Ali KOÇYİĞİT, Mustafa CİHAN, Bora ROJAY, Arda ÖZACAR

1712

The June 6, 2000, Orta (Çankırı, Turkey) earthquake: Sourced from a new antithetic sinistral strike-slip structure of the North Anatolian fault system, the Dodurga fault zone

Kuzey Anadolu Fay Sisteminin (KAFS) İsmetpaşa-Kargı bölümü Eskipazar, Ulusu, Tosya, Çerkeş-Kurşunlu, Devrez ve yeni tanımlanan Dodurga fay kuşağı (DKF) olmak üzere altı adet alt-fay kuşaklarından oluşur. Bu fay kuşaklarının tamamı iyi gelişmiş sağ yanal-atımlı fay deseni oluşturur ve bu sistem içerisinde DFK yanal atım bileşeni! ikincil antitetik yapıyı temsil eder. Yaklaşık 36 km uzunluğunda ve kuzey-güney uzanımlı bir yanal-atımlı fay olan DFK, kuzey de Saçak ve güneyde Kösrelik köyleri arasında yeralır. Üst Pliyosen öncesi kaya topluklarını kesen ve öteleyen fay kuşağı boyunca belirlenen hareket 6 km kadardır. Devrez ırmağının memba dereleri "S" şekilli dönmüş ve sol yanal olarak 2.5 km' ye kadar atılmıştır. Bu değerler, DFZ üzerinde 2.3 mm/yr kayma miktarı verir. Bunlara ilaveten DFZ üzerinde birçok Pliyo-Kuvaterner çek-ayır havzalar gelişmiştir. Orta ölçekli (Mw = 6.0) ve sığ odaklı, Orta depremi, 6 Haziran 2000 salı sabahı saat 5.42 (yerel zaman ile) Orta bölgesini vurdu. Deprem, iki ölüme ve çoğu ağır olmak üzere kırsal tarzda inşa edilmiş toplam 4842 yapının hasar görmesine neden oldu. Çoğunlukla hasar DFZ'nin ana kolu olan Dodurga fayı üzerinde dar bir kuşakta oluştu. Eşdeğersismik eğrilerinin uzun ekseni Dodurga fayına parallel uzanan elipsoidal bir desen oluşturur. 6 Haziran 2000 Orta Depremin öncül ve ardçıl depremlerinin dağılımı kuzey-güney yönünde bir yoğunlaşma gösterip, Dodurga fay kuşağına paralellik sunarlar. DER-DDR dışında çeşitli sismograf istasyonlarında yapılan odak mekanizması çözümlemeleri normal bileşenli sol yanal-atımlı faylanma göstermektedir. Sonuç olarak, arazi jeolojisi gözlemleri ve sismik veriler birlikte Dodurga fayının KAFS'i içinde antitetik sol yanal-atımlı fay olduğunu ve 6 Haziran 2000 Orta depreminin bu fayın hareketlenmesi ile oluştuğunu ortaya koymaktadır.

Kuzey Anadolu fay sisteminde tanımlanan sol yanal atımlı bir fay kuşağı Dodurga fay kuşağı ve 6 Haziran 2000 tarihli Orta (Çankırı-Türkiye) depremi

The Ismetpaşa-Kargı section of the North Anatolian Fault System (NAFS) consists of six subfault zones, namely the Eskipazar, the Ulusu, the Tosya, the Çerkeş-Kurşunlu, the Devrez and the newly detected Dodurga fault zone (DFZ). Together these fault zones form a well-developed dextral strike-slip-faulting pattern, in which the DFZ is an antithetic secondary strike-slip component, indicated by focal-mechanism solutions of moderate and large earthquakes that have occurred in the Ismetpaşa-Kargı section of the NAFS. The DFZ is a $sim$36-km-long, $sim$N-S-trending strike-slip structure located in the area between Saçak village in the north and Kösrelik village in the south. Pre-Upper Pliocene rocks are cut and tectonically offset for a distance of about 6 km. Upstream tributaries of the Devrez River are deviated in the shape of an "S" and are offset sinistrally up to 2.5 km. These values explain a 2.3 mm/yr rate of slip on the DFZ. In addition, several Plio-Quaternary pull-apart basins occur within the DFZ. An intermediate-magnitude (Mw= 6.0), shallow-focus earthquake, the Orta earthquake, struck on Tuesday, June 6, 2000, at 5:42 (local time) in the Orta area, and resulted in two deaths and severe damage to a total of 4842 structures, almost all of rural-style construction. Most of severe damage was confined to a narrow area along the Dodurga fault; that is, the master strand of the DFZ. Isoseismal lines display an ellipsoidal pattern with a long axis that parallels the Dodurga fault. Both fore- and after-shocks of the June 6, 2000 Orta earthquake form a highly concentrated, N-S-trending distribution pattern that parallels the DFZ. Focal-mechanism solutions of the main shock carried out by various seismographic stations, except for DER-DDR station, indicate sinistral strike-slip faulting with a normal-slip component. Consequently, taken together these field observations and seismological data indicate that the Dodurga fault is an antithetic sinistral strike-slip structure included in the NAFS, and that the June 6, 2000 Orta earthquake resulted from its activation.
