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21.
Electron spin resonance (ESR) and 230Th/234U ages of speleothem samples collected from karstic caves located around 3000 m elevation in the Alada?lar Mountain Range (AMR), south-central Turkey, were determined in order to provide new insight and information regarding late Pleistocene climate. ESR ages were validated with the 230Th/234U ages of test samples. The ESR ages of 21 different layers of six speleothem samples were found to range mostly between about 59 and 4 ka, which cover the Marine Oxygen Isotope Stages (MIS) MIS 3 to MIS 1. Among all, only six layers appear to have deposited during MIS 8 and 5. Most of the samples dated were deposited during the late glacial stage (MIS 2). It appears that a cooler climate with a perennial and steady recharge was more conducive to speleothem development rather than a warmer climate with seasonal recharge in the AMR during the late Quaternary. This argument supports previous findings that suggest a two -fold increase in last glacial maximum mean precipitation in Turkey with respect to the present value. 相似文献
22.
Seismic risk assessment of buildings in Izmir,Turkey 总被引：1，自引：1，他引：0
Izmir, the third largest city and a major economic center in Turkey, has more than three million residents and half million
buildings. In this study, the seismic risk in reinforced concrete buildings that dominate the building inventory in Izmir
is investigated through multiple approaches. Five typical reinforced concrete buildings were designed, modeled and assessed
for seismic vulnerability. The sample structures represent typical existing reinforced concrete hospital, school, public,
and residential buildings in Izmir. The seismic assessments of the considered structures indicate that they are vulnerable
to damage during expected future earthquakes. 相似文献
23.
Hayrullah Karabulut Zafeiria Roumelioti Christoforos Benetatos Ahu Kmec Mutlu Serdar
zalaybey Mustafa Aktar Anastasia Kiratzi 《Tectonophysics》2006,412(3-4):195-216
The July 2003 sequence in the Gulf of Saros (Northeastern Aegean Sea) is investigated, in terms of accurate event locations and source properties of the largest events. The distribution of epicenters shows the activation of a 25-km long zone, which extends in depth between 9 and 20 km. The major slip patch of the 6 July 2003 Mw 5.7 mainshock is confined in a small area (45 km2), which coincides with the deeper (12–20 km) part of the activated zone. The epicenters of the sequence follow the northern margin of the Saros depression. This observation supports recent studies, according to which the continuation of the Ganos fault in the Gulf of Saros does not coincide with the fault along the northern coast of the Gelibolu peninsula, but it is located at the northern boundary of the Saros depression. This is further supported by the fact that the focal mechanisms of the mainshock and of the largest aftershocks of the 2003 sequence imply almost pure dextral strike-slip faulting, whereas the fault bounding the Gulf of Saros to the south appears as a normal fault on seismic sections. Thus, we infer that the principle deformation zone consists of a major strike-slip fault, which lies close to the northern margin of the Saros depression and this fault could be regarded as the continuation of the northern branch of the North Anatolian Fault into the Saros Gulf and North Aegean Trough as suggested by regional tectonic models. The northeastern extent of the 2003 sequence marks the western termination (at 26.3° E) of a long-term seismic quiescence observed in the period following the 1912 Ganos earthquake, which may be associated with the extend of the rupture of the particular earthquake. 相似文献
24.
Submarine and coastal karstic groundwater discharges along the southwestern Mediterranean coast of Turkey 总被引：1，自引：1，他引：0
C. Serdar Bayari N. Nur Ozyurt Mehmet Oztan Yalin Bastanlar Guzden Varinlioglu Hayati Koyuncu Haldun Ulkenli Serdar Hamarat 《Hydrogeology Journal》2011,19(2):399-414
A 120 km-long part of the southwestern coast of Turkey, with well-developed karst terrain in contact with the sea, has been investigated by systematic diving surveys to determine the submarine groundwater discharges (SGDs). The physical, chemical and isotopic data have been used to determine the rate of the fresh groundwater end member (FEM) and its temporal dynamics. About 150 SGDs have been detected by diving surveys employed mostly up to a depth of 30 m below sea level (bsl). Among those, 15 SGDs are in the form of coastal or submarine caves with entrances ranging between sea surface and 40 m bsl. The FEM contribution in SGDs ranges from a few percent to more than 80%. Stable isotope data suggest a range of mean recharge area elevations extending from the coast to more than 1,000 m inland. In many of the SGDs, the FEMs are characterized by tritium-based residence times ranging from recent to several decades. Hypothetical geochemical calculations of mixing between freshwater and seawater end members reveal that more than 45% of freshwater contribution is required for karst development in the SGDs. Models suggest a threshold pH of 7.6 or lower for the carbonate rock dissolution. 相似文献
25.
Ali Haydar Kayhan Kasım Armagan Korkmaz Ayhan Irfanoglu 《Soil Dynamics and Earthquake Engineering》2011
In this study, a solution model is proposed to obtain input ground motion datasets compatible with given design spectra based on meta-heuristic harmony search algorithm. The utility of the solution model is demonstrated by generating ground motion datasets matching the Eurocode-8 design spectra for different soil types out of an extensive database of recorded motions. A total of 352 records are selected from the Pacific Earthquake Engineering Center (PEER) Strong Motion Database based on magnitude, distance, and site conditions to form the original ground motion domain. Then, the proposed harmony search based solution algorithm is applied on the pre-selected 352 time-series to obtain the ground motion record sets compatible with design spectra. The results demonstrate that the proposed HS based solution model provides an efficient way to develop input ground motion record sets that are consistent with code-based design spectra. 相似文献
26.
