Istanbul Bogazi, bir akarsu vadisinin tektonik olarak evrimlestigi dar bir kanaldir ve evrimi sir... more Istanbul Bogazi, bir akarsu vadisinin tektonik olarak evrimlestigi dar bir kanaldir ve evrimi sirasinda bogaz kanalinin icerisine kalin bir cokel istif depolanmistir. Ayrintili sismik ve batimetrik inceleme, gunumuz bogaz tabani sekillenmesinde uc onemli faktorun etkisini gosterir. Bu etkenler; deniz tabaninda yaygin bir asinim, agirlikli olarak sediman suruklenmeleri ve kitle hareketleri olarak izlenen birikim ve faylanma olarak gozlenmektedir. Deniz tabani sekillenmesini en etkin olarak denetleyen asinim etkisi kendisini, bogaz cokellerinin ust bolumunu olusturan paralel tabakali istifin yayginca erozyona ugramis olmasi ile gostermektedir. Soz konusu asinim yuzeyi, gunumuzde onemli olcude Istanbul Bogazi deniz tabanini olusturur. Asinmaya ugramis olan cokel miktari ise, yaklasik olarak 2x108 m3 olarak hesaplanmistir. Sismik veri uzerinde belirlenen asinim miktari ve deniz tabani morfolojisi, soz konusu asinmayi olusturan akintinin guneyden kuzeye dogru gelistigini gostermektedir. ...
ABSTRACT Although there are many research studies on the northern and southern branches of the No... more ABSTRACT Although there are many research studies on the northern and southern branches of the North Anatolian fault, cutting through the deep basins of the Sea of Marmara in the north and creating a series of pull-apart basins on the southern mainland, little data is available about the geometrical and kinematical characteristics of the middle strand of the North Anatolian fault. The first detailed geometry of the middle strand of the North Anatolian fault along the southern Marmara shelf, including the Gemlik and Bandırma Bay, will be given in this study, by a combined interpretation of different seismic data sets. The characteristic features of its segments and their importance on the paleogeographic evolution of the southern shelf sub-basins were defined. The longest one of these faults, the Armutlu-Bandırma segment, is a 75-km long dextral strike-slip fault which connects the W–E trending Gençali segment in the east and NE–SW trending Kapıdağ-Edincik segment in the west. In this context, the Gemlik Bay opened as a pull-apart basin under the control of the middle strand whilst a new fault segment developed during the late Pleistocene, cutting through the eastern rim of the bay. In this region, a delta front forming the paleoshoreline of the Gemlik paleolake was cut and shifted approximately 60 ± 5 m by the new segment. The same offset on this fault was also measured on a natural scarp of acoustic basement to the west and integrated with this paleoshoreline forming the slightly descending topset–foreset reflections of the delta front. Therefore the new segment is believed to be active at least for the last 30,000 years. The annual lateral slip rate representing this period of time will be 2 mm, which is quite consistent with modern GPS measurements. Towards the west, the Bandırma Bay is a rectangular transpressional basin whilst the Erdek Bay is a passive basin under the control of NW–SE trending faults. When the water level of the paleo-Marmara lake dropped down to −90 m, the water levels of the suspended paleolakes of Bandırma and Gemlik on the southern shelf were −50.3 (−3.3 Global Isostatic Adjustment—GIA) and −60.5 (−3.3 GIA) m below the present mean sea level, respectively. As of today a similar example can be seen between the Sea of Marmara and the shallow freshwater lakes of Manyas and Uluabat. Similarly, the paleolakes of Gemlik and Bandirma were affected by the water level fluctuations at different time periods, even though both lakes were isolated from the Sea of Marmara during the glacial periods.
