Geo-Marine Letters

, Volume 38, Issue 3, pp 211–225 | Cite as

Evidence of extensional and strike-slip deformation in the offshore Gökova-Kos area affected by the July 2017 Mw6.6 Bodrum-Kos earthquake, eastern Aegean Sea

  • Neslihan Ocakoğlu
  • Paraskevi Nomikou
  • Yeliz İşcan
  • Maria Filomena Loreto
  • Danai Lampridou


The interpretation of new multichannel seismic profiles and previously published high-resolution swath and seismic reflection data from the Gökova Gulf and southeast of Kos Island in the eastern Aegean Sea revealed new morphotectonic features related to the July 20, 2017 Mw6.6 Bodrum-Kos earthquake offshore between Kos Island and the Bodrum Peninsula. The seafloor morphology in the northern part of the gulf is characterized by south-dipping E–W-oriented listric normal faults. These faults bend to a ENE–WSW direction towards Kos Island, and then extend parallel to the southern coastline. A left-lateral SW–NE strike-slip fault zone is mapped with segments crossing the Gökova Gulf from its northern part to south of Kos Island. This fault zone intersects and displaces the deep basins in the gulf. The basins are thus interpreted as the youngest deformed features in the study area. The strike-slip faults also produce E–W-oriented ridges between the basin segments, and the ridge-related vertical faults are interpreted as reverse faults. This offshore study reveals that the normal and strike-slip faults are well correlated with the focal mechanism solutions of the recent earthquake and general seismicity of the Gökova Gulf. Although the complex morphotectonic features could suggest that the area is under a transtensional regime, kinematic elements normally associated with a transtensional system are missing. At present, the Gökova Gulf is experiencing strike-slip motion with dominant extensional deformation, rather than transtensional deformation.



This work combines two different projects. (1) The GEOWARN project (contract no. IST-1999-12310): the European Commission is acknowledged for their financial contribution, and the officers and crew of R/V Aegaeo are gratefully acknowledged for their substantial contribution to the field work. (2) Istanbul University Graduate Studies Research Funds (project no. 3347): the officers and crew as well as the scientists and technicians onboard the TCG Çubuklu and TCG Mesaha-II of the Turkish Navy, Department of Navigation, Hydrography and Oceanography are gratefully acknowledged for providing bathymetry data for the Gökova Gulf. The manuscript benefitted from constructive comments by two anonymous referees as well as the journal editors.

Compliance with ethical standards

Conflict of interest

The authors declare that there is no conflict of interest with third parties.


