İzmir körfezi ve dolaylarının aktif tektonizmasının sismik yansıma verileri ile incelenmesi

To investigate the active tectonism of İzmir Gulf and offshore Alaçatı-Doğanbey-Kuşadası, 975 km multi-channel and single-channel seismic reflection profiles collected and processed. Data show that the study area is widespread occupied by N-S to NE-SW trending master faults characterized as strike-slip faults with generally compression component, reverse faults and secondary E-W trending normal faults. These faults are also very compatible with the active faults of surrounding onland area. While the outer part of İzmir gulf is controlled by N-S oriented Karaburun reverse fault, the Seferihisar horst at the southern offshore area is bordered by NE-SW oriented strike-slip Tuzla fault zone with positive flower character. The direction of the Karaburun fault changes from NNW-SSE to N-S along the eastern coast of Karaburun Peninsula with accompanying a change in its fault type from positive flower structure to reverse fault. Also, Tuzla fault zone is observed offshore Doğanbey Promontory with mostly reverse fault component on the seismic sections where its orientation changes from NE-SW to N?S.  On the other hand, the inner part of the gulf is deliniated by E-W trending İzmir normal fault. Development of active fault patterns in the study area is explained by the prevention of westward motion of Anatolia by Greece, the occurrence of a compression between them, counter-clock wise rotation and SW motion and NE-SW extension of Anatolia towards to the Hellenic arc. Keywords: Active tectonism, Western Anatolia, strike-slip faulting, İzmir gulf, seismic reflection.İzmir Körfezi, Alaçatı-Doğanbey-Kuşadası açıklarının aktif tektonizmasını incelemek amacıyla toplanan ve işlenen 975 km uzunluğundaki çok ve tek  kanallı sismik yansıma kesitlerinden  bölgede  birincil K-G  ve KD-GB gidişli genellikle sıkışma bileşenli aktif doğrultu atımlı fay sistemleri, ters faylar ve ikincil D-B gidişli normal faylar haritalanmıştır. Körfezin KKB-GGD gidişi Karaburun ters fayı ile sınırlanırken, güneyde Seferihisar yükselimi KD-GB doğrultulu Tuzla fayı kontrolündedir. Körfezin D-B uzanan iç kısmını güneyde İzmir normal fayı sınırlar. Bölgedeki aktif fay sistemlerinin gelişimi batıya kaçan Anadolu'nun Yunanistan engeli sonucu saatin tersi yönünde dönüşü ve Hellen yayına doğru GB hareketi sonucu oluşan kabaca D-B sıkışma, KD-GB gerilme rejimi ile açıklanmaktadır. Anahtar Kelimeler: Aktif tektonik, Batı Anadolu, doğrultu atımlı faylanma, İzmir Körfezi, sismik yansıma

The Continuation of the North Anatolian Fault within the Sea of Marmara

Marmara Denizi’nde toplanmış olan 2200 km’lik çok-kanallı sismik yansıma hatlarının değerlendirilmesi esnasında, kuzey çukurluklarını örten çok ışınlı derinlik verisinden faydalanılmıştır. Çok-kanallı sismik yansıma verileri İTÜ Jeofizik Mühendisliği Bölümü Nezihi Canıtez Veri İşlem Laboratuvar’ında Disco-Focus yazılım paketi ile işlenmiştir. Marmara Denizi’nin kuzey kesiminin şu anda sürekli faal doğrultu-atımlı bir fay sistemi ile kesildiği sonucuna ulaşılmıştır ve bu fay, Marmara Fayı olarak adlandırılmıştır. Marmara Fayı, Marmara Denizi doğusundaki 270°’lik İzmit Fayı’nı, denizin batısındaki 245°’lik Ganos Fayı’na bağlar. Marmara Fayı iki ana doğrultuya sahiptir. Fay, Marmara Denizi’nin 2/3’lük batı kısmında 130 km uzunluğunda ve 265° yönünde uzanırken, doğu kısmında ise 70 km’nin üzerinde 295° doğrultusunda uzanmaktadır.Anahtar Kelimeler: Marmara Denizi bölgesi, faal faylar, çok kanallı yöntemler, sismik, derinlik bilgisi.We analyze 2200 km of multi-channel seismic reflection profiles that have become recently available in the Sea of Marmara. This analysis benefits from the recent acquisition of multi-beam bathymetric data covering the axial portion of the northern basins. We conclude that the northern Sea of Marmara is at present cut by an active continuous strike-slip fault system, that we call the Marmara Fault. It links the 270° İzmit portion of the northern branch of the North Anatolian Fault to the east of the sea to the 245° Ganos Fault to the west. The Marmara Fault which is the continuation of the Ganos Fault in the Sea of Marmara with the 265° extent and approximately 130 km length is followed as a fault offset the Tekirdağ Basin, Western High, Central Basin and Central High. At the northeastern extremity of the Sea of Marmara, it turns southeast toward the northern margin of the Çınarcık Basin. It extends about 70 km in a 295° direction in the Çınarcık Basin. There is thus a 25° clockwise rotation with respect to the 270° İzmit Fault strand that should result in a slight extensional component. Certainly when it is called Marmara Fault, it should be considered the Marmara Fault Zone (MFZ) at the same time. The corridor that followed by microearthquake activity in the Sea of Marmara is the seismological evidence that also support the Marmara Fault Zone term.Keywords: Sea of Marmara region, active faults, multichannel methods, seismics, bathymetry

An environmentally-friendly integrated seismic imaging for coal exploration in the Miocene Soma Basin, Western Turkey

Seismic reflection data from target depths of several hundred metres have been acquired and processed as an aid for lignite exploration in the Miocene Soma Basin, western Turkey. An environmentally-friendly approach was followed by acquiring the data with mini-vibroseisseismic source along crooked lines, using available mountain/forest and village roads; quality control tests were conducted to determine optimal field parameters that would yield dataset with best signal-to-noise (SN) ratio prior to real data acquisition; and stratigraphic interfaces giving rise to reflection events in the seismic data were identified from the vertical seismic profiling (VSP). Stacked seismic sections were successfully correlated with geological cross-sections drawn based on available borehole data. Thus, it is shown that decreasing time and the cost for coal exploration is possible by utilising surface and VSP. Environment friendly approach of the seismic method applied in this study is also beneficial in regard to environmental concerns