. 2007). A slip rate of c. 2.68 mm a 21 has been suggested based on the measured 10 km total offset of ophiolites exposed on the southern section of the East Hatay Fault (Westaway 2003). Summing these values gives a total slip rate of 5.57 mm a 21 on the Amanos and Yesemek faults along the Karasu trough (Seyrek et al. 2007). Our findings on the northern section of the Yesemek Fault suggest a slip rate of 1.5 -2.0 mm a 21 , which is coherent with the slip rate partitioning between the Amanos and Yesemek faults as suggested by Seyrek et al. (2007). Palaeoseismological data are still needed to compare long-term slip rates between the offsets and GPS data in detail.
Based on the geological and geomorphological offsets mentioned above, a slip rate of 6.5-7.0 mm a 21 is suggested for the Erkenek and Pazarcık faults between Ç elikhan and Türkoglu, which is similar to the total amount of geodetic slip rate (6.8 mm a 21 ) suggested for the Karasu trough further south (Reilinger et al. 2006). This information suggests that the lateral motion between the AR and AF plates along the Karasu trough is proportionally partitioned by the EAF and DSF within a wide deformation zone.
There are no definitive geodetic data for the SMF system (our name for the northern strand of the EAF). However, the decrease in slip rate to 2-3 mm a 21 , as determined from GPS data from the southern strand of the EAF west of Ç elikhan, could be reflected in a regionally active kinematic structure. A c. 2 mm a 21 slip rate was first suggested for the Yakapınar-Göksun and Sürgü faults by Westaway (2003). Our findings suggest a slip rate of c. 3 mm a 21 for the eastern half of the SMF system. The average 3 mm a 21 slip rate for the western half is partitioned into the Yakapınar-Savrun, Yumurtalık/Karataş and Toprakkale faults. Based on the Holocene geomorphological offsets of the Toprakkale -Yumurtalık/Karataş faults (which were believed to be inactive by Westaway 2003) and the Yakapınar-Savrun fault we suggest partitioned slip rates of c. 2 and 1 mm a 21 , respectively.
The southern and the northern strands of the EAF system accommodate 2/3 and 1/3 of the overall c. 10 mm a 21 slip rate (McClusky et al. 2000;Reilinger et al. 2006) across the EAF between the AR, AF and AN plates in the Ç elikhan-Adana -Antakya region. Comparisons of the fault geometry and the slip data reveal that the EAF is not a simple plate boundary as previously believed (Muehlburger & Gordon 1987;Westaway 2003Westaway , 2004. Although left-lateral motion is localized along a narrow zone east of Ç elikhan, the plate boundary deformation occurs in a broad zone west  Ambraseys (1988), Ambraseys and Jackson (1998) and Tan et al. (2008). The instrumental data are from Aktar et al. (2000), Kalafat et al. (2011) and Ergin et al. (2004). Letters inside boxes refer to the original source for the historical earthquakes. Abbreviations: ST, Shebalin and Tatevossian (1997); KU, Kondorskaya & Ulomov (1999); EG, Guidoboni et al. (1994); AM, Ambraseys (1988); AJ, Ambraseys and Jackson (1998) of Ç elikhan, becoming more complex towards to SSW where the EAF, DSF and CA merge. Along the transtensional Karasu trough north of the Amik triple junction, the slip partitioning between the EAF and DSF is about even.
Based on palaeoseismological data, a recurrence interval of 360 years was suggested for the Palu segment by Ç etin et al. (2003). Based on a slip rate of 11 mm a 21 and an offset of 4.85 m related to the 1874 earthquake, an alternative recurrence interval of 440 years was also suggested by the same authors. We suggest a recurrence interval of 350-400 years for the Palu segment, considering the maximum displacement of 3.5-4.0 m as measured by us related to the 1874 earthquake combined with the GPS-derived slip rate of c. 10 mm a 21 (McClusky et al. 2000;Reilinger et al. 2006). The estimated strain accumulation on the Karlıova and Palu segments for the latest large earthquakes is 1.46 and 1.40 m, respectively.
There are no data for the recurrence interval for a large earthquake on the Pütürge segment. Considering the damage distribution, the 1905 (M 6.8) earthquake (Ambraseys 1988) may have occurred on the Yarpuzlu bend which is located at the western tip of the Pütürge segment. For this reason, the 96-km-long Pütürge segment may be one of several seismic gaps along the main strand of the EAF. The Gökdere restraining bend between Karlıova and Ç elikhan may be another seismic gap in the main fault strand. Some stress transfer is likely to have taken place to the other faults (,15 km) in the bend generated by the 1971 (M 6.8) and 2010 (Mw 6.0) earthquakes.
we assume that there is c. 0.83 m of strain accumulation on this segment since the 1893 event.