  1. AFAD (2017) Prime Ministry Disaster and Emergency Management Authority.
  2. Aktar M, Karabulut H, Childs D, Mutlu A, Ergin M, Yörük A, Geçgel V, Bulut F, Kaya T (2006) The active seismicity of Gökova Bay (in Turkish). Scientific and technical research Council of Turkey, Istanbul, TUBITAK project rep 104Y336Google Scholar
  3. Altınok Y, Ersoy Ş (2000) Tsunamis observed on and near the Turkish coast. Natural Hazards 21(2/3):185–205. CrossRefGoogle Scholar
  4. Bardintzeff JM, Dalabakis P, Traineau H, Brousse R (1989) Recent explosive volcanic episodes on the island of Kos (Greece): associated hydrothermal parageneses and geothermal area of Volcania. Terra Nova 1(1):75–78. CrossRefGoogle Scholar
  5. Barka A, Reilinger R (1997) Active tectonics of eastern Mediterranean region: deduced from GPS, neotectonic and seismicity data. Annali di Geofisica X2(3):587–610Google Scholar
  6. Böger H (1978) Sedimentary history and tectonic movements during the late Neogene. In: Closs H, Roeder D, Schmidt K (eds) Alps, Appenines, Hellenides. Schweizerbart, Stuttgart, pp 510–512Google Scholar
  7. Böger H, Gersonde R, Willman R (1974) Das Neogen im Osten der Insel Kos (Agäis, Dodekanes) – Stratigraphie und Tektonik. Neues Jahrbuch Geologie und Palaeontologie Abh 145:129–152Google Scholar
  8. Dalabakis P (1987) Une des plus puissante éruptions phréatomagmatiques dans la Méditerranée orientale: l’ignimbrite de Kos (Grèce). C R Acad Sci Paris 303(Série II):505–508Google Scholar
  9. Davis E, Gartzos E, Pavlopoulos A, Tsagalidis A (1993) Petrological and geochemical research of perlites and rhyolites from Kefalos peninsula (island of Kos) and their quantitative evaluation (in Greek). In: Special volume in honour of prof. A.G. Panagos, Athens A, pp 284–303Google Scholar
  10. Dewey JF, Şengör AMC (1979) Aegean and surrounding regions. Complex multiplate and continuum tectonics in a convergent zone. Geological Society of America Bulletin 90(1):84–92.<84:AASRCM>2.0.CO;2 CrossRefGoogle Scholar
  11. Emre Ö, Duman TY, Özalp S, Elmacı H, Olgun Ş, Şaroğlu F (2013) Active fault map of Turkey with and explanatory text. General Directorate of Mineral Research and Exploration, special publication series 30, Ankara, Turkey. ISBN: 978-605-5310-56-1Google Scholar
  12. Ergin K, Güçlü U, Uz Z (1967) The earthquake catalogue of Turkey and its surrounding area (in Turkish). İstanbul technical university, mining faculty press no 24Google Scholar
  13. Ganas A, Elias P, Valkaniotis S, Briole P, Kapetanidis V, Kassaras I, Barberopoulou A, Argyrakis P, Chouliaras G, Moshou A (2017) Co-seismic deformation and preliminary fault model of the July 20, 2017 M6.6 Kos earthquake. Aegean Sea Report. EMSC, 30 July 2017, Athens, Greece.
  14. Gibbs AD (1984) Structural evolution of extensional basin margins. Journal of the Geological Society of London 141(4):609–620. CrossRefGoogle Scholar
  15. Görür N, Şengör AMC, Sakınç M, Tüysüz O, Akkök R, Yiğitbaş E, Oktay FY, Barka A, Sarıca N, Ecevitoğlu B, Demirbağ E, Ersoy Ş, Algan O, Güneysu C, Akyol A (1995a) Rift formation in the Gökova region, southwest Anatolia: implications for the opening of the Aegean Sea. Geological Magazine 132(06):637–650. CrossRefGoogle Scholar
  16. Görür N, Şengör AMC, Sakınç M, Tüysüz O, Yiğitbaş E, Oktay FY, Barka A, Sarıca N, Ecevitoğlu B, Demirbağ E, Aykol A, Algan O, Güneysu C, Ersoy Ş (1995b) Cross-cutting rift systems of the Gökova region, SW Anatolia: implications for the formation of the Aegean Sea. Bull Tech Univ Istanbul 47(4):275–292Google Scholar
  17. İşcan Y (2010) Interpretation of geophysical data at Gökova Bay and surrounding area. MSc Thesis, Institute of Graduate Studies in Science and Engineering, IstanbulGoogle Scholar
  18. İşcan Y, Tur H, Gökaşan E (2013) Morphologic and seismic features of the Gökova gulf, SW Anatolia: evidence of strike-slip faulting with compression in the Aegean extensional regime. Geo-Marine Letters 33(1):31–48. CrossRefGoogle Scholar
  19. Jacobson D, Stein R, Sevilgen V (2017) Which fault ruptured in the M=6.6 Kos-Bodrum earthquake? 25 July 2017.
  20. Keller (1982) Mediterranean island arc. In: Thorpe RS (ed) Andesites. Wiley, New York, pp 307–325Google Scholar
  21. KOERI (2017) July 21 2017 Gökova gulf – Mediterranean earthquake report. B.U. Kandilli observatory and earthquake research institute, regional earthquake – tsunami monitoring center (RETMC), Istanbul, Turkey.ökova-korfezi-akdeniz-depremi/
  22. Kurt H, Demirbağ E, Kuşçu İ (1999) Investigation of the submarine active tectonism in the Gökova gulf, southwest Anatolia–southeast Aegean Sea, by multi-channel seismic reflection data. Tectonophysics 305(4):477–496. CrossRefGoogle Scholar
