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Öğe 02.03.2017 and 24.04.2018 Samsat (Adiyaman) Earthquakes and Their Importance in Regional Seismotectonics(TMMOB JEOLOJI MUHENDISLERI ODASI, 2019) Tatar, Orhan; Kocbulut, Fikret; Polat, Ali; Demirel, MehmetIn this study, Synthetic Aperture Radar Interferometry (InSAR) method is used together with field observations to determine whether surface deformations occur in the region after the 5,5 Mw (AFAD) Samsat Earthquake occurred at a distance of 2.5 km from the Samsat district of Adiyaman province on 2 March 2017. We attempted to determine the deformation of the interferogram created by analyzing two Synthetic Aperture Radar (SAR) images of the Sentinel-1A fit before and after the earthquake. As a result of the evaluation of the interferogram, a surface deformation of about 2.5 cm in the satellite view direction/Line of Sight (LoS) was observed in the region. This deformation is mostly concentrated in the northeast of Samsat town. As a result of the detailed field investigations made immediately after the earthquake in the region, no surface rupture occurred but surface deformations in the form of local and discontinous fissures developed in some areas. It is understood that the Earthquake developed on a fault passing through about 5 Km North of Samsat and named as Samsat Fault by TPAO. It appears that more than 400 aftershocks following the main shock in the region concentrate roughly on a N40-50W lineament. It is noteworthy that in the observations made in the field, the distribution of the damage has also developed along this line in particular.Öğe 02.03.2017 ve 24.04.2018 Samsat (Adıyaman) Depremleri ve Bölgesel Sismotektonik İçindeki Önemi(2019) Tatar, Orhan; Koçbulut, Fikret; Polat, Ali; Demirel, MehmetBu çalışmada, 2 Mart 2017 tarihinde saat 14.06’da Adıyaman ili Samsat ilçesine 2.5 km uzaklıkta, yerin yaklaşık10 km derinliğinde meydana gelen 5.5 Mw büyüklüğündeki depremin bölgede yüzey deformasyonları oluşturupoluşturmadığı, Yapay Açıklık Radar İnterferometrisi (InSAR) yöntemi ve arazi gözlemleriyle incelenmiştir. Depremöncesi ve deprem sonrasına ait Sentinel-1A uydusunun iki yapay açıklık radarı (SAR) görüntüsü analiz edilerekoluşturulan interferogramdan deformasyon belirlenmeye çalışılmıştır. Interferogramın değerlendirilmesi sonucundabölgede uydu bakış yönünde (LoS) yaklaşık 2.5 cm civarında bir yüzey deformasyonunun meydana geldiğigözlenmiştir. Bu deformasyon daha çok Samsat ilçesi yakın kuzeydoğusunda yoğunlaşmıştır. Bölgede depreminhemen sonrasında yapılan ayrıntılı saha incelemeleri sonucunda ise herhangi bir yüzey kırığının oluşmadığı, bunakarşın bazı alanlarda yersel çatlaklar şeklinde yüzey deformasyonlarının geliştiği saptanmıştır. Depremin, Samsatİlçesinin yaklaşık 5 km kuzeyinden geçen ve TPAO tarafından Samsat Fayı olarak adlandırılan fay üzerinde geliştiğianlaşılmaktadır. Ana şok sonrası bölgede meydana gelen 400’ü aşkın artçı sarsıntının kabaca K40-50B gidişli birçizgisellik üzerinde yoğunlaştığı görülmektedir. Sahada yapılan gözlemlerde de hasar dağılımının özellikle bu hatboyunca geliştiği dikkat çekicidir.Öğe Anatomy of a Landslide: Evaluation of the Importance of Basic Geological Investigations as exemplified in the Kuzulu (Koyulhisar - Sivas, Türkiye) Landslide of 17 March 2005(Tmmob Jeoloji Muhendisleri Odasi, 2024) Guersoy, Halil; Tatar, Orhan; Mesci, Bekir Levent; Canbaz, Oktay; Polat, Ali; Akpinar, ZaferOn 17 March 2005, a large and complex landslide occurred west of Koyulhisar (Sivas, Turkey). This landslide, mostly comprising debris derived from volcanic rocks and mud flow, moved over the Kuzulu settlement area in the valley in a very short time and 15 people were killed. The Kuzulu landslide zone is not a simple mass movement limited to a single movement. Instead, complexities are introduced by the regional topographic structure and location of the crown and heel zone so that at least 4 other large flow movements occurred in this region between 17 March 2005 and August 2007. One of the most important factors initiating and accelerating this landslide has been the influence of surface and groundwater seepage from melting snow. This seepage has followed the dense pattern of discontinuities and normal fault planes observed in and around the crown region. These waters saturated the profoundly altered