The 2005 - 2007 Bala (Ankara, central Turkey) earthquakes: a case study for strike-slip fault terminations
DOI:
https://doi.org/10.1344/105.000002075Keywords:
Strike-slip faults, Fault terminations, Tuzgölü fault zone, Neotectonics, Bala earthquake, AnatoliaAbstract
An intense seismic activity has been observed after the Bala (Ankara, NW central Turkey) earthquakes (30 July 2005: Mw=5.3, 20 December 2007: Mw=5.4, and 26 December 2007: Mw=5.3), continuing up to the present. The epicenters and the focal mechanism solutions of the earthquakes indicate that the right lateral strike-slip Afşar fault, trending N55-60°W, is responsible for the main shocks. The Afşar fault is thought to be the NW continuation of the Tuzgölü fault zone, which is one of the main neotectonic elements in central Anatolia. On the other hand, the aftershock distributions of the 2005 event have a NNE trend, and those of the 2007 event show a NW trending. Some focal mechanism solutions of the 2005 Bala earthquake aftershocks indicate normal and oblique normal faulting that corresponds to the NNE-trending Karakeçili fault. It seems that seismic activation of the NNE-trending Karakeçili fault was triggered by the 2005 main shock (Mw=5.3) that occurred on the NW trending right lateral strike-slip Afşar fault. The overall neotectonic framework is that the northwestern edge of the Tuzgölü fault zone, represented by the Afşar fault in Bala, terminates in an extensional system represented by the oblique-slip Karakeçili fault.
References
Akçay, A.E., Dönmez, M., Kara, H., Yergök, A.F., Esentürk, K., 2008. Geological map of the Kırşehir-J30 quadrangle (1/100000 scaled). General Directorate of Mineral Research and Exploration, Ankara (Turkey).
Ambraseys, N.N., Finkel, C.F., 1995. Seismicity of Turkey and adjacent areas, a historical review, 1500-1800. İstanbul, Eren Yayıncılık ve Kitapçılık Ltd, 224pp.
Barka, A., Reilinger, R., 1997. Active tectonics of the Eastern Mediterranean region: deduced from GPS, neotectonic and seismicity data. Annali Di Geofisica, 40(3), 587-610.
Başokur, A.T., Gökten, E., Seyitoğlu, G., Varol, B., Ulugergerli, E., Işık, V., Candansayar, E., Tokgöz, E., 2002. The mechanisms of the 03.02.2002 Çay (Afyon) earthquake, causes of the damage, and the seismic activity of the region in the light of the geological and geophysical studies (in Turkish). Ankara, Ankara University, Faculty of Engineering, 56pp.
Çıvgın, B., Kaypak, B., 2012. Investigation of one-dimensional crustal seismic velocity structure of Ankara and surroundings (in Turkish with English abstract). Yerbilimleri, 33(2), 131-150.
Çubuk, Y., Taymaz, T., 2009. Time domain moment tensor analysis of 2005−2008 Bala (Ankara) earthquakes. Ankara, 62nd Geological Congress of Turkey, Abstract, 780-781.
Dewey, J.F., Hempton, M.R., Kidd, W.S.F., Saroglu, F., Şengör, A.M.C., 1986. Shortening of continental lithosphere: the neotectonics of Eastern Anatolia - a young collision zone. In: Coward, M.P., Ries, A.C. (eds.). Collision Tectonics. London, Geological Society, Special Publication, 3-36.
Dirik, K., Özsayın, E., Kutluay, A., 2008. Source of the seismic activity in the south of Ankara (central Anatolia) during last three years. Ankara, 61st Geological Congress of Turkey, Abstract, 76-77.
Emre, Ö., Duman, T.Y., Doğan, A., Özalp, S., Tokay, F., Kuşçu, İ., 2003. Surface faulting associated with the Sultandağı earthquake (Mw 6.5) of 3 February 2002, southwestern Turkey. Seismological Research Letters, 74(4), 382-392.
Erol, O., 1954. Geology of Ankara and its surroundings (in Turkish). General Directorate of Mineral Research and Exploration of Turkey Report, 2491, unpublished, 306pp.