ABSTRACT In general, potential field data are noisy due to the surveys in rugged topography. Stan... more ABSTRACT In general, potential field data are noisy due to the surveys in rugged topography. Standard reduction techniques are not fully adequate to eliminate this problem. Most of the interpretation techniques require the observations measured on the horizontal surface. Furthermore, upward and downward continuations, vertical derivatives can improve the ambiguity in the potential field data. In present, there are methods for the application of the analytical continuations and derivatives, but these are not successful enough due to technical restrictions and unwanted edge effects. In this paper, an easy and efficient technique known as the equivalent source is applied to the observations made over the rugged topography. Presented method is tested on synthetic example using an anomaly of a sphere located below the synthetic topography. At first, our method is applied only to obtain topographic distortion corrected map by moving forward windowed parts of the area. Afterwards, analytic continuations of the topographic distortion corrected map are obtained. Finally, vertical derivative map is obtained from the analytic continuations of the topographic distortions corrected map. Amplitudes are controlled along profiles on top of theoretical and calculated spheres. A good correlation can be observed from the amplitude values. This method is also applied to the field data. The second vertical derivative map is produced from the topographic distortion corrected and 5 km upward continued gravity map of the region. We note that by the interpretations identified faults in these map are in good agreement with the faults shown in the structural map of the region.
Επιστημονική Επετηρίδα του Τμήματος Γεωλογίας (Α. Π. Θ.), 2010
Abstract: When seismic and multi-beam bathymetric data from the northern shelf and slope of the C... more Abstract: When seismic and multi-beam bathymetric data from the northern shelf and slope of the Cinarcik Basin are interpreted, some sub-marine landslides are observed clearly. Additionally, seismic data indicate that upper surface of the submarine extension of the Paleozoic aged rocks has NNE-SSW oriented basin and ridge type morphology controlled by the secondary faults of the NAFZ. Basins are fulfilled by Plio-Quaternary sediments, which are cut by strike-slif faults on the shelf and slope. Thickness of these deposits increases up ...
Summary This study presents recent progress “Part-2” in research of Lake Ercek Seismic Survey (LE... more Summary This study presents recent progress “Part-2” in research of Lake Ercek Seismic Survey (LESS, 2015) Project to analyze earthquake faulting characteristics and source mechanisms of the selected aftershocks recorded at KOERI network (2011–2012) in the Lake Ercek Area (Eastern Anatolia) by using Centroid Moment Tensor (CMT) Inversion and Stress Tensor Analysis of P- and S-waves with a support of the high-resolution shallow seismic reflection data and field survey observations from Lake Ercek Basin.
Calisma, Canakkale Bogazi’nda derinligi 25.00-83.00 m arasi degisen; 2007 yaz aylarinda olmak uze... more Calisma, Canakkale Bogazi’nda derinligi 25.00-83.00 m arasi degisen; 2007 yaz aylarinda olmak uzere 12 ve gecmis yillarda ise 14 ayri noktadan alinmis olan 26 ornek uzerinde yurutulmustur. Orneklerden 8’i cok zengin denilebilecek foraminifer ve ostrakod toplulugunu icermektedir. Yalniz ikisi ise zengin bir mollusk faunasina sahiptir. Foraminifer toplulugu 73 cins ve 118 tur, ostrakod toplulugu ise 36 cins ve 41 tur ile temsil edilmektedir. Bunlara nazaran mollusk gurubundan pelesipodlar 13 cins ve 12 tur, gastropodlar 11 cins ve 16 ture sahiptir. Bu bilgilerin isiginda deginilen alanin Ege Denizi ve Akdeniz faunasi etkisinde kaldigi anlasilmaktadir. Orneklerden ucunun cok zengin bir bentik foraminifer ve ostrakod topluluguna sahip olmasi, birinde iri foraminifer kavkilarinin gozlenmesi ve bunlardan bazilarinda renklenme ile jips kristallerinin varligi, bu orneklerin alinmis oldug u alanlarda fay/faylara bagli karbonat, sulfat ve eser elementce zengin su cikislarinin varligi...