volcanic bedrocks with water, and as a result, a slip surface developed between the underlying limestone and weathered volcanic rocks. This was responsible for the catastrophic mass movement. To correctly interpret the causes and consequences of mass movements, where the movement speeds and directions can be monitored in detail using the advanced technological tools available today, detailed geological mapping is essential. There are currently differing interpretations of the development and triggering factors responsible for the Kuzulu landslide. This is primarily because the geological and tectonic structure of the landslide zone and its surroundings have not hitherto been investigated in the necessary detail. In this study, a detailed new geological map revealing the basic geological features of the region has been compiled and the characteristics of the landslide re-evaluated for comparison with previous studies. With the help of Digital Elevation Model (DEM) maps created from the satellite images of the Kuzulu Landslide area before and after the landslide, a total volumetric movement of 10.367.766 m 3 is estimated to have occurred. We calculate that a net 9,372,880 m 3 of material flowed from the area within the landslide boundary. Any assessments of ground suitable for settlement with a view to urban development and planning requires a proper understanding of the geomorphological structure of the surrounding region and the engineering geological properties of the ground. The fact that Koyulhisar district centre is located both in the immediate vicinity of an active fault zone such as KAFZ and on an active landslide area emphasises this issue. Detailed geological, geomorphological, landslide susceptibility, hazard and risk maps are of great importance to prevent or mitigate the damaging consequences of earthquakes and the landslides that they may be motivated.Öğe Crustal deformation and kinematics of the Eastern Part of the North Anatolian Fault Zone (Turkey) from GPS measurements(ELSEVIER SCIENCE BV, 2012) Tatar, Orhan; Poyraz, Fatih; Gursoy, Halil; Cakir, Ziyadin; Ergintav, Semih; Akpinar, Zafer; Kocbulut, Fikret; Sezen, Fikret; Turk, Tarik; Hastaoglu, Kemal O.; Polat, Ali; Mesci, B. Levent; Gursoy, Onder; Ayazli, I. Ercument; Cakmak, Rahsan; Belgen, Alpay; Yavasoglu, HakanThe North Anatolian Fault Zone (NAFZ) is a 1200 km long dextral strike-slip fault zone forming the boundary between the Eurasian and Anatolian plates. It extends from the Gulf of Saros (North Aegean) in the west to the town of Karliova in eastern Turkey. Although there have been numerous geodetic studies concerning the crustal deformation, velocity field and the slip rate of the NAFZ along its western and central segments, geodetic observations along the eastern section of the NAFZ are sparse. In order to investigate the GPS velocities and the slip rate along the eastern part of the NAFZ, a dense GPS network consisting of 36 benchmarks was installed between Tokat and Erzincan on both sides of the fault zone and measured from 2006 to 2008. Measurement results indicate that the slip rate of the NAFZ increases westwards within about 400 km from 16.3 +/- 2.3 mm/year to 24.0 +/- 2.9 mm/year, in consistence with the observation that the Anatolian block is being pulled by the Hellenic trench rather than being pushed by the Arabian plate as a result of continental collision between the Arabian and Eurasian plates in eastern Turkey since late Miocene. Modelling the GPS velocities shows that fault locking depth increases also in the same direction from 8.1 +/- 3.3 km to 12.8 +/- 3.9 km. Slip rate decreases as moving off the Hellenic trench. An average slip rate of 20.1 +/- 2.4 mm/year and a locking depth of 12.5 +/- 3.5 km are also estimated for the entire study area by using all of the GPS measurements obtained in this study. The GPS velocities are in good agreement with the kinematic models created by paleomagnetic studies in the region and complete the overall picture. (C) 2011 Elsevier B.V. All rights reserved.