Sürdürülebilir Kalkınma Amaçları
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- MakaleYalnız künye2015Tectonic evolution of the northern shelf of the Marmara Sea (Turkey): interpretation of seismic and bathymetric data
Tur, Huseyin; Hoskan, Nihan; Aktas, Gulten
This study is based on the geological interpretation of 250 km2 of multibeam bathymetric data coupled with 300 km of seismic profiles recorded on the northern shelf of the Marmara Sea offshore Büyükçekmece and Küçükçekmece Lagoons. The sea bottom morphology has a highly chaotic structure at the exit of the Büyükçekmece and Küçükçekmece lagoons. This chaotic surface structure is controlled by a basin-ridge system lying in the NE–SW direction at the exit of the Büyükçekmece Lagoon and by a relatively deep entrance observed at the exit of the Küçükçekmece Lagoon. In addition, the linear submarine slope parallel to the shoreline between the Istanbul Strait and the Küçükçekmece Lagoon is an important morphological structure of this area. The Istanbul Strait’s canyon on the northern shelf of the Marmara Sea and the elevated submarine plain west of this canyon are other important morphological structures observed at the sea bottom. The geologic interpretation of seismic profiles has allowed us to distinguish two seismo-stratigraphic units. The lower one is separated from the overlying units by a seismic sequence having a seismic facies from chaotic to parallel and the top represented by a high amplitude seismic reflector. Since these units get close to the sea bottom rising landwards, they are inferred to be the seaward continuation of the Oligocene–Upper Miocene units widely exposed on land. The upper unit, overlying the acoustic basement, whose parallel internal reflections onlap and downlap on the top of the acoustic basement, is interpreted as a Quaternary basin fill. Two groups of faults have been identified on seismic profiles and identified based on their characteristics in the study area. The first group consists of dip-slip faults trending NNE–SSW. These faults border the western slope of the Bosporus and the NNE–SSW trending basins offshore of the Büyükçekmece Lagoon. The second group of faults consists of NW–SE oriented strike-slip faults. These faults have created the linearities in the same direction at the sea bottom. As the result of comparison of these NW–SE-faults to the North Anatolian Fault Zone (NAFZ), this group of faults is likely to have a relation with the NAFZ. Therefore, it is considered that the mentioned faults may be reactivated in the region due to the stress created by the NAFZ.
- MakaleYalnız künye2015Biogeochemical characteristics of Rosa canina grown in hydrothermally contaminated soils of the Gümüşhane Province, Northeast Turkey
Vural, Alaaddin
Kırkpavli alteration area (Gümüşhane, Northeast Turkey) is contaminated by heavy metals such as Cd, Pb, As, Cu and Zn. The quantity of accumulation of heavy metal trace elements and macroelements in 32 leaves of Rosa canina of the Kırkpavli alteration area has been studied within the scope of geochemical studies. Element contents of samples were assessed using various parameters including descriptive statistics, factor analysis, correlation coefficients and bioaccumulation factor. Concentrations were detected in the acceptable range for Mo, Cu, Pb, Ni, As, Cd, Sb, P, Ti, Na, Se and Sn. Concentrations of Co, Mn, Ba and Hg were detected close to the acceptable values, whereas Zn, Fe, Sr, V, Ca, Cr, Mg, B, Al, K, W, Sc, Cs and Rb concentrations were detected above the acceptable values. Principal component analysis was used to identify the elements that have a close relationship with each other and/or similar origins. It has been concluded that Zn, Cu, As and Mo content of the plant were related to hydrothermal alteration process and they behaved together, whereas Mn and Fe were especially products of weathering conditions, also behaved together. In terms of macroelements, Ca, Mg and Na had similar behaviour, while P and K had the same correlation.
- Derleme MakaleYalnız künye2015Seismic b-Values, Bouguer Gravity and Heat Flow Data Beneath Eastern Anatolia, Turkey: Tectonic Implications
Maden, Nafiz; Öztürk, Serkan
In this paper, we analyze the relationships between the seismic b-values, Bouguer gravity and heat flow data in the Eastern Anatolia region of Turkey. For this purpose, spatial distributions of b-value, Bouguer gravity and heat flow have been presented for different depths and locations. In distinction to previous studies which have used only two parameters (gravity and seismic b-value or heat flow and seismic b-value), we have combined seismic b-values, Bouguer gravity and heat flow data to determine the new results on the active tectonics of the Eastern Anatolia region. Our analysis shows that there are significant and robust correlations amidst the heat flow data, Bouguer gravity anomaly and seismic b-values. The crustal structure is thick in areas where the large negative gravity anomalies and low b-values are observed. On the contrary, the regions with positive gravity anomalies and high b-values are likely to be associated with magma chambers or crustal low-velocity zones. We also provide some evidence suggesting that high b-values and high heat flow values can be related to the magmatic activities beneath the volcanic chain in the Eastern Pontide orogenic belt. Consequently, we have reached some conclusions for the Eastern Anatolia region: (1) The Moho to surface is rather thick and earthquakes are relatively smaller beneath the volcanic chain where the high heat flow values are observed, (2) a southward subduction model could have existed for the development of the Pontides during the late Mesozoic–Cenozoic era, (3) hot and unstable mantle lid zones or a lithosphere deprived of mantle under the study region is much more plausible, (4) a southward movement of the subduction plate and a northward extension of the Black Sea increase the state of stress along the trench axis and decrease the b-value, and (5) these movements may load the stress energy to the fault zones, thereby causing the catastrophic earthquakes in the Eastern Anatolia region.
