Eastern Anatolia Fault System

Eastern Anatolia Fault System
Name	Eastern Anatolia Fault System
Location	Eastern Anatolia, Turkey
Type	Strike-slip fault system
Length	~700 km
Plate	Anatolian Plate, Arabian Plate, Eurasian Plate
Status	Active
Earthquakes	2020 Elazığ earthquake, 2023 Kahramanmaraş earthquakes

Eastern Anatolia Fault System

The Eastern Anatolia Fault System is an active, predominantly right-lateral strike-slip fault system in eastern Turkey that accommodates relative motion between the Anatolian Plate, the Arabian Plate, and the Eurasian Plate. Its complexity, segmentation, and interaction with nearby structures such as the North Anatolian Fault, the East Anatolian Fault, and the Bitlis-Zagros Thrust Zone make it a key locus for regional deformation studies and seismic hazard assessment for cities like Diyarbakır, Erzurum, and Malatya.

Overview

The fault system traverses provinces including Bingöl Province, Elazığ Province, and Muş Province and links broader tectonic provinces such as the Anatolian Plateau and the Iranian Plateau. It forms part of the diffuse plate boundary between the Arabian Plate and Eurasian Plate and interacts with major structures like the Dead Sea Transform and the East Anatolian Fault. Historical campaigns by institutions including the General Directorate of Mineral Research and Exploration (MTA), Bogazici University Earthquake Research, and international teams from USGS, ETH Zurich, and GFZ Potsdam have mapped its geometry and paleoseismic history.

Geology and Tectonic Setting

Geologically, the region comprises ophiolitic mélanges, Mesozoic limestones, Neogene volcanics of the Tauride Belt and the Bitlis Massif, and Quaternary sediments deposited in intermontane basins like the Tuz Golu analogue basins. The system accommodates right-lateral slip resulting from the westward escape of the Anatolian Plate driven by continental collision along the Zagros Fold and Thrust Belt and the ongoing convergence of the Arabian Plate with the Eurasian Plate. Crustal shortening is partitioned between strike-slip motion on the system and thrusting on nearby nappes such as the Suture Zone complexes and the Southeastern Taurus Thrusts.

Fault Geometry and Segmentation

The Eastern Anatolia Fault System comprises several subparallel strands, conjugate faults, stepovers, and transfer zones that link major fault segments near cities like Bingöl, Karlıova, and Palu. Principal segments demonstrate variable slip rates inferred from geodetic campaigns by GPS networks coordinated by AFAD and international partners; rates typically range from a few millimeters to several millimeters per year. Structural geometries include flower structures, pull-apart basins, and restraining bends that correspond with surface ruptures documented in paleoseismic trenches excavated by teams from Istanbul Technical University and Hacettepe University.

Seismicity and Historical Earthquakes

The system has generated destructive earthquakes recorded in Ottoman archives and modern instrumental catalogs maintained by KOERI and the International Seismological Centre. Notable events affecting the broader eastern Turkey region include the 1971 Bingöl earthquake, the 2010 Elazığ earthquake, and the 2020 Elazığ earthquake sequence; these events illustrate multi-segment ruptures and complex aftershock distributions analyzed alongside global catalogs from USGS and EMSC. Paleoseismic evidence links multiple large ruptures to Holocene recurrence intervals, and seismic moment release has been quantified using approaches employed by Harvard CMT and regional inversions.

Monitoring and Hazard Assessment

Continuous and campaign GNSS and InSAR observations from agencies like ESA, JAXA, and national networks provide constraints on strain accumulation and slip deficit along fault segments. Seismic monitoring is provided by arrays operated by KOERI, AFAD, and international collaborations including the International Continental Scientific Drilling Program for paleoseismic coring. Probabilistic seismic hazard assessments for provincial capitals use input from geological slip rates, paleoseismic chronologies, and ground-motion models developed by consortia such as CEGA and research groups at METU.

Geotechnical and Societal Impacts

Surface ruptures, ground shaking, liquefaction, and slope failures along valleys like the Euphrates headwaters and tributaries have repeatedly affected infrastructure including dams, pipelines, and historic built heritage in cities such as Diyarbakır and Malatya. Post-earthquake response and reconstruction efforts have involved national agencies like AFAD, the Ministry of Environment and Urbanization (Turkey), and international NGOs including IFRC and UNDP. Urban vulnerability studies by Istanbul Metropolitan Municipality researchers and engineering teams at Middle East Technical University highlight the interactions between local site effects, construction typologies, and earthquake-resistant design codes.

Research and Modeling Approaches

Research employs multidisciplinary methods: high-resolution paleoseismology, finite-fault rupture modeling using software from groups like USGS and GFZ, dynamic rupture simulations informed by laboratory-derived friction laws from institutions such as SCEC collaborators, and probabilistic seismic hazard models integrating geodesy, seismicity, and geology. Remote sensing advances—using platforms from Landsat, Sentinel-1, and commercial radar providers—combined with machine-learning classification of fault traces by teams at ETH Zurich and NASA enable refined segmentation maps and scenario ruptures for emergency planning by municipal and national authorities.

Category:Seismic faults of Turkey Category:Geology of Turkey