The East Anatolian Fault (EAF; Turkish: Doğu Anadolu Fay Hattı) is a major strike‑slip fault system in Turkey, extending roughly 700 km from the eastern to the south‑central part of the country. Tectonically it functions as a transform boundary between the Anatolian sub‑plate and the northward‑moving Arabian plate, accommodating relative motion primarily through lateral displacement rather than subduction. Slip on the EAF is predominately sinistral (left‑lateral), reflecting the differential horizontal movement of the adjacent plates. Together with the North Anatolian Fault, the EAF facilitates the westward lateral extrusion of the Anatolian block as the Arabian plate continues to impinge on Eurasia. The fault trends northeastward, linking the Maraş triple junction at the northern end of the Dead Sea Transform to the Karlıova triple junction where it meets the North Anatolian Fault. North of the principal strand, the Sürgü–Misis Fault System—an important parallel structure—extends approximately 350 km (220 mi) and forms a significant component of the regional fault network.
The discovery history of the East Anatolian Fault (EAF) rests on geomorphic mapping, paleoseismic indicators and seismic observations that together identify a left‑lateral strike‑slip structure with recent activity but an imperfectly resolved extent. Lake Hazar occupies a sag pond formed on the EAF, a localized subsidence basin that attests to strike‑slip–related deformation. Early geomorphological work (1963) traced a fault segment running roughly 70 km southwest from Karlıova toward Bingöl, although that study did not define continuation beyond Bingöl.
Clarence Allen (1969) refined the picture by showing that the North Anatolian Fault terminates abruptly east of Karlıova and that a separate southwest‑striking fault system also ends in this region, creating a structurally complex termination zone. Allen documented linear valleys, sag ponds and Quaternary scarps from Palu to Lake Hazar—including fresh scarps along the lake shore—indicating Holocene or latest Pleistocene movement. From the mapped geometry he noted that an uninterrupted southwest trend would geometrically intersect the left‑lateral Dead Sea Transform, and he interpreted the kinematics of the EAF as sinistral based on the geomorphic evidence.
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Seismic data have reinforced this kinematic interpretation: surface fissures produced by the 22 May 1971 Bingöl earthquake exhibited a dominant left‑lateral offset consistent with the orientations of the mapped valleys and faults. This sinistral strike‑slip behaviour and the southwest trend of the fault system are compatible with a regional regime of north–south plate convergence that is accommodated in part by lateral displacement along the EAF.
An alternative synthesis was proposed by Dan McKenzie (1976), who proposed a much longer (≈550 km) strike‑slip fault extending from the Gulf of Alexandretta to the North Anatolian Fault and interpreted it as the plate boundary between Anatolia and Arabia. McKenzie’s reconstruction differs from Allen’s chiefly in the southern termination and in assigning a primary plate‑boundary role to the fault, a difference that underlines continuing uncertainty about the EAF’s full length and its connections to adjacent transform systems.
Main (Southern) strand
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Field mapping and remote-sensing of the 6 February 2023 earthquake sequence delineated the principal surface rupture on the East Anatolian Fault, conventionally depicted as an orange line marking the principal crustal break. This main strand trends northeast–southwest and constitutes a throughgoing rupture of approximately 580 km, extending from Karlıova in the north to Antakya in the south, entirely within Turkish territory. The length and continuity of this rupture indicate a large-scale release of seismic energy with significant along‑strike stress transfer and broad implications for seismic hazard and impacts across the provinces encompassed by the Karlıova–Antakya corridor.
The Karlıova segment forms the northeasternmost, discrete trace of the East Anatolian Fault, extending roughly 25 km (16 mi) along strike from the regional triple junction to the Göynük area. Its northeast termination is defined by the Göynük restraining bend, a structural step that links Karlıova into the adjacent Ilıca segment and locally alters fault kinematics and the surface expression of deformation.
Numerous geomorphic and hydrothermal indicators document recent surface deformation on the Karlıova trace. Fresh fault scarps, linear valley alignments, pressure ridges and hot springs occur along the segment, and streams exhibit lateral offsets that range from several to hundreds of metres. A measured right-lateral offset of 3.5 m (11 ft), located 1 km southeast of Boncukgöze, is interpreted as a probable surface rupture and may be attributable to the 1866 Bingöl earthquake (Mw 7.1). Although no major rupture on the Karlıova segment has been formally recorded since 1866, the spatial distribution of measurable offsets, geomorphic markers and thermal springs collectively characterize the segment as an actively deforming portion of the East Anatolian Fault system.