Abstract In this study, we analysed the source mechanisms and faulting pattern of the aftershocks... more Abstract In this study, we analysed the source mechanisms and faulting pattern of the aftershocks in the Lake Ercek area, Eastern Anatolia, during the 2011 Van event (Mw 7.1). The fault plane solutions of the aftershocks were used to derive a stress tensor acting around Lake Ercek. The estimated seismological parameters (focal mechanism solutions, stress tensor, and fault focal analyses) were integrated with field surveys and high resolution seismic reflection data so as to better understand the main faulting patterns and deformational features which are the causatives of the observed geomorphological features within and around Lake Ercek. The focal parameters of the 56 aftershocks with magnitude range 3.5 ≤ Mw ≤ 5.5 were obtained using the regional broadband seismic data from the network of Kandilli Observatory and Earthquake Research Institute (KOERI) through the Centroid Moment Tensor (CMT) inversion of locally observed broadband-waves. The implications for the lateral variation of the stress field in the lake area were based on information derived from integration of seismicity and stress tensor inversion results. The major outcomes of our analyses were as follows: (a) The maximum principal stress axis is close to horizontal and aligned in NNW-SSE direction, the minimum compressional stress axis is close to vertical and aligned in an ENE-WSW direction, the intermediate stress axis is close to horizontal and is parallel to the strike of the ruptured fault plane, while the stress ratio is (R = 0.6); (b) the lake basin is mostly deformed by dip-slip faults (dips ≥ 45–60°) in and along its margins where the various folds, basement highs with eroded surfaces and several low-angle normal faults are evident; (c) the majority of the aftershocks have reverse-thrust mechanism with some strike-slip components in the Lake Ercek area (N- and S-margins). Strike-slip and normal faulting events are also evident (E- and W-margins, respectively); (d) the normal and reverse mechanisms with some strike-slip component are mostly confined in the upper crust (0–15 km), compatible with NS-striking normal and WE-striking reverse faults in the marginal sections of the lake; (e) the WE-striking reverse faulting in the N- and S-margins seems to have the seismic potential to generate destructive earthquakes in the lake area; (f) the tectonic implications of the regional stress field and ongoing deformation processes in the lake are defined and supported by field observations and seismic reflection data. The result of these analyses reveals N-S compression/W-E extension in the lake and also the collisional/compressional regime taking place in a region of Lakes Van and Ercek.
Istanbul Bogazi, bir akarsu vadisinin tektonik olarak evrimlestigi dar bir kanaldir ve evrimi sir... more Istanbul Bogazi, bir akarsu vadisinin tektonik olarak evrimlestigi dar bir kanaldir ve evrimi sirasinda bogaz kanalinin icerisine kalin bir cokel istif depolanmistir. Ayrintili sismik ve batimetrik inceleme, gunumuz bogaz tabani sekillenmesinde uc onemli faktorun etkisini gosterir. Bu etkenler; deniz tabaninda yaygin bir asinim, agirlikli olarak sediman suruklenmeleri ve kitle hareketleri olarak izlenen birikim ve faylanma olarak gozlenmektedir. Deniz tabani sekillenmesini en etkin olarak denetleyen asinim etkisi kendisini, bogaz cokellerinin ust bolumunu olusturan paralel tabakali istifin yayginca erozyona ugramis olmasi ile gostermektedir. Soz konusu asinim yuzeyi, gunumuzde onemli olcude Istanbul Bogazi deniz tabanini olusturur. Asinmaya ugramis olan cokel miktari ise, yaklasik olarak 2x108 m3 olarak hesaplanmistir. Sismik veri uzerinde belirlenen asinim miktari ve deniz tabani morfolojisi, soz konusu asinmayi olusturan akintinin guneyden kuzeye dogru gelistigini gostermektedir. ...