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  • ALSAN, E., TEZUÇAN, L. & BATH, M. 1975. An Earthquake Catalogue for Turkey for the Interval 1913-1970. Kandilli Observatory, Seismological Department, İstanbul, Turkey, 160 p.
  • AMBRASEYS, N.N. 1970. Some characteristic features of the North Anatolian fault zone. Tectonophysics9, 143-165.
  • AMBRASEYS, N.N. & FINKEL, C.F. 1987. Seismicity of Turkey and neighbouring regions, 1899-1915. Annales Geophysicae 87, 701-725.
  • AMBRASEYS, N.N. & JACKSON, J.A. 1998. Faulting associated with historical and recent earthquakes in the eastern Mediterranean region. Geophysical Journal International 133, 390-406.
  • ANDRIEUX, J., ÖVER, S., POISSON, A., BELLIER, 0. 1995. The North Anatolian fault zone: distributed Neogene deformation in its northward convex part. Tectonophysics 243, 135-154.
  • BARKA, A. & HANCOCK, P.L. 1984. Neotectonic deformation patterns in the convex-northwards arc of the North Anatolian Fault. In: DIXON, J.G. & ROBERTSON, A.H.F. (eds), The Geological Evolution of the Eastern Mediterranean. Geological Society, London, Special Publications 17, 763-773.
  • BARKA, A. & GÜLEN, L. 1988. New constraints on age and total offset of the North Anatolian fault zone: implications for tectonics of the Eastern Mediterranean region. METU Journal of Pure and Applied Sciences 21, 39-63.
  • BARKA, A. & KADINSKY-CADE, C. 1988. Strike-slip fault geometry in Turkey and its influence on earthquake activity. Tectonics 7, 663-684.
  • BLUMENTAL, M., 1945. Ladik Deprem Hattı (Samsun İli) [Ladik Earthquake Zone, Samsun]. Mineral Research and Exploration Institute of Turkey Publications 1/33, 153-162 [in Turkish].
  • BOZKURT, E. & KOÇYİĞİT, A. 1995. Almus fault zone: its age, total offset and relation to the North Anatolian fault zone. Turkish Journal of Earth Sciences 4, 93-104.
  • BOZKURT, E. & KOÇYIĞİT, A. 1996. The Kazova basin: an active negative flower structure on the Almus fault zone, a splay fault system of the North Anatolian fault zone, Turkey. Tectonophysics 256, 239-254.
  • CANITEZ, N. 1973. Yeni kabuk hareketlerine ilişkin çalışmalar ve Kuzey Anadolu fay problemi [New works on recent crustal movements and the problem of North Anatolian Fault]. Kuzey Anadolu Fayı ve Deprem Kuşağı Simpozyumu, 29-31 Mart, Ankara, Tebliğler, 35-58 [in Turkish].
  • CANITEZ, N. & ÜÇER, B. 1967. A Catalogue of Focal Mechanism Diagrams for Turkey and Adjoining Areas. İstanbul Teknik Üniversitesi, Maden Fakültesi, Arz Fiziği Enstitüsü Yayınları 25, 111 p.
