Recovery Underway Following Damaging 24 January 2020 Elazığ Earthquake in Eastern Turkey

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Haluk Eyidoğan, Ph.D., Professor of Seismology, Istanbul Technical University
Tiegan Hobbs, Ph.D., Postdoctoral Seismic Risk Scientist, Temblor (@THobbsGeo)

A destructive magnitude-6.8 earthquake in Turkey leaves thousands homeless. Preceded by foreshocks in late December, this quake may fill a seismic gap. Questions remain about the southernmost segment of the fault.

Citation: Haluk Eyidoğan and Tiegan E. Hobbs (2020), Recovery Underway Following Damaging 24 January 2020 Elazığ Earthquake in Eastern Turkey, Temblor, http://doi.org/10.32858/temblor.070

Eleven days ago, on January 24th, 2020 at 8:55PM local time (17:55 UTC), a magnitude-6.8 earthquake occurred at a depth of approximately 8 km in the Doğanyol district of Elazığ, eastern Turkey — a region famed for its vineyards, growing an endemic type of grape called the “öküzgözü” which means “bull’s eye”. Tragically, as of February 3rd, 2020, the death toll stands at 41 people, with 1607 people reported injured in Elazığ, Malatya and Diyarbakır [1]. Due to the quick response of local search and rescue, however, 45 people were rescued from collapsed buildings, of which 5 still remain in intensive care. Over 1500 of those reporting to the hopsital for injuries have been released, meanwhile the Turkish Red Crescent (Türk Kızılay) and the Disaster and Emergency Management Presidency (AFAD) are supplying emergency provisions to those in need [1,2]. There are an estimated 10,000 people homeless at this time, sheltering in containers, tents, and public refuge sites in schools, sports facilities, and dorms [2].

A photo taken near the epicenter of the January 24, 2020, earthquake prior to the event shows the beautiful countryside. Credit: Ayhan Oğuzalp via Google Maps.

Strong Shaking Continues
During the four days following the magnitude-6.8 mainshock, seismologists recorded 1040 aftershocks with magnitudes between 1 and 5.1. Aftershocks spread along a 50 kilometer stretch of the Eastern Anatolian Fault between Sivrice to Pütürge, spreading outward from the 30 kilometer section of fault that ruptured on January 24, 2020.

Satellite observations of the earthquake region show displacements of at least 60 centimeters (23 inches) along the central portion of the Pütürge segment of the East Anatolian fault. Credit: Sotiris Valkaniotis and the ESA.

Foreshock Activity Preceded the 24 January 2020 Mainshock
Since the mainshock, scientists at Istanbul Technical University analyzed seismic data from the area and discovered foreshock activity that started with a magnitude 4.9 earthquake in the area on December 22, 2019 — 33 days before the mainshock. Foreshock activity subsequently decreased until January 22, 2020. On January 24, 2020, an earthquake of magnitude-6.8 occurred around Doğanyol-Sivrice settlements.

Foreshocks, mainshock, and aftershocks of the January 24th earthquake in map view (top) and by date (bottom). Credit: Haluk Eyidoğan for Temblor.

Recovery Underway As Thousands Remain Homeless
Teams of technical personnel have so far surveyed over 30,000 buildings, and have confirmed that 547 collapsed as a result of shaking. An additional 6270 buildings were severely damaged and 962 were moderately damaged [2]. Authorities are recommending immediate demolition of another 180 buildings that remain hazardous.

The towns hit hardest by the event, Elaziğ and Malatya, have a combined population of approximately 900,000 people, a number exceeding that of the city of San Francisco, California. Residents of these areas are dealing with not only the loss and/or damage to buildings, but the interruption of businesses and the psychological trauma such a natural disaster can inflict. To assist those affected, Türk Kızılay and AFAD has sent in 251 psychosocial support workers to go door to door in the region [2].

Collision of Tectonic Plates Tearing Turkey Apart
What caused this damaging earthquake? The Eastern Mediterranean displays a complex geological structure as a result of the ongoing movement between the Eurasian, African, Arabian, and Anatolian Plates. Many large earthquakes have occurred along faults within the Anatolian Plate as a result of this motion. Two major faults contribute the majority of the seismic hazard in the region: the North Anatolian Fault Zone (NAFZ) and the Eastern Anatolian Fault Zone (EAFZ).

