It’s approximately one month on from 6th February 2023 when a 7.8 magnitude earthquake struck on the south western end of the East Anatolian Fault Zone at 01:18 UTC (04:18 local time) 32.4km west northwest of the town of Gaziantep. This, followed by large aftershocks, including a very shallow 7.5 magnitude earthquake to the north of the first quake, caused catastrophic damage in central and southern Turkey, and northern and western Syria. The 7.5 earthquake signalled the rupturing of a second fault zone, the Sürgü-Misis Fault. The final fatality number is not yet available but, at the time of writing, fatalities exceeded 50,000, with hundreds of thousands injured and millions displaced. Our thoughts are with the victims, including those facing a long road to recovery.
We have taken a look at the earthquakes surrounding the Anatolian Plate from the start of January 2023 to 1st March 2023.
The Anatolian Plate lies between the Eurasian Plate, Arabian Plate and African Plate. The African Plate is moving at a rate of 2.15cm per year in a north easterly direction, the Eurasian Plate is moving south, relative to the African Plate, at a rate of 7-14mm per year, the Arabian Plate is moving northward at a rate of 15-20mm per year and the Anatolian Plate is moving south west at the rate of 21mm per year. The relative motions are accommodated by the North Anatolian Fault, East Anatolian Fault, Bitlis – Zagros Fold and Thrust Belt and Dead Sea Transform Fault System.
The East Anatolian Fault is a 500km long fault zone which marks the plate boundary between the Anatolian and Arabian Plates; the boundary is a transform one with left lateral strike slip seismic activity and a slip rate of 10mm per year. The Anatolian Plate is pushed westward by the Arabian Plate moving northwards towards the Eurasian Plate.
The East Anatolian Fault is a single fault between Karliova and Çelikhan. After Çelikhan the fault zone splits into north and south strand, both of which include multiple faults. The Sürgü-Misis Fault makes up the northern strand; it is a 380km long stretching between Çelikhan and Karataş; the eastern parts of the east-west section are made up of the Çardak and Sürgü faults; the sytem changes direction at the Göksun bend dividing into seven north east trending fault systems – the Karataş, Yumurtalık, Toprakkale, Savrun, Misis, Çokak and Düziçi-İskenderun faults. The Sürgü-Misis Fault system connects to the Cyprus Arc via the Misis-Kyrenia fault system. The southern strand of the East Anatolian Fault is less certain; the East Anatolian Fault may extend to the north of Cyprus; and, the NNE trending Türkoğlu-Amik section (the Karasu Fault Zone) may be a separate fault, linking the Dead Sea Transform to the East Anatolian Fault. The Karasu Rift has had Quaternary volcanic activity on northern part and sides of the rift between Kirikhan, Reyhanli and Fevzipaşa in an area 94km long and 12-25km wide.
The North Anatolian Fault, another strike slip fault, accommodates the relative motion between the Anatolian Plate and the Eurasian Plate. The North Anatolian Fault and the East Anatolian Fault meet the Bitlis – Zagros Fold and Thrust Belt, where the Arabian Plate subducts under the Eurasian Plate, at the Karliova Triple Junction.
Not very far to the west, the African Plate is subducting under the Anatolian Plate at the Cyrpus Arc. The Dead Sea Transform Fault System to the south marks the transform boundary between the Arabian and African Plates. The East Anatolian Fault meets the Dead Sea Transform Fault System at the Maras Triple Junction.
We initially plotted the earthquakes from 1 January 2023 to 25 February 2023 for the area 34.47361°N, 25.22222°E to 42.25833°N, 44.45056°E. We then looked at 35.3122°N, 32.50944°E to 41.21667°N, 42.70056°E, focussing on the East Anatolian Fault. The results are shown in the following videos and earthquake density plot.
The geodensity plot shows that most activity occurred on the Sürgü-Misis Fault to the west and east of the 7.5M earthquake.
Most of the faults within the East Anatolian Fault Zone seem to have moved in the period we looked at. However, the scale of our plots may be misleading. Our plots do show a tenuous link between the East Anatolian Fault and the Cyprus Arc. There was some activity on the Arc preceding the 7.8 earthquake. After shocks have migrated through the fault system towards the Arc. There is no obvious link with the Dead Sea Transform Fault in the time period selected but geologically-speaking that is a very short period.
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Sources & Further Reading
Raw earthquake data was downloaded from EMSC, https://www.emsc-csem.org
“Paleoseismology of the western Sürgü–Misis fault system: East Anatolian Fault, Turkey”, Tamer Y. Duman, Hasan Elmacı, Selim Özalp, Akın Kürçer, Meryem Kara, Ersin Özdemir, Ayhan Yavuzoğlu & Çağıl Uygun Güldoğan, Mediterranean Geoscience Reviews volume 2, pages411–437 (2020) https://link.springer.com/article/10.1007/s42990-020-00041-6