  • CANITEZ, N. & BÜYÜKAŞIKOĞLU, S. 1984. Seismicity of the Sinop Nuclear Power Plant Site. Final Report, Istanbul Teknik Üniversitesi, İstanbul.
  • DEMİRTAŞ, R., ERKMEN, C. & YAMAN, M. 2000. 06 Haziran 2000 Orta (Çankırı) Depremi (MI= 5.9) [06 June 2000 Orta (Çankırı) Earthquake (Ml= 5.9]. Aktif Tektonik Araştırma Grubu Dördüncü Toplantısı, 16-17 Kasım 2000, Eskişehir, Abstracts, 9-10 [in Turkish].
  • DEMETS, C, GORDON, R., ARGUS, D. & STEIN, S. 1994. Effect of recent revisions to the geomagnetic reversal time scale on estimates of current plate motions. Geophysical Research Letters 21, 2191-2194.
  • EMRE, Ö., DUMAN, T.Y., DOĞAN, A. & ÖZALP, S. 2000. 06 Haziran 2000 Orta (Çankırı) Depremi Değerlendirme Raporu [A report on the 06 June 2000 Orta-Çankırı Earthquake]. Mineral Reseach and Exploration Institute of Turkey, Geology Department, 19 p [in Turkish].
  • ERGİN, K., GÜÇLÜ, U. & Uz, Z., 1967. Türkiye ve Civarının Deprem Katoloğu (Milattan sonra 11 Yılından 1964 Sonuna Kadar). [An Earthquake Catalogve for Turkey and its Surroundings for the interial 11-1964] İstanbul Teknik Üniversitesi, Maden Fakültesi, Arz Fiziği Enstitüsü Yayınları 24, 169 p [in Turkish].
  • GÜRSOY, H., TATAR, 0. & TEMİZ, H. 1997. A paleomagnetic study of the Sivas Basin, central Turkey: crustal deformation during lateral extrusion of the Anatolian Block. Tectonophysics 271, 89-105.
  • HEMPTON, M.R. 1987. Constraints on Arabian plate motion and extensional history of the Red Sea. Tectonics 6, 687-705.
  • JACKSON, J. & MCKENZIE, D. 1984. Active tectonics of the Alpine-Himalayan belt between western Turkey and Pakistan. Geophysical Journal Royal Astronomical Society 77, 185-264.
  • KAHLE, H.G., STRAUB, C, REILINGER, R., MCCLUSKY, S., KING, R., HURST, K., VEIS, G., HASTENS, K. & CROSS, P. 1998. The strain rate field in the eastern Mediterranean region, estimated by repeated GPS measurements. Tectonophysics 294, 237-252.
  • KAHLE, H.G., COCARD, M., PETER, Y., GEIGER, A., REIUNGER, R., BARKA, A., VEIS, G. 2000. GPS-derived strain rate field within the boundary zones of the Eurasian, African and Arabian plates. Journal of Geophysical Research 105, 23353-23370.
  • KASAPOĞLU, E. & TOKSÖZ, M.N. 1983. Tectonic consequences of the collision of the Arabian and Eurasian plates: finite element models. Tectonophysics 100, 71 -96.
  • KAYMAKÇI, N. & KOÇYİĞİT, A. 1995. Mechanism and basin generation in the splay fault zone of the North Anatolian fault zone. EUG. 8th Conference on the Earth Sciences, Strasbourg.
  • KAYMAKÇI, N., 2000. Tectono-stratigraphical evolution of the Çankırı Basin (central Anatolia, Turkey). Universiteit Utrecht, PhD Thesis, 1TC Publication No. 71, ISBN 90-6164-181-0, 247 p.
  • KAYMAKÇI, N. 2000. Palaeostress inversion in a multiphase deformed area: kinematic and structural evolution of the Çankırı Basin (central Turkey), Part 1-northern area. In: BOZKURT, E., WINCHESTER, J.A. & PIPER, J.D.A. (eds), Tectonics and Magmatism in Turkey and the Surrounding Area. Geological Society London, Special Publications 173, 295-323.