  23. Le Pichon X, Angelier J (1981) The Aegean Sea. Philosophical Transactions of the Royal Society of London. Series A 300(1454):357–372. CrossRefGoogle Scholar
  24. Mascle J, Martin L (1990) Shallow structure and recent evolution of the Aegean Sea: a synthesis based on continuous reflection profiles. Marine Geology 94(4):271–299. CrossRefGoogle Scholar
  25. McClusky S, Balassanian S, Barka A, Demir C, Ergintav S, Georgiev I, Gurkan O, Hamburger M, Hurst K, Kahle H, Kastens K, Kekelidze G, King R, Kotzev V, Lenk O, Mahmoud S, Mishin A, Nadariya M, Ouzounis A, Paradissis D, Peter Y, Prilepin M, Reilinger R, Sanli I, Seeger H, Tealeb A, Toksöz MN, Veis G (2000) Global positioning system constraints on plate kinematics and dynamics in the eastern Mediterranean and Caucasus. Journal of Geophysical Research 105(B3):5695–5719. CrossRefGoogle Scholar
  26. McKenzie DP (1972) Active tectonics of the Mediterranean region. Geophysical Journal of the Royal Astronomical Society 30(2):109–185. CrossRefGoogle Scholar
  27. NOA (2017) National Observatory of Athens, Geodynamic Institute, Greece, Athens.
  28. Nomikou P (2004) Geodynamics of Dodecanese islands: Kos and Nisyros volcanic field. PhD Thesis, Department of Geology, University of AthensGoogle Scholar
  29. Nomikou P, Papanikolaou D (2010a) A comparative morphological study of the Kos-Nisyros-Tilos volcano sedimentary basins. Bulletin of the Geological Society of Greece 43:464–474CrossRefGoogle Scholar
  30. Nomikou P, Papanikolaou D (2010b) The morphotectonic structure of Kos-Nisyros-Tilos volcanic area based on onshore and offshore data. In: proc XIX Congr Carpathian-Balkan geological association, 23–26 September 2010. Thessaloniki, Greece, spec vol 99:557–564Google Scholar
  31. Nomikou P, Papanikolaou D (2011) Extension of active fault zones on Nisyros volcano across the Yali-Nisyros Channel based on onshore and offshore data. Marine Geophysical Researches 32(1-2):181–192. CrossRefGoogle Scholar
  32. Nomikou P, Papanikolaou D, Alexandri M, Sakellariou D, Rousakis G (2013) Submarine volcanoes along the Aegean volcanic arc. Tectonophysics 507-508:123–146CrossRefGoogle Scholar
  33. Nomikou P, Hübscher C, Ruhnau M, Bejelou K (2016) Tectono-stratigraphic evolution through successive extensional events of the Anydros Basin, hosting of the Kolumbo volcanic field at Aegean Sea, Greece. Tectonophysics 671:202–217. CrossRefGoogle Scholar
  34. Nomikou P, Papanikolaou D, Dietrich VJ (2017a) Geodynamics and volcanism in the Kos-Yali-Nisyros volcanic field. In: Dietrich V, Lagios E (eds) Nisyros volcano: the Kos - Yali - Nisyros volcanic field. Springer, New York, pp 13–55Google Scholar
  35. Nomikou P, Ocakoğlu N, Işcan Y, Alp Y, Lampridou D, Papanikolaou D (2017b) Morpho-structural setting of the eastern part of the Aegean Sea (Kos-Nisyros-Tilos-Gökova region) revealed by high-resolution bathymetry. In: proc 16th Int Conf Geoinformatics: theoretical and applied aspects, SUB ID 43371, 15–17 may 2017, Kiev, UkraineGoogle Scholar
  36. Ocakoğlu N (2012) Investigation of Fethiye-Marmaris Bay (SW Anatolia): seismic and morphologic evidences from the missing link between the Pliny trench and the Fethiye-Burdur fault zone. Geo-Marine Letters 32(1):17–28. CrossRefGoogle Scholar
  37. Okay A, Demirbag E, Kurt H, Okay N, Kuscu I (1999) An active, deep marine strike-slip basin along the north Anatolian fault in Turkey. Tectonics 18(1):129–147. CrossRefGoogle Scholar
  38. Papanikolaou D (1993) Geotectonic evolution of the Aegean. Bulletin of the Geological Society of Greece 28(1):33–48Google Scholar
  39. Papanikolaou D, Lekkas E (1990) Miocene tectonism in Kos. Dodekanese islands. Int earth sciences Congr on Aegean. The Region:179–180Google Scholar
  40. Papanikolaou D, Nomikou P (1998) The Palaeozoic of Kos: a low grade metamorphic unit of the basement of the external Hellenides terrain. IGCP project no 276. Newsletter 6:155–166Google Scholar
  41. Reilinger R, McClusky S, Paradissis D, Ergintav S, Vernant P (2010) Geodetic constraints on the tectonic evolution of the Aegean region and strain accumulation along the Hellenic subduction zone. Tectonophysics 488(1-4):22–30. CrossRefGoogle Scholar
  42. Saltogianni V, Taymaz T, Yolsal-Çevikbilen S, Eken T, Gianniou M, Öcalan T, Pytharouli S, Stiros S (2017) Fault-model of the 2017 Kos-Bodrum (east Aegean Sea) mw 6.6 earthquake from inversion of seismological and GPS data – preliminary report. Department of Civil Engineering, University of Patras, Greece.
