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Öğe 24 January 2020 Sivrice (Elazig) earthquake damages and determination of earthquake parameters in the region(Techno-Press, 2020) Isik, Ercan; Aydin, Mehmet Cihan; Buyuksarac, AydinThe 24 January 2020 (Mw=6.8) earthquake with epicentre in Elazig (Sivrice) on the East Anatolian Fault Zone caused loss of life and property. The information was given about the seismotectonic setting and regional seismicity along this fault zone and aftershock activity and ground motion data of this earthquake. Earthquake parameters were obtained for five different earthquake stations which were closer to the epicentre. Horizontal and vertical design spectra were obtained for the geographic locations for each earthquake station. The obtained spectra for the earthquake epicentre were compared with selected appropriate attenuation relationships. The damages after earthquake were evaluated via geotechnical and structural aspects. This study also aims to investigate the cause-effect relationships between structural damage in reinforced-concrete and masonry structures, respectively. The lack of engineering services was effective on the amount of damage in masonry structures. Insufficient reinforcement and concrete strength, dimensions and inadequate detailing increased the amount of damage in reinforced-concrete structures. Importance should be given to negative parameters that may weaken the defence mechanisms of structures for earthquake-resistant structural design.Öğe 3D MODELLING AND STRUCTURAL INVESTIGATION OF THE CENTRAL VOLCANICS IN SLOVAKIA USING MAGNETIC DATA(Carpathian Assoc Environment And Earth Sciences, 2013) Bektas, Ozcan; Buyuksarac, Aydin; Rozimant, KamilThe Central volcanics, located in central part of Slovakia, is characterized by intense andesitic volcanic activity that resulted in the formation of stratavolcanoes and dome complexes of Middle and Late Miocene age. The basement area has been affected tectonically resulting in the formation of horst and graben structures. The Central Slovakian Volcanic Field (CSVF) exhibits a very complex magnetic anomaly. A 3-km upward continued magnetic map indicates a deep-seated source for this magmatism. The pseudogravity transformation of the upward continued anomaly has also been constructed. This anomaly was modelled by a 3D-method. The anomalous body lies between the depths of 4.4 to 8.5 km beneath the surface of the CSVF. Volcanic structures and some lineaments are presented on the maxima of the horizontal gradient of the pseudogravity anomaly map. They are well correlated with the structural map of CSVF.Öğe A Comparative Evaluation of Earthquake Code Change on Seismic Parameter and Structural Analysis; A case of Turkey(Springer Heidelberg, 2022) Buyuksarac, Aydin; Isik, Ercan; Bektas, OzcanTurkey, which is one of the countries with high seismic risk, has made significant changes in both seismic risk maps and seismic design codes over time by adapting to these developments. Information about the important changes in the last two earthquake maps and provisions in Turkey was given and the effects of these changes on structural and seismic parameters were examined in this study. In order to make comparisons of seismic parameters, seven different settlements from seven different geographical regions in Turkey were taken into account which have the same seismic risk in the previous earthquake risk map. Seismic moments were also calculated separately for these locations to describe the intensity of future tectonic activity. With the current earthquake hazard map, geographical location-specific earthquake risk has been started to be used instead of regional risk. For the selected settlements with the same seismic risk in the previous map, the seismic risks were found high in some and low in some with the current hazard map. In addition, structural analyses were carried out for the sample reinforced-concrete building with the same structural characteristics in these seven different settlements in order to reveal the effect of the code and map change on the structural analysis. While the target displacements expected from the structures for the settlements with the same seismic risk take the same values, the target displacements are obtained differently for each, since the specific design spectrum is used for each location with the current map.