  • KETIN, İ., 1969. Uber die Nordanatolische Horizontalverschiebung. Mineral Research and Exploration Institute of Turkey Bulletin 72, 1-28.
  • KOÇYİĞİT, A. 1988. Tectonic setting of the Geyve basin: age and total offset of the Geyve fault zone, E. Marmara, Turkey. METU Journal of Pure and Applied Sciences 21, 81 -104.
  • KOÇYİĞİT, A. 1989. Suşehri basin: an active fault-wedge basin on the North Anatolian fault zone, Turkey. Tectonophysics 167, 13-29.
  • KOÇYİĞİT, A. 1990. Tectonic setting of the Gölova basin: total offset of the North Anatolian fault zone, E. Pontides, Turkey. Annales TectonicaeWt, 155-170.
  • KOÇYİĞİT, A. 1991a. Changing stress orientation in progressive intracontinental deformation as indicated by the neotectonics of the Ankara region (NW Central Anatolia). Turkish Association of Petroleum Geologists Bulletin 3, 43-55.
  • KOÇYİĞİT, A. 1991b. Neotectonic structures and related landforms expressing the contractional and extensional strains along the North Anatolian fault at the northwestern margin of the Erzincan basin, NE Turkey. Bulletin of İstanbul Technical University 44, 455-473.
  • KOÇYİĞİT, A. 1996. Superimposed basins and their relations to recent strike-slip fault zone: a case study of the Refahiye superimposed basin adjacent to the North Anatolian transform fault, northwestern Turkey. International Geology Review 38, 701-713.
  • KOÇYİĞİT, A., TÜRKMENOĞLU A., BEYHAN, A., KAYMAKÇI, N. & AKYOL, E. 1995. Post-collisional Tectonics of Eskişehir-Ankara-Çankırı segment of İzmir-Ankara-Erzincan suture zone (1AESZ): Ankara orogenic phase. Turkish Association of Petroleum Geologists Bulletin 6, 69^86.
  • KOÇYİĞİT, A., & BEYHAN, A. 1998. A new intracontinental transcurrent structure: the Central Anatolian fault zone, Turkey. Tectonophysics 284, 317-336.
  • KOÇYİĞİT, A. & BEYHAN, A. 1999. Replay to Rob Westaway's comment on "A new intracontinental transcurrent structure: the Central Anatolian fault zone" Turkey. Tectonophysics 314, 481-496.
  • KOÇYİĞİT, A., BOZKURT, E., CİHAN, M., ÖZACAR, A. & TEKSÖZ, B. 1999. Neotectonic frame of Turkey: a special emphasis on the 17 August 1999 Gölcük-Arifiye earthquake (NE Marmara, Turkey). International Conference on Earthquake Hazard and Risk in the Mediterranean Region, 18-22 October 1999, Near East University, Proceedings, 1-11.
  • LE PICHON, X. & ANGELIER, J. 1979. The Hellenic arc and trench system: A key to the neotectonic evolution of the eastern Mediterranean area. Tectonophysics 60, 1-42.
  • MCCLUSKY, S., BALASSANIAN, S., BARKA, A., DEMİR, C, ERGİNTAV, S., GEORGIEV, 1., GÜRKAN, 0., HAMBURGER, M., HURST, K., KAHLE, H., KASTENS, K., KEKELIDZE, G., KING, R., KADZEV, V., LENK, 0., MAHMOUD, S., MISHIN, A., NADARIYA, M., OUZOUNIS, A., PARADISSIS, D., PETER, Y., PRILEPIN, M., REILINGER, R., ŞANLI, I., SEEGER, H., TEALEB, A., TOKSÖZ, M.N. & VEIS, G. 2000. Global positioning system constraints on plate kinematics and dynamics in the eastern Mediterranean and Caucasus. Journal of Geophysical Research 105,5695-5719.
  • MCKENZIE, D.P. 1969. The relation between fault plane solutions for earthquakes and the directions of the principal stresses. Bulletin of the Seismological Society of America 59, 591 -601.
  • MCKENZIE, D.P., 1972. Active tectonics of the Mediterranean region. Geophysical Journal of Royal Astronomical Society 30, 109-185.
