The East Anatolian Fault () is a ~700 km long major strike-slip fault zone running from eastern to south-central Turkey. It forms the transform type tectonic boundary between the Anatolian Plate and the northward-moving Arabian Plate. The difference in the relative motions of the two plates is manifest in the left lateral motion along the fault. The East and North Anatolian faults together accommodate the westward motion of the Anatolian Plate as it is squeezed out by the ongoing collision with the Eurasian Plate.
The East Anatolian Fault runs in a northeasterly direction, starting from the Maras Triple Junction at the northern end of the Dead Sea Transform, and ending at the Karlıova Triple Junction where it meets the North Anatolian Fault.
Discovery
In 1963, geologists published descriptions about a fault structure near Karlıova where the North Anatolian Fault terminates. In their findings, based on geomorphology, they described a fault extending over southwest from Karlıova to Bingöl. The fault to its southwest was not described. Geologist Clarence Allen explained in his 1969 journal regarding the abrupt termination of the North Anatolian Fault east of Karlıova; that a southwest-striking fault also terminated within the same area. He identified fault-related features such as linear valleys, sag ponds and scarps from Palu to Lake Hazar; fault scarps of the Quaternary age was discovered along Lake Hazar's shores. He calculated that this fault structure would intersect the left-lateral Dead Sea Transform if it continued along its southwest trend and suspected it also had a left-lateral slip sense.
Significant attention to this structure arose following an earthquake in Bingöl on 22 May 1971. Ground cracks associated with the earthquake exhibited a dominant left-lateral component which aligned with the trend of valleys associated with the fault. The discovery supported the theory of a mainly left-lateral mechanism for the East Anatolian Fault. This mechanism and trend is also consistent with north–south convergence acting as the predominant tectonic regieme.
In 1976, Dan McKenzie described the fault in the journal Earth and Planetary Science Letters; a strike-slip fault extending from the Gulf of Alexandretta to the North Anatolian Fault. The description of its southern end contradicts that of Allen. McKenzie also stated the fault represented a boundary between the Anatolian and Arabian plates.
Main (Southern) strand
The northeast–southwest trending main strand runs for from Karlıova in the north to Antakya in the south.
Karlıova segment
The Karlıova segment represents the northeasternmost trace of the East Anatolian Fault and extends from the triple junction to Göynük. Its morphology is charactierized by young scarps; streams offset from several to hundreds of meters; pressure ridges; linear valleys and hot springs. A offset located southeast of Boncukgöze could be associated with the 1866 Bingöl earthquake ( 7.1) surface rupture. This segment has not experienced a major earthquake since 1866. The segment terminates at the Göynük restraining bend connecting the Ilıca segment.
Ilıca segment
This segment runs through mountainous terrain from the Göynük restraining bend to Ilıca along a single branch. It traverses through Palaeozoic strata and volcanic-sedimentary strata from the Mio-Pliocene and Quaternary. Previous studies of the East Anatolian Fault consider it part of the Karlıova segment rather than an independent segment. The 1971 Bingöl earthquake ( 6.8) produced of surface faulting on this segment, but did not extend beyond northeast of Göynük.
Palu segment
This segment extends between Lake Hazar and Palu for . The northern part of the Palu segment was associated with a 6.1 earthquake on 8 March 2010. Young scarps and offsets measuring were observed. The last major earthquake occurred on 3 May 1874, estimated at 7.1. East of Lake Hazar, a offset was reported; the average offset associated with the event along the cental part was .
Pütürge segment
The area where the Pütürge segment runs through is mountainous and characterized by Paleozoic-Mesozoic metamorphic and Mesozoic ophiolite mélange and clastic rocks. Measurements of basement rocks and offsets along the Euphrates revealed geologic offsets of . Although there are Holocene scarps, the precise date when they formed is unknown. Earthquakes in 1875 and 1905 may have occurred on the Pütürge segment. This segment was associated with a ~ rupture during the January 2020 6.7 earthquake.