Öğe A Comparative Study of the Effects of Earthquakes in Different Countries on Target Displacement in Mid-Rise Regular RC Structures(Mdpi, 2022) Isik, Ercan; Hadzima-Nyarko, Marijana; Bilgin, Huseyin; Ademovic, Naida; Buyuksarac, Aydin; Harirchian, Ehsan; Bulajic, BorkoData from past earthquakes is an important tool to reveal the impact of future earthquakes on engineering structures, especially in earthquake-prone regions. These data are important indicators for revealing the seismic loading effects that structures will be exposed to in future earthquakes. Five different earthquakes from six countries with high seismic risk were selected and were within the scope of this study. The measured peak ground acceleration (PGA) for each earthquake was compared with the suggested PGA for the respective region. Structural analyzes were performed for a reinforced-concrete (RC) building model with four different variables, including the number of storeys, local soil types, building importance class and concrete class. Target displacements specified in the Eurocode-8 were obtained for both the suggested and measured PGA values for each earthquake. The main goal of this study is to reveal whether the proposed and measured PGA values are adequately represented in different countries. We tried to reveal whether the seismic risk was taken into account at a sufficient level. In addition, target displacements have been obtained separately in order to demonstrate whether the measured and suggested PGA values for these countries are adequately represented in structural analysis and evaluations. It was concluded that both seismic risk and target displacements were adequately represented for some earthquakes, while not adequately represented for others. Comments were made about the existing building stock of the countries considering the obtained results.Öğe Analysis of local site conditions through geophysical parameters at a city under earthquake threat: Canakkale, NW Turkey(Elsevier Science Bv, 2019) Bekler, Tolga; Demirci, Alper; Ekinci, Yunus Levent; Buyuksarac, AydinCanakkale is the second province, after Istanbul, that has territories in both Asia and Europe. The city, also known as Dardanelles, is located on the Gallipoli peninsula in the northwest of Turkey, and the Biga peninsula which is an extension of Anatolia at the west. The region is tectonically quite active and it has high earthquake generation potential. The city has experienced a significant earthquake (Mw = 6.8) once again that occurred on May 24, 2014. In addition to these challenges, remarkable part of the city's territory and also potential new settlement areas are located on thick alluvium. Thus, mentioned-above disadvantages clearly increase the importance of this study, which focuses on determining the areas having different earthquake hazard potentials with regard to local site conditions by performing seismic risk assessments, as well as providing a basis for the preparation of settlement suitability maps on different scales that will lead knowledge for zoning plans. To that end, an integrated geophysical and geotechnical study was performed in a detailed manner. Multi-channel analysis of surface waves (MASW) and microtremor (MT) measurements were carried out at properly distributed 110 stations representing the whole survey area. The geotechnical study, planned to contribute geophysical interpretation, involved the drilling of 110 boreholes that are close to geophysical measurement stations. In addition to examining Vs30 variations based on the MASW, the ground dominant vibration period maps were also produced through MT time series analysis. In particular, the mean Vs velocity (Vs30) up to the first 30 m and the ground oscillation period change based on spectral amplitude ratios (HVSR) yielded substantial information that helped generate the seismic microzonation maps and also make the ground classification. These outputs contributed to exhibit the risk zones in the coastal city that has a dense and narrow settlement plan. (C) 2019 Elsevier B.V. All rights reserved.Öğe Assessment of potential seismic hazard and site effect in Antakya (Hatay Province), SE Turkey(Springer, 2011) Over, Semir; Buyuksarac, Aydin; Bekta, Ozcan; Filazi, AhmetAntakya city is at risk because of strong earthquakes occurring in the area, and different soil conditions that can produce variation of the ground motion amplification. Microzonation of cities provides a basis for site-specific hazard analysis in urban settlements. In particular, seismic microzonation can be provided by means of detailed seismic assessment of the area, including earthquake recordings and geological studies. In this paper, we propose a preliminary microzonation map for the city of Antakya, based on the variation of the dominant periods and shear velocities of the sediments covering the area. The periods are retrieved from microtremor measurements conducted at 69 sites, using the horizontal-to-vertical spectral ratio technique. The results of microtremor analysis were compared with data obtained from refraction microtremor (ReMi) measurements at four profiles crossing the studied area. According to the classification of dominant periods, Antakya city can be divided into five zones, probably prone to different levels of seismic hazard. The shorter natural periods are in inner Antakya and both the sides of Asi River (i.e., northern and southern parts). The eastern and western parts of Antakya have maximum dominant periods. The V (s) (30) values were calculated by using the ReMi method along the profiles. Antakya city has V (s) (30) values in the range of category C of the national earthquake hazard reduction programme site classification.