  • MEULENKAMP, J. E., WORTEL, M. J. R., VAN WAMEL, W. A., SPAKMAN, W. & Hoogerduyn Strating, E. 1998. On the Hellenic subduction zone and the geodynamic evolution of Crete since the late Middle Miocene. Tectonophysics 146, 203-215.
  • NORTH, R. 1974. Seismic slip rates in the Mediterranean and Middle East. Nature 252, 560-563.
  • NOWROOZI, A.A. 1972. Focal mechanism of earthquakes in Persia, Turkey, west Pakistan, and Afghanistan and plate tectonics of the Middle East. Seismological Society of America Bulletin 62, 823-850.
  • ÖZAKSOY, V. 2000. Çerkeş-llgaz segmentinde Kuzey Anadolu fay zonu'nun sismotektoniği [Seismotectonics of the North Anatolian Fault Zone in the Area Between Çerkeş and Ilgaz]. Ankara University, PhD Thesis, 116 p [unpublished in Turkish].
  • ÖZAKSOY, V., GÖKTEN, E. & DEMİRTAŞ, R. 1998. .Kuzey Anadolu fayı Gerede segmenti doğu kesiminde aktif tektonik çalışmaları: İsmetpaşa trençi ön sonuçları [Active neotectonic research eastern part of the Gerede segment of the North Anatolian Fault: Pheliminary results of İsmetpaşa trench]. In: AKYÜZ, H. S. & BARKA, A.A. (eds), Aktif Tektonik Araştırma Grubu Birinci Toplantısı, ATAG-1, Makaleler. İstanbul Technical University-Institute of Eurasian Earth Sciences, İstanbul, 88-94 [in Turkish].
  • ÖZÇELİK, Y. 1994. Tectono-stratigraphy of the ,Laçin Area (Çorum-Turkey). MSc Thesis, Middle East Technical University, 133 p [unpublished].
  • ÖZTÜRK, A. 1968. Çerkeş-Eskipazar-Gerede Bölgesinin Jeolojisi [Geology of the Çerkeş-Eskipazar-Gerede Region]. PhD Thesis, Ankara University, [unpublished, in Turkish].
  • ÖZTÜRK, A., İNAN, S. & TUTKUN, Z. 1984. Abant ile Yeniçağa arasında Kuzey Anadolu fay zonu [North Anatolian Fault Zone in the area between Abant and Yeniçağa]. Cumhuriyet University, Faculty of Engineering, Journal of Earth Sciences 1, 1-18 [in Turkish].
  • PINAR, N. 1953. 13 Ağustos 1951 Kurşunlu depreminin jeolojik ve makrosismik etüdü [Geological and macroseismology of the 13 August 1951 Kurşunlu earthquake]. İstanbul Üniversitesi Fen Fakültesi Dergisi, Seri A XVIII, 131-141 [in Turkish].
  • REILINGER, R. E., MCCLUSKY, S. C, ORAL, M. B., KING, R. W. & TOKSÖZ, M. N. 1977. Global positioning system measurements of present-day crustal movements in the Arabia-Africa-Eurasia plate collision zone. Journal of Geophysical Research 102, 9983-9999.
  • SLYVESTER, A.G. 1988. Strike-slip faults. Geological Society of American Bulletin 100, 1666-1703.
  • SOYSAL, H., SİPAHIOĞLU, S., KOÇAK, D. & ALTINOK, Y. 1981. Türkiye ve Çevresinin Tarihsel Deprem Katalogu (M.Ö. 2100-M.S. 1900) [A Histotical Earthquake Catalogue for Turkey and its Surrounding -2100 BC to 1900]. Scientific and Technical Research Council of Turkey Project, No. TBAG 341, 87 p [unpublished, in Turkish].
  • STEIN, R.S., BARKA, A. & DIETERICH, J.H. 1997. Progressive failure on the North Anatolian fault since 1939 by earthquake stress triggering. Geophysical Journal International 128, 594-604.
  • ŞAROĞLU, F., EMRE, Ö. & BORAY, A., 1987. Türkiye'nin Diri Fayları ve Depremsellikleri [Active Faults of Turkey and Their Seismicity]. Mineral Research and Exploration Institute of Turkey Report 8174, 394 p [unpublished, in Turkish].
