Pure and Applied Geophysics

, Volume 170, Issue 3, pp 409–431 | Cite as

Geophysical Images of the North Anatolian Fault Zone in the Erzincan Basin, Eastern Turkey, and their Tectonic Implications

  • Ümİt Avşar
  • Erşan Türkoğlu
  • Martyn Unsworth
  • İlyas Çağlar
  • Bülent Kaypak


The collision between the Arabian and Eurasian plates in eastern Turkey causes the Anatolian block to move westward. The North Anatolian Fault (NAF) is a major strike-slip fault that forms the northern boundary of the Anatolian block, and the Erzincan Basin is the largest sedimentary basin on the NAF. In the last century, two large earthquakes have ruptured the NAF within the Erzincan Basin and caused major damage (M s = 8.0 in 1939 and M s = 6.8 in 1992). The seismic hazard in Erzincan from future earthquakes on the NAF is significant because the unconsolidated sedimentary basin can amplify the ground motion during an earthquake. The amount of amplification depends on the thickness and geometry of the basin. Geophysical constraints can be used to image basin depth and predict the amount of seismic amplification. In this study, the basin geometry and fault zone structure were investigated using broadband magnetotelluric (MT) data collected on two profiles crossing the Erzincan Basin. A total of 24 broadband MT stations were acquired with 1–2 km spacing in 2005. Inversion of the MT data with 1D, 2D and 3D algorithms showed that the maximum thickness of the unconsolidated sediments is ~3 km in the Erzincan Basin. The MT resistivity models show that the northern flanks of the basin have a steeper dip than the southern flanks, and the basin deepens towards the east where it has a depth of 3.5 km. The MT models also show that the structure of the NAF may vary from east to west along the Erzincan Basin.


Magnetotellurics electrical resistivity fault zone conductor Erzincan Basin Eastern Turkey 



This research was funded by grants from NSERC and the Alberta Ingenuity Fund to Martyn Unsworth. It was also supported by a grant to İlyas Çağlar from the Scientific and Research Council of Turkey (TUBITAK-CAYDAG 105Y022). Phoenix Geophysics (Toronto) is thanked for the loan of a broadband MT system. Alan Jones and Gary McNeice are thanked for the use of their tensor decomposition code. Ümit Avşar thanks the Tinçel cultural foundation for funding his research visit to the University of Alberta. We thank Eylem Türkoğlu, Bülent Tank of Boğaziçi University, Ahmet Şener and Tunç Demir of Istanbul Technical University for assistance during data collection. We also thank Erzincan Sugar Factory for assistance and accommodation. Lastly, we would like to thank two anonymous reviewers for their helpful comments. Topography maps were created using the generic mapping tools (GMT) software of Wessel and Smith, (1991).

Supplementary material

24_2012_521_MOESM1_ESM.tif (7.8 mb)
Fig. A1. One-dimensional layered inversion for the central stations on the West and East Profiles. The left panel shows models obtained by unconstrained 1D inversion. Models in the right panel were obtained by fixing the resistivity of the resistive layer to 500 Ωm. Straight lines and curves are 1D and 2D inversion results, respectively, (Türkoğlu, 2009). Supplementary material 1 (TIFF 7961 kb)
24_2012_521_MOESM2_ESM.tif (20.8 mb)
Fig. A2. Apparent resistivity, phase and tipper curves from 2D inversion with τ = 10 and α = 7 for stations used in 1D inversion. Error floors of 20 % and 10 % were applied to the resistivity and phase data, respectively. The error floor for the tipper data was set to 0.02. Symbols and solid lines indicate the observed data (rotated data) and inversion model responses, respectively. The phases are shown in the first quadrant. Supplementary material 2 (TIFF 21333 kb)
24_2012_521_MOESM3_ESM.tif (24.1 mb)
Fig. A3. Pseudosections of residuals of apparent resistivity, phase and tipper data for the inversion models shown in Fig. 10 for the West and East Profiles, respectively. Supplementary material 3 (TIFF 24701 kb)
24_2012_521_MOESM4_ESM.tif (32.4 mb)
Fig. A4. Z xx , Z yy and Z xy , Z yx apparent resistivity and phase curves for some stations in the Erzincan Basin. Solid lines illustrate responses from 3D inversion. Supplementary material 4 (TIFF 33214 kb)


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Copyright information

© Springer Basel AG 2012

Authors and Affiliations

  • Ümİt Avşar
    • 1
  • Erşan Türkoğlu
    • 2
  • Martyn Unsworth
    • 3
  • İlyas Çağlar
    • 1
  • Bülent Kaypak
    • 4
  1. 1.Department of Geophysical Engineering, Faculty of MinesIstanbul Technical UniversityIstanbulTurkey
  2. 2.Quantec GeoscienceNorth YorkCanada
  3. 3.Department of PhysicsUniversity of AlbertaEdmontonCanada
  4. 4.Department of Geophysical Engineering, Faculty of EngineeringAnkara UniversityAnkaraTurkey

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