ABSTRACT Although there are many research studies on the northern and southern branches of the No... more ABSTRACT Although there are many research studies on the northern and southern branches of the North Anatolian fault, cutting through the deep basins of the Sea of Marmara in the north and creating a series of pull-apart basins on the southern mainland, little data is available about the geometrical and kinematical characteristics of the middle strand of the North Anatolian fault. The first detailed geometry of the middle strand of the North Anatolian fault along the southern Marmara shelf, including the Gemlik and Bandırma Bay, will be given in this study, by a combined interpretation of different seismic data sets. The characteristic features of its segments and their importance on the paleogeographic evolution of the southern shelf sub-basins were defined. The longest one of these faults, the Armutlu-Bandırma segment, is a 75-km long dextral strike-slip fault which connects the W–E trending Gençali segment in the east and NE–SW trending Kapıdağ-Edincik segment in the west. In this context, the Gemlik Bay opened as a pull-apart basin under the control of the middle strand whilst a new fault segment developed during the late Pleistocene, cutting through the eastern rim of the bay. In this region, a delta front forming the paleoshoreline of the Gemlik paleolake was cut and shifted approximately 60 ± 5 m by the new segment. The same offset on this fault was also measured on a natural scarp of acoustic basement to the west and integrated with this paleoshoreline forming the slightly descending topset–foreset reflections of the delta front. Therefore the new segment is believed to be active at least for the last 30,000 years. The annual lateral slip rate representing this period of time will be 2 mm, which is quite consistent with modern GPS measurements. Towards the west, the Bandırma Bay is a rectangular transpressional basin whilst the Erdek Bay is a passive basin under the control of NW–SE trending faults. When the water level of the paleo-Marmara lake dropped down to −90 m, the water levels of the suspended paleolakes of Bandırma and Gemlik on the southern shelf were −50.3 (−3.3 Global Isostatic Adjustment—GIA) and −60.5 (−3.3 GIA) m below the present mean sea level, respectively. As of today a similar example can be seen between the Sea of Marmara and the shallow freshwater lakes of Manyas and Uluabat. Similarly, the paleolakes of Gemlik and Bandirma were affected by the water level fluctuations at different time periods, even though both lakes were isolated from the Sea of Marmara during the glacial periods.
ABSTRACT In general, potential field data are noisy due to the surveys in rugged topography. Stan... more ABSTRACT In general, potential field data are noisy due to the surveys in rugged topography. Standard reduction techniques are not fully adequate to eliminate this problem. Most of the interpretation techniques require the observations measured on the horizontal surface. Furthermore, upward and downward continuations, vertical derivatives can improve the ambiguity in the potential field data. In present, there are methods for the application of the analytical continuations and derivatives, but these are not successful enough due to technical restrictions and unwanted edge effects. In this paper, an easy and efficient technique known as the equivalent source is applied to the observations made over the rugged topography. Presented method is tested on synthetic example using an anomaly of a sphere located below the synthetic topography. At first, our method is applied only to obtain topographic distortion corrected map by moving forward windowed parts of the area. Afterwards, analytic continuations of the topographic distortion corrected map are obtained. Finally, vertical derivative map is obtained from the analytic continuations of the topographic distortions corrected map. Amplitudes are controlled along profiles on top of theoretical and calculated spheres. A good correlation can be observed from the amplitude values. This method is also applied to the field data. The second vertical derivative map is produced from the topographic distortion corrected and 5 km upward continued gravity map of the region. We note that by the interpretations identified faults in these map are in good agreement with the faults shown in the structural map of the region.
Επιστημονική Επετηρίδα του Τμήματος Γεωλογίας (Α. Π. Θ.), 2010
Abstract: When seismic and multi-beam bathymetric data from the northern shelf and slope of the C... more Abstract: When seismic and multi-beam bathymetric data from the northern shelf and slope of the Cinarcik Basin are interpreted, some sub-marine landslides are observed clearly. Additionally, seismic data indicate that upper surface of the submarine extension of the Paleozoic aged rocks has NNE-SSW oriented basin and ridge type morphology controlled by the secondary faults of the NAFZ. Basins are fulfilled by Plio-Quaternary sediments, which are cut by strike-slif faults on the shelf and slope. Thickness of these deposits increases up ...
Summary This study presents recent progress “Part-2” in research of Lake Ercek Seismic Survey (LE... more Summary This study presents recent progress “Part-2” in research of Lake Ercek Seismic Survey (LESS, 2015) Project to analyze earthquake faulting characteristics and source mechanisms of the selected aftershocks recorded at KOERI network (2011–2012) in the Lake Ercek Area (Eastern Anatolia) by using Centroid Moment Tensor (CMT) Inversion and Stress Tensor Analysis of P- and S-waves with a support of the high-resolution shallow seismic reflection data and field survey observations from Lake Ercek Basin.