  • ŞAROĞLU, F. 1988. Age and offset of the North Anatolian fault. MEW Journal of Pure and Applied Sciences 21, 65-79.
  • ŞENGÖR, A.M.C. & BARKA, A. 1992. Evolution of escape-related strike-slip systems; implications for distribution of collisional orogens. 29th International Geological Congress, Kyoto, Japan, Abstracts 1, 232.
  • TAŞMAN, C. E. 1944. Gerede-Bolu depremi [Gerede-Bolu earthquake]. Mineral Research and Exploration Intitute of Turkey Bulletin 1/31, {PAGES?} Ankara [in Turkish].
  • TATAR, Y. 1978 Kuzey Anadolu fay zonu'nun Erzincan-Refahiye arasındaki bölümü üzerinde tektonik incelemeler [Tectonic studies on the North Anatolian Fault Zone in the area between Erzincan and Refahiye]. Hacettepe University, Earth Sciences 4, 201-236 [in Turkish].
  • TAYMAZ, T., EYİDOĞAN, H. & JACKSON, J. 1991. Source parameters of large earthquakes in the East Anatolian fault zone (Turkey). Geophysical Journal International 106, 537-550.
  • TAYMAZ, T. 2000. 6 Haziran 2000 Orta-Çankırı Depremi (Mw= 6.0) ve çevresinin depremselliği: Kuzey Anadolu fayı'nın deprem potansiyeli ve fay düzlemi çözümleri [6 June 2000 Orta-Çankırı Earthquake - Mw= 6.0 - and seismicity of surrounding area: Earthquake potential of the North Anatolian fault and fault plane solutions]. Aktif Tektonik Araştırma Grubu Dördüncü Toplantısı, 16-17 Kasım 2000, Eskişehir, Abstracts, p. 7 [in Turkish].
  • TOKAY, M. 1973. Kuzey Anadolu fay zonu'nun Gerede ile İlgaz arasındaki kısmında jeolojik gözlemler [(Geological observations on the North Anatolian fault zone in the area between Gerede and İlgaz]. Kuzey Anadolu Fayı ve Deprem Kuşağı Simpozyumu, 29-31 Mart 1972, Ankara, 12-29 [in Turkish].
  • TOKAY, M., ÖZTÜRK, A. & KOÇYİĞİT, A. 1973. Arkotdağ Formasyonu'nun Litolojisi, Kökeni ve Kuzey Anadolu Fay Zonu ile Muhtemel Bağlantısı [Lithlogy and Origin of the Arkotdağ Formation and Its Relation to the North Anatolian Fault Zone]. Scientific and Technical Research Council of Turkey Project, No. TBAG 43, 53 p [unpublished, in Turkish].
  • TÜRKECAN, A., HEPŞEN, N., PAPAK, I., AKBAŞ, B., DİNÇEL, A., KARATAŞ, S., ÖZGÜR, B.L., AKAY, E., BEDRİ, Y., SEVİN, M., MUTLU, G., SEVİN, D., ÜNAY, E. & SARAÇ, G. 1991. Seben-Gerede (Bolu)-Güdül-Beypazarı (Ankara) ve Çerkeş-Orta-Kurşunlu (Çankırı) Yörelerinin (Köroğlu Dağlan) Jeolojisi ve Volkanik Kayaçlarının Petrolojisi [Geology of Seben-Gerede (Bolu)-Güdül-Beypazarı (Ankara) ve Çerkeş-Orta-Kurşunlu (Çankırı) Regions (Köroğlu Mountains) and Petrology of Volcanic Rocks]. Mineral Research and Exploration Institute of ' Turkey Report, No. 9193, 118 p [unpublished, in Turkish].
  • WESTAWAY, R. & ARGER, J. 2001. Kinematics of the Malatya-Ovacik fault zone. Geodinamica Acta 14, 103-131.
Turkish Journal of Earth Sciences-Cover
  • ISSN: 1300-0985
  • Yayın Aralığı: Yılda 6 Sayı
  • Yayıncı: TÜBİTAK
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