  43. Şaroğlu F, Emre Ö, Kuşçu İ (1992) Active fault map of Turkey (in Turkish). Scale 1:2.000.000. Mineral research exploration of Turkey press, AnkaraGoogle Scholar
  44. Şengör AMC (1979) Mid-Mesozoic closure of Permo–Triassic Tethys and its implications. Nature 279(5714):590–593. CrossRefGoogle Scholar
  45. Shah ST (2015) Stress tensor inversion from focal mechanism solutions and earthquake probability analysis of western Anatolia. MSc Thesis, School of Natural and Applied Sciences, Middle East Technical University, Ankara, TurkeyGoogle Scholar
  46. Sözbilir H, Uzel B, Sümer Ö, Eski S, Softa M, Tepe Ç (2017) 21 July 2017 Gökova Gulf earthquake and the seismicity of the region report (in Turkish). July 2017, Dokuz Eylul University earthquake research and application center (DAUM), İzmir, Turkey.
  47. Taymaz T, Price S (1992) The 1971 may 12 Burdur earthquake sequence, SW Turkey: a synthesis of seismological and geological observations. Geophysical Journal International 108(2):589–603. CrossRefGoogle Scholar
  48. ten Veen JH, Boulton SJ, Alçiçek MC (2009) From palaeotectonics to neotectonics in the Neotethys realm: the importance of kinematic decoupling and inherited structural grain in SW Anatolia (Turkey). Tectonophysics 473(1-2):261–281. CrossRefGoogle Scholar
  49. Tibaldi A, Pasquaré FA, Papanikolaou D, Nomikou P (2008) Tectonics of Nisyros Island, Greece, by field and offshore data, and analogue modelling. Journal of Structural Geology 30(12):1489–1506. CrossRefGoogle Scholar
  50. Tiryakioğlu İ, Aktuğ B, Yiğit CÖ, Yavaşoğlu HH, Sözbilir H, Özkaymak Ç, Poyraz F, Taneli E, Bulut F, Doğru A, Özener H (2017) Slip distribution and source parameters of the 20 July 2017 Bodrum-Kos earthquake (Mw6.6) from GPS observations. Geodinamica Acta 30(1):1–14CrossRefGoogle Scholar
  51. Triantaphyllis M (1994) Geological map of Greece, western Kos, sheet (Kefalos) 1:50,000. Inst, Geology Mineral Exploration (IGME), AthensGoogle Scholar
  52. Tur H, Yaltırak C, Elitez İ, Sarıkavak KT (2015) Pliocene–quaternary tectonic evolution of the Gökova gulf, southwest Turkey. Tectonophysics 638:158–176. CrossRefGoogle Scholar
  53. Uluğ A, Duman M, Ersoy Ş, Özel E, Avcı M (2005) Late Quaternary sea-level change, sedimentation and neotectonics of the Gökova gulf: southeastern Aegean Sea. Marine Geology 221(1-4):381–395. CrossRefGoogle Scholar
  54. USGS (2017) United States Geological Survey National Earthquake Information Center, USA.
  55. Vernant P, Reilinger R, McClusky S (2014) Geodetic evidence for low coupling on the Hellenic subduction plate interface. Earth and Planetary Science Letters 385:122–129. CrossRefGoogle Scholar
  56. Yalçıner AC, Annunziato A, Papadopoulos G, Dogan GG, Guler HG, Cakır TE, Sozdinler CO, Ulutaş E, Arikawa T, Süzen L, Kanoğlu U, Güler I, Probst P, Synolakis C (2017) The 20th July 2017 (22:31 UTC) Bodrum/Kos earthquake and tsunami; post tsunami field survey report, July 27 2017, Istanbul, Turkey.
  57. Yılmaz Y, Genç ŞC, Gürer F, Bozcu M, Yılmaz K, Karacık Z, Altunkaynak Ş, Elmas A (2000) When did the western Anatolian grabens begin to develop? In: Bozkurt E, Winchester JA, piper JDA (eds) tectonics and magmatism in Turkey and surrounding area. Geological Society of London, Special Publication 173(1):353–384. CrossRefGoogle Scholar
  58. Yolsal S, Taymaz T, Yalçiner AC (2007) Understanding tsunamis, potential source regions and tsunami-prone mechanisms in the eastern Mediterranean. Geological Society of London, Special Publication 291(1):201–230. CrossRefGoogle Scholar
  59. Yolsal-Çevikbilen S, Taymaz T (2012) Earthquake source parameters along the Hellenic subduction zone and numerical simulations of historical tsunamis in the eastern Mediterranean. Tectonophysics 536-537:61–100. CrossRefGoogle Scholar
  60. Yolsal-Çevikbilen S, Taymaz T, Helvacı C (2014) Earthquake mechanisms in the gulfs of Gökova, Sığacık, Kuşadası, and the Simav region (western Turkey): neotectonics, seismotectonics and geodynamic implications. Tectonophysics 635:100–124. CrossRefGoogle Scholar

Copyright information

© Springer-Verlag GmbH Germany, part of Springer Nature 2017

Authors and Affiliations

  1. 1.Department of Geophysical Engineering, Faculty of MinesIstanbul Technical UniversityIstanbulTurkey
  2. 2.Department of Geology and GeoenvironmentNational and Kapodistrian University of AthensAthensGreece
  3. 3.Department of Geophysics, Faculty of EngineeringIstanbul UniversityIstanbulTurkey
  4. 4.Institute of Marine Sciences, CNRBolognaItaly

Personalised recommendations