The Ilıca segment of the East Anatolian Fault traverses mountainous terrain between the Göynük restraining bend and Ilıca, following a single branch that defines the local surface trace of the structure. The fault corridor is underlain by Paleozoic bedrock locally overlain by volcanic–sedimentary successions of Mio–Pliocene and Quaternary age, reflecting an older basement with younger volcaniclastic and sedimentary cover. In tectonic studies the limb has often been treated not as an independent segment but as part of the Karlıova segment, a grouping that influences interpretations of rupture length and segmentation in regional seismic‑hazard assessments. The Ilıca branch produced documented coseismic surface rupture during the 1971 Bingöl earthquake (Ms 6.8), with approximately 35 km (22 mi) of surface faulting confined to the area northeast of Göynük and not propagating beyond that zone.
Palu segment (Lake Hazar–Palu, 77 km)
The Palu segment forms a continuous geomorphological and tectonic corridor extending roughly 77 km between Lake Hazar and the town of Palu. It functions as an integral portion of the East Anatolian Fault system, linking structural and surface expressions between these two loci.
Instrumental and field records demonstrate that the segment remains seismically active. The northern part ruptured during the Mw 6.1 event of 8 March 2010, when field mapping documented fresh scarps and measurable surface offsets on the order of 2.5–4.0 m. Paleoseismic and historical evidence indicate prior large events: the most recent major earthquake before instrumental times is recorded on 3 May 1874 and is estimated at Mw 7.1, showing the segment’s capacity for high-magnitude rupture. Measurements of coseismic displacement associated with these ruptures include a 2.6 m offset immediately east of Lake Hazar and a mean central-segment slip of 3.5 ± 0.5 m, quantifying typical surface slip magnitudes across the central reach of the Palu segment.
Pütürge segment
The Pütürge segment crosses a rugged mountainous terrain underlain by Paleozoic–Mesozoic metamorphic rocks and by Mesozoic ophiolitic mélange interlayered with clastic sequences. This lithologic assemblage records a complex tectonometamorphic history and the incorporation of obducted oceanic material into the local crustal framework.
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Structural and geomorphic data document substantial cumulative displacement: basement structural measurements and offsets observed along the Euphrates total on the order of 9–22 km (5.6–13.7 mi), evidence of long‑term fault motion that constrains estimates of sustained slip on the segment. Morphologic indicators of late Quaternary activity include Holocene scarps along the trace, although their exact ages have not been established and thus the timing of the most recent surface‑rupturing events remains unresolved.
Historical records identify earthquakes in 1875 and 1905 as plausible candidate surface‑rupturing events on this strand. Instrumental observations during the January 2020 Mw 6.7 earthquake implicated the Pütürge segment in an approximately 45 km (28 mi) surface rupture, demonstrating its capacity to generate multi‑tens‑of‑kilometre ruptures in a single moderate‑to‑large event. Collectively, the lithologic context, cumulative offsets, geomorphic scarps, historical earthquakes, and the 2020 rupture characterize the Pütürge segment as an active, long‑recorded fault capable of producing significant surface‑rupturing earthquakes.
Erkenek segment
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The Erkenek segment, extending between Yarpuzlu and Gölbaşı, records substantial long-term lateral displacement: cumulative offset along this portion of the East Anatolian Fault is on the order of 22.5–26 km (14.0–16.2 mi), indicating sustained slip through the Quaternary and earlier. Geomorphic markers such as stream channels are repeatedly offset by the fault, with channel displacements ranging from a few meters to about 0.5 km (0.31 mi), reflecting multiple episodes of channel diversion and lateral translation over different timescales. Field mapping has also identified fresh-appearing fault scarps on the segment, consistent with surface-rupturing events in the late Pleistocene to Holocene.
Historical and instrumental earthquakes confirm the segment’s capacity for large, surface-rupturing earthquakes. An Ms 7.2 event in 1893 produced a measured ground offset of roughly 4.5 m near Çelikhan, and the 2023 Mw 7.8 earthquake generated approximately 10 km (6.2 mi) of continuous surface rupture on the segment’s northern portion. Together, these observations demonstrate that the Erkenek segment accommodates substantial cumulative slip and remains capable of producing major earthquakes with measurable surface displacement.
Pazarcık segment
The Pazarcık segment of the East Anatolian Fault displays a smooth, regularly undulating planform, resembling a sine curve with concave curvature in both its northern and southern halves. This continuous bend in the surface trace extends along strike between Gölbaşı and Türkoğlu, defining the segment’s mapped limits and structural expression.