- MakaleYalnız künye2014Assessment of liquefaction potential of Erzincan Province and its vicinity, Turkey
Subası Duman, E.; Ikizler, S.B.
One of the most important causes of damages after the earthquakes is the soil liquefaction. Liquefaction can be defined as temporary loss in strength of saturated sandy and silty deposits under transient and cyclic loadings due to excess pore water pressure. This study includes determination of liquefaction potential in Erzincan city center and its vicinity. Due to the proximity of the North Anatolian Fault Zone, in a probable earthquake, Erzincan Province is thought to be affected. In this context, the earthquake scenarios were produced using the empirical expressions. Liquefaction potential for different earthquake magnitudes was determined. These earthquake magnitudes were selected as 6.0, 6.5, 7.0, 7.5, respectively. Liquefaction potential was investigated using standard penetration test (SPT) data. The first stage of the study, 63 boreholes in different locations was drilled and SPT was performed. Disturbed and undisturbed soil samples were taken from these boreholes. Laboratory testing was performed to determine physical properties of soil samples, and liquefaction potential analyses were examined using three methods, namely Seed and Idriss (J Soil Mech Found Div ASCE 97(9):1249-1273, 1971), Tokimatsu and Yoshimi (Soil Found 23(4):56-74, 1983), Iwasaki et al. (Soil liquefaction potential evaluation with use of the simplified procedure. International Conference on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics, St. Louis, pp 209-214, 1981). In order to complete liquefaction analysis within a short time, MATLAB program was prepared. Liquefaction potential analyses were carried out with the MATLAB program. At the final stage of this study, liquefaction potential maps were prepared for different earthquake magnitudes. The expected results will be shared with the local authorities and important engineering remedial measurements will be proposed to prevent further life losses and to mitigate property losses.
- MakaleYalnız künye2014Pushover and nonlinear time history analysis evaluation of a RC building collapsed during the Van (Turkey) earthquake on October 23, 2011
Çavdar, Özlem; Bayraktar, Alemdar
The nonlinear seismic behavior of a collapsed reinforced concrete (RC) residential building in the city of Van in Turkey is investigated by the static pushover and nonlinear time history analyses. The selected RC structure was designed according to the 1975 version of Turkish Earthquake Code (TEC-1975). The building had experienced heavy damage, and it was demolished in the Van earthquake on October 23, 2011. The 2007 version of Turkish Earthquake Code (TEC-2007) is considered for the assessing seismic performance evaluation of the selected RC building. The RC structure presents collapse performance level under the earthquake loads. Besides, the analytical solutions show that different performance levels for the sections are obtained from the pushover and nonlinear time history methods.
- MakaleYalnız künye2012Virtual point detector for HPGe detectors for 26.6-1332 keV photon energies by experiment and Monte Carlo simulation
Çelik, N.; Çevik, U.; Küçükömeroğlu, B.
Variation of virtual point detector (VPD) position inside HPGe detector as a function of source photon energy for the energy range from 26.6 to 1,332 keV was investigated. Although VPD concept was well established for HPGe detectors from 59.5 to 10 MeV, a new attempt was made to obtain VPD positions for photon energies below 59.5 keV. It was found that VPD position shows different functional behavior for the energy ranges 26.6-59.5 keV and 59.5-1,332 keV. The VPD position decreases with increasing energy for 26.6, 31.7, 36.4, and 37.3 keV and increases with the energy until it reaches a plateau. The functional behavior of VPD position for the energy range 26.6-59.5 keV was attributed to the dead layer thickness of the Ge crystal. Monte Carlo simulations were performed to investigate the behavior of VPD position with various dead layer thickness ranging from 100 to 800 μm. It was seen that VPD position increases with increasing energy for 31.7, 59.5, and 80.1 keV more significant at relatively lower energies, but constant for the energies 661-1,332 keV.
- DergiSurveys in Geophysics