The complex geometry of faults in eastern Turkey is caused by the northward motion of the Arabian Plate towards the Eurasian Plate, with the Anatolian Plate caught in between. The Elaziğ earthquake occurred along the Eastern Anatolian Fault Zone (EAFZ). Nearby, the Northern Anatolian Fault Zone (NAFZ) experienced a series of earthquakes which progressively ruptured along most of its length in the 20th century [3]. Credit: Figure 1 from Bulut et al., 2012 [reference 4], edited for Temblor.

Between the Eurasian and Arabian plates, the Anatolian Plate is being squeezed to the west along the left-lateral (meaning the other side of the fault is always moving to the viewer’s left) EAFZ and the right-lateral (the other side moves to the viewer’s right) NAFZ. These two faults accommodate almost all of the tectonic forces in the region, with the EAFZ taking up one-third to two-thirds of this motion (25-35 milimeters/year) along its 580 kilometer (360 mile) length [5,6]. The January 24, 2020 earthquake occurred around the Sincik-Sivrice segment of the EAFZ, where magnitude-6.7 and 6.8 earthquakes previously occurred in 1875 and 1905, respectively [7,8].

Active faults in eastern Turkey. The blue circles show magnitude-6.0 earthquakes that have occurred during the instrumental period along the Eastern Anatolian Fault. Credit: Haluk Eyidoğan for Temblor.

Seismic Gaps on the Eastern Anatolian Fault
Since the year 1900, the northern section of the Eastern Anatolian Fault has experienced several strong earthquakes. Although pre-1900 earthquakes occurred along on the entire EAFZ, the southern half remained relatively quiet since 1908. This created what scientists call a seismic gap: a portion of a fault which has gone without an earthquake for a longer period of time than would be expected. The recent January 24th event in Elazığ [8] has filled a portion of this gap in the south-central portion of the fault. Of particular interest now is the southernmost segment, between Pütürge and Kahramanmaraş, which most recently ruptured over 500 years ago in the year 1513 [reference 7,8]. Scientists at the Istanbul Technical University have now turned their focus to discerning when this region will likewise reactivate to fill the remaining gap.

References
[1] Disaster and Emergency Management Presidency Situation Report on January 26th, 2020. https://en.afad.gov.tr/press-release-17–response-and-rehabilitation-continues-in-the-aftermath-of-earthquake-in-elazig-and-malatya
[2] Disaster and Emergency Management Presidency Situation Report on January 30th, 2020. https://en.afad.gov.tr/press-release-rehabilitation-efforts-in-elazig-and-malatya-quake-zones-continue
[3] Ross S. Stein, Aykut A. Barka, James H. Dieterich, Progressive failure on the North Anatolian fault since 1939 by earthquake stress triggering, Geophysical Journal International, Volume 128, Issue 3, March 1997, Pages 594–604, https://doi.org/10.1111/j.1365-246X.1997.tb05321.x
[4] Bulut, F., Bohnhoff, M., Eken, T., Janssen, C., Kılıç, T., & Dresen, G. (2012). The East Anatolian Fault Zone: Seismotectonic setting and spatiotemporal characteristics of seismicity based on precise earthquake locations. Journal of Geophysical Research: Solid Earth, 117(B7).
[5] Duman, T.Y. & Emre, Ö., 2013. The East Anatolian Fault: geometry, segmentation and jog characteristics Geological Society, London, Special Publications, 372, 495-529.
[6] Taymaz, T., Eyidoğan, H. & Jackson, J., 1991. Source Parameters of Large Earthquakes in The East Anatolian Fault Zone (Turkey), Geophysical Journal International, Volume 106, Issue 3, September 1991, Pages 537-550.
[7] Özer, Ç., Çakıcı, H. & Kocadağıstan, E., 2020. 24 January 2020 (20:55 TS) Mw6.8 Elazığ-Doğanyol, Eastern Turkey Earthquake, Evaluation Report, Atatürk University Earthquake Research Center, 26.01.2020 Erzurum ,20 pages (in Turkish).
[8] Nalbant, S.S, McCloskey, J., Steacy, S. & Aykut A. Barka, A. A., 2002. Stress accumulation and increased seismic risk in eastern Turkey Earth and Planetary Science Letters 195 (2002) 29-298.

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