Öğe Kuzey Anadolu fay zonunun Suşehri havzasındaki bölümünün neotektonik ve paleosismolojik özellikleri(Cumhuriyet Üniversitesi, 2011) Polat, Ali; Tatar, OrhanBu çalışmada, Suşehri Havzası'nın güncel tektonik yapısının araştırılması amaçlanmıştır. İnceleme alanı coğrafik konum olarak Sivas ilinin yaklaşık 130 km kuzey doğusunda, Suşehri ve Gölova ilçeleri arasında kalan alanı kapsamaktadır. Türkiye'de deprem üreten en önemli aktif faylardan biri olan Kuzey Anadolu Fay Zonu (KAFZ) içerisinde yer alan çalışma alanı, bu konumundan dolayı günümüze kadar çeşitli araştırıcılar tarafından çalışılmıştır. Havzanın evrimsel modeli, depremselliği ve KAF'nın bu bölgedeki atımı en çok çalışılan konular arasındadır.Bu çalışmada Gölova- Suşehri arasında kalan bölge güncel yöntemler ile çalışılmış ve havzanın modeli ile ilgili yeni yaklaşımlarda bulunulmuştur Jeofizik yöntemlerden Yeraltı Radarı (GPR) ve Manyetik yöntem kullanılarak havza içerisinde yer alan gömülü faylar saptanmıştırFay haritalamalarında arazi çalışmalarına büyük katkı sağlayan 60 cm çözünürlüklü Quickbird uydu görüntüleri kullanılmıştır. Bunun yanı sıra 1939 Erzincan depremi yüzey kırığı ayrıntılı olarak haritalanmış ve kırık üzerinde 3 adet fay kazısı (Trench) açılmıştır.İnceleme alanının 1/25000 ölçekli neotektonik haritası hazırlanarak güncel tektonik yapılar haritalanmıştır. Fay topluluklarının kinematik analizi yapılarak, günümüzde etkin olan rejimin doğrultu atımlı fay sistemi olduğu görülmüştür. Doğrultu atımlı faylanmayı oluşturan gerilme rejiminin KB-GD doğrultulu sıkışma rejimi altında geliştiği belirlenmiştir. Doğrultu atımlı faylanmanın yanı sıra, bu havza içerisinde, normal faylar ve verev atımlı normal faylar da gözlenmiştir. Açılma rejimiyle ilişkili olan bu fayların KKD-GGB ve KD-GB yönlü açılma rejimiyle oluştukları sonucuna varılmış olup, aynı zamanda bu faylanmanın bir doğrultu atımlı fay kontrolü altında gelişen Suşehri Havzası'nın oluşmasında da etkin oldukları düşünülmektedir.Bu çalışmalar sonucunda Havzanın evrimsel modeli ile ilgili; havzanın ilk açılmaya başladığı dönemde fay kaması havzası olarak geliştiği ve daha sonra KAF'ın sağa sıçrama yaparak, bir çek ayır havza olarak çalışmaya başladığı ve günümüze kadar geldiği şeklinde bir sonuca varılmıştır.Anahtar kelimeler: Suşehri Havzası, Gölova, Kuzey Anadolu Fay Zonu, Neotektonik, GPR Yöntemi, Manyetik Yöntem, Fay Kinematiği, Fay Kaması Havzası, Çek-Ayır Havza.Öğe Kızılırmak fay zonunun Şarkışla kuzeyinde Ağcakışla-Kalecik arasında kalan kesiminin neotektonik özellikleri(Cumhuriyet Üniversitesi, 2005) Polat, Ali; Tatar, Orhanin ÖZET Yüksek Lisans Tezi Kızılırmak Fay Zonunun Şarkışla Kuzeyinde Ağcakışla-Kalecik Arasında Kalan Kesiminin Neotektonik Özellikleri AIİPOLAT Cumhuriyet Üniversitesi Fen Bilimleri Enstitüsü Jeoloji Mühendisliği Anabilim Dalı Danışman: Prof.Dr. Orhan TATAR Bu çalışma kapsamında Orta Anadolu Fay Zonu'nun Şarkışla kuzeyinde, Kızılırmak vadisi boyunca Ağçakışla, Kalecik ve Kaymak köyleri arasında kalan bölümünün tektonomorfolojik özelliklerinin incelenmesi amaçlanmıştır. Bilindiği üzere Orta Anadolu Fay Zonu üzerinde son yıllarda ayrıntılı çalışmalar yapılmakta olup, özellikle deprem üretme potansiyeli açısından dikkat çekmektedir. Bu çalışma aynı zamanda bölgenin genel sismotektonik özelliklerinin incelenmesi açısından da önem taşımaktadır. Bu amaca yönelik yapılan çalışma arazi, laboratuar ve büro çalışmaları olarak üç aşamada gerçekleştirilmiştir. Sivas î 36 c3, 1 36 c4, J 36 bl ve J 36 b2 paftalarını içeren inceleme alanının 1/25.000 ölçekli jeoloji haritası hazırlanmıştır. Araziden alman kayaç örneklerinin ayrıntılı paleontolojik ve petrografik incelemeleri yapılmış ve bölgenin stratigrafîk özellikleri ortaya konulmuştur. Neotektonik dönemde oluşan kaya birimleri içerisinde ayırtlanan Pliyosen-Pleyistosen yaşlı Hardal bazaltının ayrıntılı haritalaması yapılarak diğer birimlerle ilişkisi net olarak ortaya konmuştur.IV Arazide yapılan gözlemler sonucunda inceleme alanın morfotektonik özellikleri incelenerek çizgisellikler saptanmıştır. Çalışma alanını da kapsayan daha geniş bir alanda son yıllarda meydana gelen deprem verileri derlenmiş ve depremlerin odak noktalan inceleme alanının 3 boyutlu (DEM) haritası üzerine yerleştirilmiştir. Bu depremlerin inceleme alam ve yalan çevresindeki çizgiselliklerle paralellik sundukları gözlenmiştir. İnceleme alanındaki çizgisellikler daha çok morfolojik olarak belirgindir. Bölgenin üç boyutlu (DEM) haritaları üzerinde ve arazi gözlemleri sonucunda özellikle Kızılırmak nehrinin doğu kenarı boyunca gelişen çizgiselliklerin varlığı ortaya çıkarılmıştır. Bu veriler inceleme alanının kuzeydoğusunda KD-GB uzantılı doğrultu atımlı fay morfolojisini işaret etmektedir. Ayrıca inceleme alanının GB'sında Kızılırmak nehrine yaklaşık koşut olarak gelişmiş normal faylanmalar da belirlenmiştir. Anahtar Kelimeler: Ağçakışla, Jeomorfoloji, Kızılırmak Fay Zonu, Neotektonik, Orta Anadolu Fay Zonu, Şarkışla.