The palaeoseismological data for the Pazarcık segment indicate that the 1114 and 1513 earthquakes occurred on this segment with a recurrence interval of 399 years (Meghraoui et al. 2006;Karabacak et al. 2011). The time elapsed for the latest event on the segment, the 1513 earthquake, is 491 years. Summing these, a slip rate of 6.5-7.0 mm a 21 and a recurrence period of 400 -500 years can be suggested for the Pazarcık segment based on palaeoseismological data (Karabacak et al. 2011), taking into account the time elapsed since the last large earthquake. This is one of the most important seismic gaps along the EAF, as suggested by Nalbant et al. (2002) and corresponds to a strain accumulation of c. 3.5 m. The largest expected earthquake and the maximum displacement are M 7.3 and 3.5 m, respectively, based on empirical considerations between fault length and maximum magnitude (Wells & Coppersmith 1994).
Assuming even slip partitioning in the Karasu trough, the Amanos and Yesemek faults may be considered to have recurrence intervals which are twice as long as the Pazarcık segment (i.e. .1000 years). According to historical records, the last two earthquakes that can be related to the Karasu trough are the 521 and 1822 events (Figs 23 & 24). There are no field data from the trough to indicate the source fault segment of the 1822 event. Ambraseys & Jackson (1998) suggested that the magnitude of the event was Ms 7.5 with a surface rupture of 200 km. On the other hand, Seyrek et al. (2007) proposed a co-seismic slip of 2.2 m for the 1822 earthquake, assuming that the earthquake was located along the Amanos Fault and operated with the parameters suggested by Ambraseys & Jackson (1998).
The lengths of the Amanos and Yesemek faults that we observed during our study are not consistent with the above interpretations. However, we accept that we could not obtain any data related to the last event along the Amanos Fault, although we have collected surface rupture data on all of the other segments of the EAF. Fresh fault-related morphology is more apparent along the Yesemek Fault that the Amanos Fault. Pending obtaining detailed palaeoseismological data on both of these fault segments, we suggest that the 1822 earthquake might have occurred on the Yesemek Fault. If so, the last earthquake to have occurred on the Amanos Fault would be the 521 event. The Amanos fault segment would be another important seismic gap in the main strand of the EAF zone. Assuming an average 3 mm a 21 slip rate on this inferred seismic gap, 4.4 m of strain accumulation could have developed since 521. If we assume that the 1822 earthquake was generated along the Amanos Fault, a similar interpretation would be valid for the Yesemek Fault which suggests a high earthquake potential in the Karasu trough. Figure 23a shows seven historical earthquakes of Ms . 6.0 (97,1115,1266,1269,1894,1544) which have occurred during the last 2000 years around the SMF system, making up the northern strand of the EAF. The 1998 Ceyhan earthquake of Mw 6.0 (Aktar et al. 2000) occurred on the Yakapınar Fault. No surface rupture is associated with this earthquake. The proposed locations for the 1544 earthquake of M 6.8 (Tan et al. 2008) are close to the Ç ardak and Sürgü fault segments of the northern strand. The average slip rate on the Sürgü and Ç ardak fault segments is c. 3 mm a 21 . Apart from the 1544 event, no large earthquake has occurred on these two segments for the last 2000 years.
According to the slip partitioning (ratio of 1/3) between the strands of the EAF and recurrence intervals (400-500 years) of the Pazarcık segment, an 800-1000 years (or more) recurrence interval can be proposed for the eastern half of the northern strand of the EAF represented by the Sürgü and Ç ardak faults. The empirical relations between fault length and maximum magnitude suggest that these fault segments have the potential to produce earthquakes of Mw . 7.0. The faults in the Nurhak restraining bend fault complexity can also be considered as a possible source zone for moderatesized earthquakes, as occurred within the Gökdere and Yarpuzlu restraining jogs.
Historical earthquake data for the last 2000 years do not provide any information about the recurrence intervals of large earthquakes on the western half of the SMF, as represented by Savrun, Yumurtalık, Karataş and Toprakkale faults. The available data indicate that these faults have generated earthquakes with magnitudes of Mw 6.0 or larger (Fig.  23b). According to our findings, the slip rates on these faults vary from c. 1 to 2 mm. We therefore recommend detailed palaeoseismological investigations of these fault segments.
On the other hand, seismological data do show that the earthquakes on the Yakapınar and Karataş -Yumurtalık faults in the western half of the SMF system are deep-seated events reaching a depth of 30 km (Aktar et al. 2000;Ergin et al. 2004). In contrast, fault plane solutions for the earthquakes (Ergin et al. 2004) located within the Düziçi -Osmaniye Fault Zone indicates normal dip-slip or oblique-slip faulting and focal depths of , 5 km. The earthquakes on the strike-slip faults with deep hypocentres may re-activate pre-existing fault planes in the Misis -Andırın accretionary prism, part of the Neotethyan suture zone.