Öğe Comment to Comparative petroleum systems analysis of the interior basins of Turkey: Implications for petroleum potential [Mar. Pet. Geol. 26 (2009) 1656-1676](Elsevier Sci Ltd, 2010) Buyuksarac, Aydin; Erik, Nazan Yalcin[Anstract Not Available]Öğe Crustal Structure of Turkey from Aeromagnetic, Gravity and Deep Seismic Reflection Data(Springer, 2012) Ates, Abdullah; Bilim, Funda; Buyuksarac, Aydin; Aydemir, Attila; Bektas, Ozcan; Aslan, YaseminIn this paper, aeromagnetic and gravity anomalies obtained from the General Directorate of Mineral Research and Exploration were subjected to upward continuation to 3 km from the ground surface to suppress shallow effects and to expose only regional, deep sources. Then, a reduction to pole (RTP) map of aeromagnetic anomalies was produced from the 3 km upward continued data. A sinuous boundary to the south of Turkey is observed in the RTP map that may indicate the suture zone between the Anatolides and African/Arabian Plates in the closure time of the Tethys Ocean. The sinuous boundary can be correlated with the recent palaeo-tectonic maps. The southern part of the sinuous boundary is quite different and less magnetic in comparison with the northern block. In addition, maxspots maps of the aeromagnetic and gravity anomalies were produced to find out and enhance the boundaries of tectonic units. Crustal thickness, recently calculated and mapped for the western Turkey, is also extended to the whole of Turkey, and the crustal thicknesses are correlated with the previous seismological findings and deep seismic sections. The average crustal thickness calculations using the gravity data are about 28 km along the coastal regions and increase up to 42 km through the Iranian border in the east of Turkey. Density and susceptibility values used as parameters for construction of two-dimensional (2D) gravity and magnetic models were compiled in a table from different localities of Turkey. 2D models indicate that all of the anomalous masses are located in the upper crust, and this could be well correlated with the earthquakes which occurred at shallow depths.Öğe Evaluation of Gravity and Aeromagnetic Anomalies for the Deep Structure and Possibility of Hydrocarbon Potential of the Region Surrounding Lake Van, Eastern Anatolia, Turkey(Springer, 2014) Aydemir, Attila; Ates, Abdullah; Bilim, Funda; Buyuksarac, Aydin; Bektas, OzcanThe North Anatolian Fault (NAF) is not observed on the surface beyond 40 km southeast of Karliova town toward the western shoreline of Lake Van. Various amplitudes of gravity and aeromagnetic anomalies are observed around the lake and surrounding region. In the gravity anomaly map, contour intensity is observed from the north of Mus city center toward Lake Van. There is a possibility that the NAF extends from here to the lake. Because there is no gravity data within the lake, the extension of the NAF is unknown and uncertain in the lake and to the east. Meanwhile, it is observed from the aeromagnetic anomalies that there are several positive and negative amplitude anomalies aligned around a slightly curved line in the east-west direction. The same curvature becomes much clearer in the analytic signal transformation map. The volcanic mountains of Nemrut and Suphan, and magnetic anomalies to the east of the Lake Van are all lined up and extended with this slightly curved line, provoking thoughts that a fault zone that was not previously mapped may exist. The epicenter of the major earthquake event that occurred on October 23, 2011 is located on this fault zone. The fault plane solution of this earthquake indicates a thrust fault in the east-west direction, consistent with the results of this study. Volcanic mountains in this zone are accepted as still being active because of gas seepages from their calderas, and magnetic anomalies are caused by buried causative bodies, probably magmatic intrusions. Because of its magmatic nature, this zone could be a good prospect for geothermal energy exploration. In this study, the basement of the Van Basin was also modelled three-dimensionally (3D) in order to investigate its hydrocarbon potential, because the first oil production in Anatolia was recorded around the Kurzot village in this basin. According to the 3D modelling results, the basin is composed of three different depressions aligned in the N-S direction and many prospective structures were observed between and around these depressions where the depocenter depths may reach down to 10 km.