Esat, K., Çıvgın, B., Kaypak, B., Işık, V., Seyitoğlu, G., 2009. The nature of the Bala (Ankara) faults causing earthquakes and their meaning within the general neotectonic framework in the light of the geological and seismological data. Ankara, 62nd Geological Kurultai of Turkey, Abstract, 810-811.
Kalafat, D., Kekovali, K., Pinar, A., 2008. The 30 July 2005 (Mw=5.4) and the 20-26 December 2007 (Mw=5.5; Mw=5.3) Afsar-Bala (Ankara) earthquake series in central Turkey. Geophysical Research Abstracts, 10, EGU2008-A-09923.
Kasapoğlu, K.E., Öztürk, E., Tetik, Ç., Bay, A., 2005. Site investigation report of the 31 July 2005 Bala (Ankara) earthquake (in Turkish). Ankara, Hacettepe University, Department of Geological Engineering, 23pp.
Kikuchi, M., Kanamori, H., 1991. Inversion of complex body waves III. Bulletin of the Seismological Society of America, 81, 2335-2350.
Kingma, J.T.,1958. Possible of Piercement structures, local unconformities, and secondary basins in the Eastern Geosyncline, New Zealand. New Zealand Journal of Geology and Geophysics, 1, 269-274
Kocaefe, S.S., Ataman, G., 1982. Actual tectonics of the western Anatolia (in Turkish with English abstract). Yerbilimleri, 9,
-162.
Koçyiğit, A., 1991. An example of an accretionary forearc basin from northern Central Anatolia and its implications for the history of subduction of Neo-Tethys in Turkey. Geological Society of America Bulletin, 103, 22-36.
Koçyiğit, A., 2003. General tectonic characteristics and seismicity of Ankara region (in Turkish with English abstract). Turkish
Association of Petroleum Geologists Bulletin, 5 (Special Publications), 1-26.
Koçyiğit, A., 2009. Seismicity of Ankara and source of the 2005-2007 Afşar (Bala-Ankara) earthquakes (in Turkish with English abstract). Harita Dergisi, 141, 1-12.
Koçyiğit, A., Özacar, A.A., 2003. Extensional neotectonic regime through the NE edge of the outer Isparta Angle, SW Turkey:
new field and seismic data. Turkish Journal of Earth Sciences, 12, 67-90.
Koçyiğit, A., Türkmenoğlu, A., Beyhan, A., Kaymakçı, N., Akyol, E., 1995. Post-collisional tectonics of EskisehirAnkara-Çankiri segment of Izmir-Ankara-Erzincan suture zone (IAESZ): Ankara orogenic phase. Turkish Association of Petroleum Geologists Bulletin, 6(1), 69-86.
Marrett, R., Allmendinger, R.W., 1990. Kinematic analysis of fault-slip data. Journal of Structural Geology, 12(8), 973-986.
McKenzie, D., 1972. Active tectonics of the Mediterranean region. Geophysical Journal of the Royal Astronomical Society, 30, 109-185.
Özsayın, E., Dirik, K., 2007. Quaternary activity of the Cihanbeyli and Yeniceoba Fault Zones: İnönü-Eskişehir Fault System, central Anatolia. Turkish Journal of Earth Sciences, 16, 471-492.
Rojay, B., Karaca, A., 2008. Post-Miocene deformation in the south of the Galatean Volcanic Province, NW of central Anatolia (Turkey). Turkish Journal of Earth Sciences, 17, 653-672.
Downloads
Published
Issue
Section
License
This work is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.
Copyright
Geologica Acta is the property of the UB, GEO3BCN, IDAEA and UAB. Geologica Acta must be cited for any partial or full reproduction. Papers are distributed under the Attribution-Share Alike Creative Commons License. This license allows anyone to reproduce and disseminate the content of the journal and even make derivative works crediting authorship and provenance and distributing possible derivative works under the same or an equivalent license.
Author Rights
Authors retain the copyright on their papers and are authorized to post them on their own web pages or institutional repositories. The copyright was retained by the journal from the year 2003 until 2009. In all cases, the complete citation and a link to the Digital Object Identifier (DOI) of the article must be included.
The authors can use excerpts or reproduce illustrations of their papers in other works without prior permission from Geologica Acta provided the source of the paper including the complete citation is fully acknowledged.