Long-term tectonic offset on the strand is substantial, with cumulative displacement estimated at 19–25 km (12–16 mi). Paleoseismological trenching and stratigraphic correlation yield a Holocene slip rate of approximately 9 mm yr−1, indicating sustained recent tectonic activity on the segment. A discrete geomorphic marker about 4 km southeast of Elmalar records a lateral channel offset of 5.0 ± 0.2 m (16.4 ± 0.66 ft); this displacement has been attributed to a seismic event likely dated to 1513.
The Pazarcık segment has been implicated in historical surface-rupturing earthquakes: it is a candidate for rupture during the 1114 event and was one of the fault strands that ruptured in the Mw 7.8 earthquake of 2023, consistent with its measured slip rate and accumulated displacement.
Amanos (Karasu) segment
The Amanos, or Karasu, segment is a ca. 120 km long strand forming the southern portion of the East Anatolian Fault system. Its tectonic affinity is debated: many maps treat it as an integral southern arm of the East Anatolian Fault, whereas other interpretations regard it as a southward continuation of the Dead Sea Fault or as a transitional structure linking the East Anatolian Fault and the Dead Sea Transform. The segment’s southern trace terminates in the Amik Basin, where it intersects the Hacıpaşa Fault (a component of the Dead Sea Transform) and the Cyprus Arc Fault; this nexus constitutes a structural triple junction among the three fault systems.
The Amanos segment has produced major earthquakes in historical times. A significant event in 1872 (estimated Mw ≈ 7.2) is attributed to rupture of its southern portion. More recently, the segment ruptured during the 2023 Mw 7.8 earthquake, and approximately two weeks later a Mw 6.4 aftershock was concentrated at the segment’s southern tip, underscoring its capacity for large, multi‑event rupture behavior and its role in regional strain transfer across the triple junction.
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Northern strand
Near Çelikhan the East Anatolian Fault bifurcates, giving rise to a distinct northern branch formally recognized as the Sürgü–Misis Fault System. This named complex comprises multiple linked segments that together form a coherent tectonic feature within the broader East Anatolian fault network.
Kinematically the system is dominated by sinistral (left‑lateral) strike‑slip motion along its constituent segments, producing segmented but continuous lateral displacement. The mapped trace of the Sürgü–Misis system extends roughly 380 km, linking deformation in the Anatolian interior to structures beneath the coastal zone.
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Continuing southwestward, the northern strand connects beneath the Gulf of Alexandretta with the Kyrenia–Misis Fault Zone, establishing a throughgoing structural corridor from continental Anatolia to the northeastern Mediterranean margin. Functionally, this linkage transmits crustal motion and concentrates seismic strain along a continuous sinistral pathway that integrates inland and offshore fault systems across southern Turkey.
Sürgü segment
The Sürgü segment forms a roughly 37 km-long contiguous structural portion of the East Anatolian Fault, defined at its eastern end by a pronounced geomorphic shutter ridge approximately 17 km long and 1 km wide, and continuing westward for a further ~20 km along the same structural trend. In the western part of the segment the fault splits into two subparallel strands that diverge along strike and then reconverge at Nurhak, producing a clear point of strand integration where displacement is transferred between the branches.
Geomorphic and paleoseismic evidence attest to active late Quaternary faulting on this stretch. A Holocene surface rupture transects a Holocene alluvial fan, demonstrating that at least one substantial surface‑breaking earthquake occurred during the Holocene. However, historical seismicity on the Sürgü segment shows variable rupture behavior: the 1986 Ms 5.8 event did not reach the surface, indicating that sizeable earthquakes on this structure can be either surface‑breaking or blind.
Taken together, the shutter ridge, the twin‑strand geometry with integration at Nurhak, and the fan‑cutting Holocene rupture characterize the Sürgü segment as an actively deforming, segmented fault capable of producing occasional large surface‑rupturing earthquakes while also accommodating events that fail to propagate to the surface. These attributes imply complex slip partitioning and variable rupture propagation, with direct relevance for local seismic hazard assessment.
Çardak segment
The Çardak fault segment, which runs approximately 85 km between Nurhak and Göksun, is internally subdivided by a right stepover that creates two discrete subsections. This geometric discontinuity produces structural segmentation that constrains rupture propagation, focuses slip in particular zones, and modulates the spatial pattern of surface faulting along the segment.