Öğe Geophysical investigation and hydrocarbon potential of Cankiri-Corum Basin, Turkey(Elsevier Science Bv, 2013) Aslan, Yasemin; Buyuksarac, Aydin; Erik, Nazan Yalcin; Aydemir, Attila; Ates, AbdullahThe Cankiri-Corum Basin is one of the larger, onshore sedimentary basins in central Turkey. In this paper, the integration of geophysical data and geological findings in the Cankiri-Corum Basin was performed and they both present a complex basin structure. In the frame of geophysical study, two-dimensional (20) models were constructed using gravity and magnetic anomalies. Seismic sections were interpreted and correlated with the 2D models using the borehole data as control. Basement depth, basin geometry and sources for magnetic anomalies along the 20 model profiles were determined in integration of seismic, gravity, aeromagnetic and borehole data. Seismic section CC-L-1 is correlated with the Topuzsaray-1 well. Tuffs and volcanic units penetrated in this well might be correlated across a reverse fault close to the borehole. Seismic sections, CC-L-2 and CC-L-3, are consistent with the gravity models at the deeper parts of the sections. On the other hand, there are inconsistencies in the shallow sections with the gravity models due to unexpected velocity variations in both the horizontal and vertical directions. The average depth of basement was found to be about 5 km by means of gravity modelling, which was correlated with the seismic sections. Magnetic anomalies are represented by intense values in the NW portion of the study area, but they indicate very low intensities in the middle of the map. A reverse magnetised body to the north of the study area was modelled in 2D along a profile and it was interpreted that this body might be an ophiolitic remnant. Polarities of many anomalies to the south and northeast of the region indicate remanent magnetisation. Alignment of the polarities extends in the northwest direction, indicating that the region rotated in the anticlockwise direction. Because there is around a 5 km sedimentary basin fill in the study area, it may exhibit hydrocarbon potential and the Yesilcat oil seep evidences this potential. Surface samples were collected to examine source rock potential and to correlate with the Yesilcat seep by analysing the organic geochemical properties. In this study, 72 samples were collected from different formations and it was found that the Yoncali Formation displays better source rock potential than the other formations studied. (C) 2013 Elsevier B.V. All rights reserved.Öğe Geophysical Investigation of Mount Nemrut Stratovolcano (Bitlis, Eastern Turkey) Through Aeromagnetic Anomaly Analyses(Springer Basel Ag, 2020) Ekinci, Yunus Levent; Buyuksarac, Aydin; Bektas, Ozcan; Ertekin, CanQuaternary Mount Nemrut stratovolcano, having a spectacular summit caldera and associated lakes, is located north of the Bitlis-Zagros suture zone, Eastern Turkey. Although much attention has been paid to its geology, morphology, history and biology, a detailed geophysical investigation has not been performed in this special region. Thus, we attempted to characterize the stratovolcano and the surroundings using total field aeromagnetic anomalies. Potential field data processing techniques helped us to interpret geologic sources causing magnetic signatures. Resulting image maps obtained from some linear transformations and a derivative-based technique revealed general compatibility between the aeromagnetic anomalies and the near-surface geology of the study area. Some high amplitude magnetic anomalies observed north of the Nemrut caldera rim are associated with the latest bimodal volcanic activity marked by lava fountains and comenditic-basaltic flows occurred along the rift zone. After minimizing the high-frequency effects, a pseudogravity-based three-dimensional inversion scheme revealed that the shallowest deep-seated sources are located about 3.0 km below the ground surface. Two-dimensional normalized full gradient solutions also exposed the depths of these anomaly sources, in good agreement with the inversion results. This first geophysical study performed through aeromagnetic anomalies clearly gave insights into some main magnetized structures of the Mount Nemrut stratovolcano.