Öğe New observations on the 1939 Erzincan Earthquake surface rupture on the Kelkit Valley segment of the North Anatolian Fault Zone, Turkey(PERGAMON-ELSEVIER SCIENCE LTD, 2013) Gursoy, Halil; Tatar, Orhan; Akpinar, Zafer; Polat, Ali; Mesci, Levent; Tuncer, DoganThe 1939 Erzincan Earthquake (M=7.8), occurred on the North Anatolian Fault Zone (NAFZ), was one of the most active strike-slip faults in the world, and created a 360-km-long surface rupture. Traces of this surface rupture are still prominently observed. In the absence of detailed mapping to resolve the fault characteristics, detailed observations have been conducted at 20 different points on the 70-km-long Kelkit Valley Segment (INS) of the NAFZ's between Niksar and Koyulhisar. Field data defining fault character and slip amounts were found at eight points and show right-lateral slip varying between 1.8 and 4.25 m and the vertical slip varying between 0.5 and 2.0 m. The KVS developed in the most morphologically prominent and narrowest part of the NAFZ. Therefore, the chances of finding evidence of more than one historical earthquake in trenches opened to investigate palaeoseismological aspects are higher. Faults observed in foundation and channel excavations opened for energy purposes in the Resadiye region show this clearly and evidence for up to four seismic events including the 1939 Erzincan Earthquake have been discovered. Further studies are required to discover whether right-lateral deformation on at some locations on this segment is surface ruptures associated with the 1939 earthquake or later creep. Crown Copyright (C) 2012 Published by Elsevier Ltd. All rights reserved.Öğe Palaeomagnetic evidence for the neotectonic evolution of the Erzincan Basin, North Anatolian Fault Zone, Turkey(PERGAMON-ELSEVIER SCIENCE LTD, 2013) Tatar, Orhan; Akpinar, Zafer; Gursoy, Halil; Piper, John D. A.; Kocbulut, Fikret; Mesci, B. Levent; Polat, Ali; Roberts, Andrew P.Ongoing motion of Anatolia towards the west is caused by convergence of the Arabian and Eurasian plates coupled with suction towards the retreating Hellenic Arc. This regime is controlling the development of neotectonic structures in Turkey with the resulting distributed deformation accommodated primarily between the East and North Anatolian Intracontinental Transform Faults. The Erzincan Basin is developed along the eastern part of the latter fault and although it incorporates one of the largest Quaternary basins in Turkey, the duration and tectonic evolution are disputed. Tectonic models proposed to explain the basin range from simple rhomboidal pull-apart to a complex multi-phase evolution. To help constrain the age and tectonic regime(s) forming the basin we have conducted a palaeomagnetic and geochronologic study of volcanic domes which occur mainly in proximity to strike-slip faulting along the northern margin of the basin. The investigated sample comprises 27 lava sites located within 14 cones, 13 to the north and one in the south. Although difficult propositions for palaeomagnetic investigation because the young predominantly-pyroclastic constructive topography is susceptible to collapse, all sites show positive inclinations and mainly northerly declinations showing that they are the consequence of a tectonic regime confined to the Brunhes Chron. Whilst the limitation of directional data from these young constructive features is stressed, ten cones are found to show clockwise rotations ranging from 12 degrees to 195 degrees with three cones showing no significant rotation. Geochronological studies from 13 samples yield a range of ages with 6 providing meaningful results <0.3 Myr in age and consistent with young ages evident from morphology and paleomagnetism. AMS (Anisotropy of Magnetic Susceptibility) studies identify a fabric related to downslope flow at most sites with the majority moving away from conduits controlled by fractures paralleling the dominant NW-SE trend of the master fault. The palaeomagnetic and geochronologic results show that the history of the Erzincan Basin has