Historical reports of moderate events on Çardak are scarce: prior to 2023 the only documented historical earthquake attributed to this structure occurred in 1544 (estimated magnitude ~6.8), a paucity of data that may reflect either long inter-event recurrence intervals or incomplete archival records. On 6 February 2023, a Mw 7.8 mainshock was followed nine hours later by a Mw 7.6 rupture that propagated across the adjoining Sürgü and Çardak segments. The Mw 7.6 event produced 98 km of continuous surface rupture—exceeding Çardak’s standalone length—and generated extraordinary near-surface offsets of 10.0–12.6 m, among the largest surface displacements recorded for an earthquake. These observations confirm multi-segment rupture capacity in the Nurhak–Göksun corridor and have important implications for surface-fault mapping, interpretation of coseismic displacement patterns, and seismic-hazard assessments for the region.
Savrun segment
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The Savrun segment of the East Anatolian Fault trends northeast–southwest and functions as a structural connector between the western Çardak segment and downstream fault elements. It traverses a restraining bend at Göksun and can be traced southwestward toward Sumbas, where its trace links into downstream structures.
At Çiğşar the fault geometry becomes bifurcated: a right-stepover divides the main trace into two distinct strands, producing a segmented fault pattern with a measurable lateral offset in strand position. The northern strand is approximately 20 km (12 mi) long and is manifested in the landscape by fault scarps 0.5–5 m high; geomorphic markers such as gullies show discrete displacements of about 5 m, indicating recent surface slip. The southern strand extends roughly 41 km (25 mi) and includes Holocene-aged scarps along parts of its length, implying at least localized surface-rupturing or near-surface deformation during the Holocene.
Taken together, the restraining bend at Göksun and the right stepover at Çiğşar create a structurally complex, segmented fault zone with a combined mapped length of about 61 km (37 mi). The spatial distribution and magnitudes of scarps (0.5–5 m) and quantified offsets (~5 m) record Quaternary surface deformation and attest to the segment’s recent tectonic activity.
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Çokak segment
The Çokak segment of the East Anatolian Fault is delineated from the adjacent Savrun segment by a left-lateral stepover that produces a measurable geometric offset and a clear kinematic boundary between segments. The principal fault strand trends roughly northeast–southwest and displays along-strike heterogeneity: its northern tip is dominated by normal-faulting, whereas the remaining strand accommodates predominantly left-lateral (sinistral) strike-slip motion. In the southern half of the zone, strike-slip displacement is not confined to a single trace but is shared with a closely spaced, subparallel left-lateral strand to the west, indicating distributed lateral slip across at least two parallel faults. Geological and geomorphic evidence records about 2.5 km of cumulative lateral offset since the Late Pliocene–Quaternary, attesting to sustained Quaternary displacement and long-term accumulation of strain. The concurrence of a normal-faulting northern termination, dominant sinistral slip on the main strand, a western subparallel fault in the south, and the intersegment left stepover implies mixed kinematics—principally strike-slip with a localized extensional component—and a segmented architecture that governs how crustal strain is partitioned along this portion of the fault system.
Toprakkale segment
The Toprakkale segment is a well-defined tectonic section of the East Anatolian Fault extending approximately 50 km (31 mi) between Boynuyoğunlu and the Delihalil volcano. The southern reach near Toprakkale hosts a cluster of small volcanic cones, indicating localized volcanism spatially associated with the fault zone.
Geomorphically, the segment is characterized by normal fault scarps with measured vertical displacements of 2–5 m (6 ft 7 in–16 ft 5 in); these scarps transect Quaternary basalt flows, demonstrating tectonic activity during the late Quaternary against relatively young volcanic rock. A 12 km (7.5 mi) portion of the fault coincides with a valley carved by the Ceyhan River, where offsets of Holocene stream channels by about 20–30 m (66–98 ft) document recent lateral displacement and ongoing deformation of the landscape.
Düziçi–İskenderun segment
The Düziçi–İskenderun segment is characterized by a NW‑trending array of normal faults, reflecting an extensional tectonic regime in which hanging‑wall blocks have subsided relative to footwalls and dip‑slip (vertical) motion predominates. Spatially, this fault set lies east of the Toprakkale segment and forms the western margin of the Amanos Mountains; consequently, faulting here governs mountain‑front morphology, escarpment development, and the abrupt transition from the high‑relief Amanos ranges to lower terrain to the west. Measured cumulative vertical displacement at Erzin of about 80–90 m (260–300 ft) attests to prolonged normal‑fault activity and has direct implications for landscape evolution, stratigraphic offset, and seismic hazard in the area. Collectively, the fault geometry, position relative to Toprakkale, mountain‑bordering role, and substantial offset at Erzin depict a localized zone of extension that contributes to regional topographic and structural segmentation.