Calisma, Canakkale Bogazi’nda derinligi 25.00-83.00 m arasi degisen; 2007 yaz aylarinda olmak uze... more Calisma, Canakkale Bogazi’nda derinligi 25.00-83.00 m arasi degisen; 2007 yaz aylarinda olmak uzere 12 ve gecmis yillarda ise 14 ayri noktadan alinmis olan 26 ornek uzerinde yurutulmustur. Orneklerden 8’i cok zengin denilebilecek foraminifer ve ostrakod toplulugunu icermektedir. Yalniz ikisi ise zengin bir mollusk faunasina sahiptir. Foraminifer toplulugu 73 cins ve 118 tur, ostrakod toplulugu ise 36 cins ve 41 tur ile temsil edilmektedir. Bunlara nazaran mollusk gurubundan pelesipodlar 13 cins ve 12 tur, gastropodlar 11 cins ve 16 ture sahiptir. Bu bilgilerin isiginda deginilen alanin Ege Denizi ve Akdeniz faunasi etkisinde kaldigi anlasilmaktadir. Orneklerden ucunun cok zengin bir bentik foraminifer ve ostrakod topluluguna sahip olmasi, birinde iri foraminifer kavkilarinin gozlenmesi ve bunlardan bazilarinda renklenme ile jips kristallerinin varligi, bu orneklerin alinmis oldug u alanlarda fay/faylara bagli karbonat, sulfat ve eser elementce zengin su cikislarinin varligi...
Abstract In this study, we analysed the source mechanisms and faulting pattern of the aftershocks... more Abstract In this study, we analysed the source mechanisms and faulting pattern of the aftershocks in the Lake Ercek area, Eastern Anatolia, during the 2011 Van event (Mw 7.1). The fault plane solutions of the aftershocks were used to derive a stress tensor acting around Lake Ercek. The estimated seismological parameters (focal mechanism solutions, stress tensor, and fault focal analyses) were integrated with field surveys and high resolution seismic reflection data so as to better understand the main faulting patterns and deformational features which are the causatives of the observed geomorphological features within and around Lake Ercek. The focal parameters of the 56 aftershocks with magnitude range 3.5 ≤ Mw ≤ 5.5 were obtained using the regional broadband seismic data from the network of Kandilli Observatory and Earthquake Research Institute (KOERI) through the Centroid Moment Tensor (CMT) inversion of locally observed broadband-waves. The implications for the lateral variation of the stress field in the lake area were based on information derived from integration of seismicity and stress tensor inversion results. The major outcomes of our analyses were as follows: (a) The maximum principal stress axis is close to horizontal and aligned in NNW-SSE direction, the minimum compressional stress axis is close to vertical and aligned in an ENE-WSW direction, the intermediate stress axis is close to horizontal and is parallel to the strike of the ruptured fault plane, while the stress ratio is (R = 0.6); (b) the lake basin is mostly deformed by dip-slip faults (dips ≥ 45–60°) in and along its margins where the various folds, basement highs with eroded surfaces and several low-angle normal faults are evident; (c) the majority of the aftershocks have reverse-thrust mechanism with some strike-slip components in the Lake Ercek area (N- and S-margins). Strike-slip and normal faulting events are also evident (E- and W-margins, respectively); (d) the normal and reverse mechanisms with some strike-slip component are mostly confined in the upper crust (0–15 km), compatible with NS-striking normal and WE-striking reverse faults in the marginal sections of the lake; (e) the WE-striking reverse faulting in the N- and S-margins seems to have the seismic potential to generate destructive earthquakes in the lake area; (f) the tectonic implications of the regional stress field and ongoing deformation processes in the lake are defined and supported by field observations and seismic reflection data. The result of these analyses reveals N-S compression/W-E extension in the lake and also the collisional/compressional regime taking place in a region of Lakes Van and Ercek.
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