Öğe Geophysical investigations at Agadere Cemetery, Gallipoli Peninsular, NW Turkey(Taylor & Francis Ltd, 2014) Buyuksarac, Aydin; Yalciner, Cahit Caglar; Ekinci, Yunus Levent; Demirci, Alper; Yucel, Mehmet AliHistorical cemeteries are challenging targets for geophysical prospection but some non-destructive imaging techniques may be successful for mapping buried cemeteries if applied appropriately. Ground-Penetrating-Radar (GPR) has generally been considered to be the only geophysical method for determining cemeteries; however, Electrical-Resistivity-Tomography (ERT) and Magnetic-Imaging (MI), may determine geophysical traces of such cemeteries. Thus, as a first attempt at applying geophysical methods in the cemetery area of the Gallipoli Peninsula, these techniques were used to explore the buried graves at Agadere Cemetery. In this study, measured apparent resistivity data were processed using a two-dimensional (2D) tomographic inversion scheme. Resultant resistivity depth slices and volumetric resistivity images clearly showed the anomaly zone, which may be attributed to anthropogenic burials. Additionally, three-dimensional (3D) visualization of GPR results indicated some anomalies, much like the resistivity anomalies in terms of location. MI data were processed using linear transformations and an analytic signal image map presented anomaly zones located in some parts of the area, which are in agreement with those obtained by ERT and GPR surveys. Results derived from data processing techniques showed that these methods are suitable for bordering the locations of other buried historical graves in areas that have the same geological environment in the Peninsula.Öğe Geophysical Variations During the Total Solar Eclipse in 2006 in Turkey(Tubitak Scientific & Technological Research Council Turkey, 2011) Ates, Abdullah; Buyuksarac, Aydin; Bektas, OzcanIt has been observed that some geophysical parameters could be changed during a solar eclipse. We have therefore measured gravity and magnetic fields during solar eclipses. We also measured the gravity field during the previous eclipse on the 11(th) of August, 1999. Gravity measurements on the 29(th) of March, 2006 are compared with previous gravity measurements at the same location during the eclipse on the 11(th) of August, 1999. Both showed the same behaviour during the eclipses. Gravity measurements showed fluctuations during both eclipses. A decrease in the intensity of the magnetic field was observed. Low-pass filtered magnetic data show peculiarity during the eclipse which can be correlated with the fluctuations in the gravity fields.Öğe Indoor and outdoor Radon concentration measurements in Sivas, Turkey, in comparison with geological setting(Elsevier Sci Ltd, 2010) Mihci, Metin; Buyuksarac, Aydin; Aydemir, Attila; Celebi, NilgunIndoor and soil gas Radon (Rn-222) concentration measurements were accomplished in two stages in Sivas, a central eastern city in Turkey. In the first stage, CR-39 passive nuclear track detectors supplied by the Turkish Atomic Energy Authority (TAEA) were placed in the selected houses throughout Sivas centrum in two seasons; summer and winter. Before the setup of detectors, a detailed questionnaire form was distributed to the inhabitants of selected houses to investigate construction parameters and properties of the houses, and living conditions of inhabitants. Detectors were collected back two months later and analysed at TAEA laboratories to obtain indoor Rn-222 gas concentration values. In the second stage, soil gas Rn-222 measurements were performed using an alphameter near the selected houses for the indoor measurements. Although Rn-222 concentrations in Sivas were quite low in relation with the allowable limits, they are higher than the average of Turkey. Indoor and soil gas Rn-222 concentration distribution maps were prepared seperately and these maps were applied onto the surface geological map. In this way, both surveys were correlated with the each other and they were interpreted in comparison with the answers of questionnaire and the geological setting of the Sivas centrum and the vicinity. (C) 2010 Elsevier Ltd. All rights reserved.Öğe Non-destructive damage analysis in Kariye (Chora) Museum as a cultural heritage building(Elsevier, 2019) Yalciner, C. Caglar; Buyuksarac, Aydin; Kurban, Yunus CanNon-destructive testing methods are being increasingly used in the evaluation of cultural heritage buildings. Combined geophysical methods especially can be applied to structural evaluations of these kinds of buildings. Ultrasonic Pulse Velocity (UPV) Test and Ground Penetrating Radar (GPR) were used in a complementary way as non-destructive testing techniques in this study. The main aim of the study is to analyze the internal structural configuration as well as the quality of the stone, internal geometry and physical properties of some structural elements. It was determined that the main cracks in all walls within the building are on an axis. The cracks on this crack axis were determined to have been filled during previous repairs on the GPR profiles. However, the filling material is different from the building materials that constitute the building walls and at the same time the presence of void spaces was determined. (C) 2019 Elsevier B.V. All rights reserved.