The Yakapınar segment of the East Anatolian Fault extends southward from mountainous terrain into the Ceyhan alluvial plain, marking a distinct geomorphic transition from high-relief uplands to low-relief, sediment-filled lowlands along its trace. Structurally the segment trends northeast–southwest and accommodates predominantly horizontal sinistral (left‑lateral) strike‑slip motion, consistent with lateral displacement observed along the fault trace.
Seismically, Yakapınar is a confirmed source of moderate-to-strong earthquakes: it produced the Mw 6.2 Adana–Ceyhan event of 1998, and both historical and paleoseismic records link earlier shocks of approximately Mw 6.0 (1945) and Mw 6.3 (1266) to this segment, indicating recurrence of ~Mw 6 ruptures on multi‑century timescales. Because the fault cuts from rugged highlands into a densely sedimented plain and lies close to the Adana–Ceyhan population centers, its future ruptures may display variable surface expression (attenuated or masked in thick alluvium), site‑dependent amplification in the plain, and the potential for direct impacts on urban and agricultural areas.
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Yumurtalık segment
The Yumurtalık segment forms a distinct coastal reach of the East Anatolian Fault system that runs roughly east–west immediately inland of the northern shore of the Gulf of Alexandretta. It is spatially partitioned into two contiguous subsegments—an eastern portion about 16.5 km (10.3 mi) long and a western portion about 24.5 km (15.2 mi) long—yielding a total shoreline extent of approximately 41.0 km (25.5 mi). Its along-coast orientation and segmentation imply structural control on local shoreline morphology and differential coastal processes between the two units. Treating the eastern and western parts as separate analytical domains aids geomorphological interpretation, coastal-hazard assessment, infrastructure siting, and planning for the distribution of natural and human systems along the gulf’s northern littoral.
The Karataş segment is a significant fault section with a horizontal extent of 64 km (40 mi). It lies north of the Yumurtalık segment and runs subparallel to it, sharing a similar strike while being laterally offset. This north–south aligned geometry implies potential structural continuity or segmentation along a common regional trend, a characteristic that influences mapping, interpretation of connectivity, and assessments of along‑strike interaction and seismic behavior. No absolute coordinates or elevations are provided in the description; therefore precise geographic placement of the Karataş segment must rely on detailed maps or geospatial data referenced to the Yumurtalık segment and the broader regional fault network.
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Seismic activity along the East Anatolian Fault (EAF) demonstrates repeated high‑magnitude ruptures from the late 18th to the early 20th century, with a sequence of major earthquakes documented between 1789 and 1905 (notably M ≈7.0–7.2 events in 1789, 1795, 1872, 1874, 1875, 1893 and 1905). These historical shocks attest to the fault system’s capacity to generate destructive ground shaking; the 1893 Ms ≈7.1 event alone caused more than 800 fatalities, illustrating both the severity of shaking potential and the historical exposure of settlements. Earlier rupture of a segment adjacent to the Karlıova triple junction (reported in 1866, Ms ≈7.2) highlights the tectonic significance of this junction as a locus where fault interactions and rupture propagation exert a regional influence on seismic behaviour.
Instrumental‑era earthquakes provide direct evidence of surface‑breaking slip and complex fault interactions on or near the EAF. Surface rupture was recorded following the 1971 Bingöl earthquake, confirming that seismic slip on the EAF can reach the surface and produce lasting geomorphic signatures. Since 1998 the region has experienced a sustained cluster of damaging earthquakes (including the 1998 Adana–Ceyhan event, 2003 Bingöl, 2010 and 2020 Elâzığ shocks, and the 2023 Turkey–Syria sequence), indicating ongoing active deformation and persistent seismic hazard. Notably, the 2003 Bingöl shock ruptured a nearby conjugate strike‑slip fault oriented approximately perpendicular to the EAF, underscoring that strain may be taken up by adjacent or cross‑cutting structures rather than exclusively by the main fault trace. The 2023 Turkey–Syria earthquakes produced exceptionally long, continuous surface rupture—reported across distances approaching 400 km—demonstrating the EAF’s potential for very large, single‑episode ruptures and the wide geographic extent of attendant ground deformation.