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

Ocakoğlu, Neslihan; Nomikou, Paraskevi; İşcan, Yeliz; Loreto, Maria Filomena; Lampridou, Danai

doi:10.1007/s00367-017-0532-4

Cited by 22 publications

(19 citation statements)

References 32 publications

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“…The reflection profiles along the eastern Gulf show multiple horst and graben structures aligned more or less east-west (Figure 2). In the western Gulf, where the 2017 earthquake struck, there are several south-dipping faults on the north side (Ocakoğlu et al, 2018), and the north-dipping Datça Fault in the southern Gulf. Given the absence of an observed surface break, and the complexity and limited available information on faulting in the Gulf, the structural evidence for constraining the location and source of the 2017 coseismic fault is at best equivocal.…”

Section: Tectonic Settingmentioning

confidence: 99%

“…On the other hand, in the western part of the gulf, where the 2017 earthquake struck, there are several south-dipping faults with surface expressions toward the north of the Gulf and one major north-dipping fault with significant vertical offset, named the Datça fault by the authors (Figure 2). A more recent study of the Gulf of Gökova based on multichannel seismic reflection (Ocakoğlu et al, 2018) argued that the south-dipping faults with surface expressions on the northern edge of the Gulf are dominant, while the faults with surface expressions in the south are mostly oblique, left-lateral faults. On this basis, the authors suggest that the 2017 earthquake possibly broke a south-dipping fault.…”

Section: Introductionmentioning

confidence: 99%

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Slip distribution of the 2017 Mw6.6 Bodrum–Kos earthquake: resolving the ambiguity of fault geometry

Konca

Güvercin

Özarpacı

et al. 2019

Geophysical Journal International

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SUMMARY The 2017 July 20, Mw6.6 Bodrum–Kos earthquake occurred in the Gulf of Gökova in the SE Aegean, a region characterized by N–S extension in the backarc of the easternmost Hellenic Trench. The dip direction of the fault that ruptured during the earthquake has been a matter of controversy where both north- and south-dipping fault planes were used to model the coseismic slip in previous studies. Here, we use seismic (seismicity, main shock modelling, aftershock relocations and aftershock mechanisms using regional body and surface waves), geodetic (GPS, InSAR) and structural observations to estimate the location, and the dip direction of the fault that ruptured during the 2017 earthquake, and the relationship of this event to regional tectonics. We consider both dip directions and systematically search for the best-fitting locations for the north- and south-dipping fault planes. Comparing the best-fitting planes for both dip directions in terms of their misfit to the geodetic data, proximity to the hypocenter location and Coulomb stress changes at the aftershock locations, we conclude that the 2017 earthquake ruptured a north-dipping fault. We find that the earthquake occurred on a 20–25 km long, ∼E–W striking, 40° north-dipping, pure normal fault with slip primarily confined between 3 and 15 km depth, and the largest slip exceeding 2 m between depths of 4 and 10 km. The coseismic fault, not mapped previously, projects to the surface within the western Gulf, and partly serves both to widen the Gulf and separate Kos Island from the Bodrum Peninsula of SW Anatolia. The coseismic fault may be an extension of a mapped, north-dipping normal fault along the south side of the Gulf of Gökova. While all of the larger aftershocks are consistent with N–S extension, their spatially dispersed pattern attests to the high degree of crustal fracturing within the basin, due to rapid trenchward extension and anticlockwise rotation within the southeastern Aegean.

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Section: Tectonic Settingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Slip distribution of the 2017 Mw6.6 Bodrum–Kos earthquake: resolving the ambiguity of fault geometry

Konca

Güvercin

Özarpacı

et al. 2019

Geophysical Journal International

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“…Plate movements involving the convergence of Arabia and Africa with Eurasia in the north; 1) give rise to the westward extrusion of Anatolia along the strike-slip North Anatolian Fault (NAF) and East Anatolian Fault (EAF), 2) cause crustal extension in western Anatolia-Aegean, and 3) are responsible for complex deformation in the Eastern Mediterranean region (McKenzie, 1972;Dewey and Şengör, 1979;Le Pichon and Angelier, 1979;Angelier et al, 1981;McKenzie, 1984, 1988;Taymaz et al, 1990;Över et al, 2010;Özden et al, 2018). The complex tectonics of western Anatolia-Aegean involve different extensional regimes: N-S, NE-SW, and NW-SE (McKenzie, 1972;Jolivet and Brun, 2010;Alçiçek et al, 2006;Shah, 2015;Över et al, 2016;Ocakoğlu et al, 2018).…”

Section: Recordmentioning

confidence: 99%

“…From analysis of the focal mechanisms, Shah (2015) asserted that the area is dominated by normal events with few strike-slip events at the western margin of Gökova Gulf. The interpretation of new multichannel seismic profiles by Ocakoğlu et al (2018) . Normal faults were also implied in the Gökova Basin by several studies (e.g., Kurt et al, 1999;Uluğ et al, 2005;İşcan et al, 2013;Tur et al, 2015;Ocakoğlu et al, 2018).…”

Section: Recordmentioning

confidence: 99%

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20 July 2017 Bodrum-Kos Earthquake (Mw:6.6) in southwestern Anatolia, Turkey

et al. 2021

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In the Aegean Sea, the western part of Gökova Gulf, Kos and Bodrum were struck by a 6.6 (Mw) earthquake on July 20, 2017. The fault plane solution for the main shock shows an E-W striking normal type fault with approximately N-S (N4°E) tensional axis (T-axis). Fault plane solutions of 33 aftershocks show two groups of normal type fault with E-W and NE-SW to ENE-WSW orientations. The inversion of the focal mechanisms of the aftershocks yields two different normal faulting stress regimes: one is characterized by an approximately N-S (N5°E) σ3 axis (minimum horizontal stress axis). This extension is obtained from 13 focal mechanisms of aftershocks with approximately E-W direction. The other is characterized by approximately NW-SE (N330°E) σ3 axis. The latter is calculated from 21 seismic faults of aftershocks with approximately NE-SW direction. These aftershocks occurred on relatively small-scale faults that were directed from NE-SW to ENE-WSW, and possibly contributed to expansion of the basin in the west. The 24 focal mechanisms of earthquakes which occurred since 1933 in and around Gökova Basin are introduced into the inversion analysis to obtain the stress state effective in a wider region. The inversion yields an extensional stress regime characterized by an approximately N-S (N355°E) σ3 axis. The E-W directional metric faults, measured in the central part of Gökova Fault Zone bordering the Gökova Gulf in the north, also indicate N-S extension. The NE-SW extension obtained from NE-SW aftershocks appears to be more local and is responsible for the expansion of the western part of the asymmetric Gökova Basin. This N-S extension which appears to act on a regional-scale may be attributed to the geodynamic effects related to the combined forces of the southwestward extrusion of Anatolia and the roll-back process of African subduction beneath Anatolia.

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