Öğe Preliminary seismic microzonation of Sivas city (Turkey) using microtremor and refraction microtremor (ReMi) measurements(Springer, 2013) Buyuksarac, Aydin; Bektas, Ozcan; Yilmaz, Huseyin; Arisoy, M. OzguSivas city, located in the inner east part of Anatolia (Turkey), is far from seismic sources. However, the city is under risk owing to strong earthquakes occurring around the area, and different soil conditions that can produce variation in the ground motion amplification. Microzonation of cities provides a basis for site-specific hazard analysis in urban settlements. In particular, seismic microzonation can be achieved by means of detailed seismic assessment of the area, including earthquake recordings and geological studies. In this paper, we propose a preliminary microzonation map for the city of Sivas, based on the variation in the dominant periods of the sediments covering the area. The periods are retrieved from microtremor measurements conducted at 114 sites, using the horizontal-to-vertical spectral ratio technique. The results of microtremor analysis were compared with those obtained from refraction microtremor measurements at two profiles crossing the studied area. According to the classification of dominant periods, Sivas area can be divided into four zones, probably prone to different levels of seismic hazard. However, specific studies including analysis of weak earthquakes are required in the future to validate our microzonation map.Öğe The Effect of Site-Specific Design Spectrum on Earthquake-Building Parameters: A Case Study from the Marmara Region (NW Turkey)(Mdpi, 2020) Isik, Ercan; Buyuksarac, Aydin; Ekinci, Yunus Levent; Aydin, Mehmet Cihan; Harirchian, EhsanThe Marmara Region (NW Turkey) has experienced significant earthquakes (M > 7.0) to date. A destructive earthquake is also expected in the region. To determine the effect of the specific design spectrum, eleven provinces located in the region were chosen according to the Turkey Earthquake Building Code updated in 2019. Additionally, the differences between the previous and updated regulations of the country were investigated. Peak Ground Acceleration (PGA) and Peak Ground Velocity (PGV) were obtained for each province by using earthquake ground motion levels with 2%, 10%, 50%, and 68% probability of exceedance in 50-year periods. The PGA values in the region range from 0.16 to 0.7 g for earthquakes with a return period of 475 years. For each province, a sample of a reinforced-concrete building having two different numbers of stories with the same ground and structural characteristics was chosen. Static adaptive pushover analyses were performed for the sample reinforced-concrete building using each province's design spectrum. The variations in the earthquake and structural parameters were investigated according to different geographical locations. It was determined that the site-specific design spectrum significantly influences target displacements for performance-based assessments of buildings due to seismicity characteristics of the studied geographic location.Öğe The Relationship Between Concrete Strengths Obtained by Destructive and Non-destructive Methods(Springer Int Publ Ag, 2020) Karahan, Sebnem; Buyuksarac, Aydin; Isik, ErcanQuality of material is an important parameter in structural design. Quality of concrete as a widely used material may be controlled by using pressure testing devices. For this purpose, standard methods are used. However, these methods are difficult, time-consuming and costly. Hence, using non-destructive methods, which are also faster and less costly, has become a must. In this study, ultrasonic pulse velocity and surface hardness values are obtained from samples prepared in the laboratory environment in the context of non-destructive methods and samples collected from an existing concrete structure. Destructive pressure testing is then used to find the compressive strength values of these samples. The study compares and contrasts results from non-destructive and destructive methods. Correlations with discrete and compound methods are obtained with non-destructive methods, and quality evaluation of these correlations is completed.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.