involved at least two phases with the later phase incoporating an extensional component permitting access to mantle melts and confined to the last similar to 300,000 years. The earlier phase commenced in Late Miocene or Early Pliocene times and initiated the rift infill which currently attains a maximum thickness in excess of 2.7 km. We propose that the Erzincan Basin is now segmented as a mature basin by strike-slip cross faults although these cannot explain the consistent clockwise rotations observed within the small blocks incorporating the volcanic cones because these are confined to a narrow zone between two master faults and appear to be subject to ball-bearing style rotation. (C) 2012 Elsevier Ltd. All rights reserved.Öğe Paleoseismological Findings on the Ortakoy-Susehri Segment of the 1939 Erzincan Earthquake Surface Rupture, North Anatolian Fault Zone(Tmmob Jeoloji Muhendisleri Odasi, 2012) Polat, Ali; Tatar, Orhan; Gursoy, Halil; Karabacak, Volkan; Zabci, Cengiz; Sancar, TaylanThe study area is located within the Susehri-Golova basin on eastern part of the North Anatolian Fault Zone (NAFZ). Great devastating earthquakes have been occurred on this highly active seismic fault zone in near historical period. The last great earthquake causing loss of many life and properties was occurred on 27 December 1939 in Erzincan along the eastern part of the NAFZ. This earthquake has created hundreds of kilometers surface rupture, and can also be traced in the study area. Significant information is obtained by early paleoseismological studies carried out especially on the middle and western parts of the NAFZ proving important data about earthquake return periods and magnitudes of seismic activity in the period. Paleoseismological studies on eastern part of the NAFZ are less than western part of the NAFZ. In this study, three trenches were excavated on the 1939 Erzincan earthquake surface rupture. These trenches are located from west to east, in Eskibag, Asagiyenikoy and Asagitepecik villages. Eskibag trench was excavated on a sag pond to the southeast of Sevindik and northeast of Eskibag villages. Asagi Tepecik trench was excavated on the same lineament to the northeast of Asagiyenikoy where a clear fault morphology is observed. The Asagi Tepecik was excavated 2.5 km southeast of the Lake Sut. These trench data are significant because of showing data of large earthquakes repeated during Holocene times. Beside the fact that 1939 surface rupture was observed, the earthquake ruptures formed before 1939 were also observed on trench logs. It is showed that 1939 earthquake surface rupture follows older ruptures and reveals the existence of several different seismic activities prior to 1939 earthquake.Öğe Two-phased evolution of the Susehri Basin on the North Anatolian Fault Zone, Turkey(TAYLOR & FRANCIS LTD, 2012) Polat, Ali; Tatar, Orhan; Gursoy, Halil; Yalciner, C. Caglar; Buyuksarac, AydinThis study has aimed to evaluate the current tectonic structure of the Susehri Basin located on the eastern part of the North Anatolian Fault Zone (NAFZ), one of the most important active faults in Turkey. The work extends earlier investigations of offset and seismicity on the NAFZ and tests a range of evolutionary models. In this study, buried faults have been determined from Ground penetrating radar and magnetic anomalies and possible discontinuities identified by interpolating these data in a region between Golova and Susehri. The discontinuities are shown to be linked to negative flower structures formed within the strike-slip fault zone. Quickbird satellite images have been used to map faults and produce kinematic analyses which show that the active stress regime is dominantly strike-slip. However, normal faults and oblique-slip faults are also observed in the basin together with strike-slip faults and the stress regime creating the strike-slip faults is shown to have formed under NW-SE directed transtension. In addition, oblique faults formed under an extensional regime with NNE-SSW direction also occur in the Susehri Basin as subsets formed under the constraining strike-slip regime. We conclude that the Susehri Basin started to grow as a fault wedge basin following which it transformed into a pull-apart basin by a south splay on the NAFZ so it is now dominantly a transtensional pull-apart feature.