Earthquake disaster risk assessment and evaluation for Turkey 总被引：3，自引：0，他引：3
Kasım Armağan Korkmaz 《Environmental Geology》2009,57(2):307-320
Turkey is the one country in which 90% of the buildings are subject to the risk of earthquake disaster. Recent earthquakes
revealed that Turkey’s present residential reinforced-concrete constructions are insufficient in earthquake resistance. Many
of the buildings which collapsed or were severely damaged have been rehabilitated by applying simple methods, whose adequacy
is questionable. As in Japan and the United States, Turkey’s earthquake assessment studies have increased, especially after
earthquakes in 1999, In US, several methodologies and standards, such as Hazard-US (HAZUS) and Applied Technology Council
(ATC) 13-20-21 and 156, provide comprehensive earthquake loss estimation methodology for post-earthquake assessment. This
paper provides post-earthquake assessment and disaster management for Turkey. The main aim of the post-earthquake assessment
discussed is to evaluate loss and estimate damage through disaster management approach. Classification criteria for damage
are essential to determine the situation after an earthquake in both the short and long terms. The methodology includes probabilistic-based
analysis, which considers the magnitude of Ms ≥ 5.0 earthquakes between 1900 and 2005, for determining the probabilistic seismic
hazard for Turkey. 相似文献
27.
Understanding the development of collapse dolines is crucially important because sudden formation of these landforms threatens property and life. Obruks are mega collapse dolines developed in the lacustrine Neogene carbonates of the Konya Closed Basin in central Turkey. These landforms with diameters and depths reaching several hundreds of meters are characterized by their cylindrical or inverted truncated cone shaped surface morphology and contain lakes if they intersect the local water table. Evaluations based on geological, geophysical, hydrogeological data and the groundwater’s chemical and isotopic compositions suggest a hypogenic mechanism for the development of obruks. This process seems to be driven by the upward migration of a deep-seated carbon dioxide flux from an intrusive magmatic body. Presence of volcanogenic elements (i.e. Li and F) and remarkably high dissolved carbon dioxide (logPCO2?=?10?1 atm) in fresh groundwater, hydrothermal springs with elevated He contents (R/Ra?=?4.77), highly enriched carbon-13 isotopic composition of total dissolved inorganic carbon (13C_TDIC?=??1.12 ‰ V-PDB) in the regional groundwater and presence of widespread carbon dioxide discharges, constitute apparent evidence for the hypogenic fluid migration into the Neogene aquifer where enhanced dissolution due to mixing between the shallow-fresh and deep-saline groundwaters gives rise to obruk formation. 相似文献
28.
Mihriban Şahin Mehmet Emin Korkmaz Osman Agar Abdullah Dirican 《Environmental Earth Sciences》2017,76(3):121
A screening of natural radioactivity content has been carried out in thermal water samples collected from surrounding of Central Anatolia, Turkey. The concentration levels of gross alpha and beta of 19 different samples has been determined using the low background gas-flow proportional counter. The measured gross alpha and beta activities in waters range from 0.11 to 16 Bq/L and 0.10 to 16.9 Bq/L, respectively. The measured values of gross alpha and beta concentrations are compared to previous studies in the literature and recommend WHO guideline activity concentration. The data resulting from the measurement have been statistically analyzed. 相似文献
29.
A series of red tides were observed during 2015 in the Izmit Bay(the Marmara Sea) which is located in the most industrialized and populated region of Turkey. Six samplings were carried out in this area following the red tides.Nitrite-N, nitrate-N, ammonia, silica and orthophosphate concentrations were analyzed spectrophotometrically.Physicochemical conditions were measured by CTD probe. Plankton quantification was performed using counting chambers under microscopes. Prorocentrum micans was the most abundant species, except on May 14,2015, when Noctiluca scintillans was dominant. The abundance of P. micans reached average 18×10~6 ind./L on May 3, 2015 in the Karamürsel station, simultaneously with elevated levels of NH_3 and o-PO_4~(3–). The sample was also abundant in dead amphipods((72±12) ind./L) that had been covered by mucilage aggregates produced by P.micans. The highest biomass(calculated by carbon) was recorded as(268±26.0) mg/L on May 14 in the Hereke station. Beside the anthropogenic wastewater discharges, unknown sources and resuspensions caused increases in nutrient levels. After long term northeaster gusts(35 km/h for 5 d) an upwelling occurred on November 6, 2015 after wind-induced sediment resuspension. Although nutrient discharges remarkably decreased over 30 years through established wastewater treatment plants, harmful phytoplankton blooms still occur. Comparing the present results with other studies in nearby Mediterranean seas reveals that the most intense harmful dinoflagellate bloom in recent years occurred in the Izmit Bay. Therefore, additional protection measures necessary for a cleaner Izmit Bay. These incidents also demonstrate that contaminants, accumulated in sediment,may have long-lasting effects on enclosed marine ecosystems. 相似文献
30.
There are two objectives to this paper. First, a chattering-free sliding-mode controller is proposed for the trajectory control of remotely operated vehicles (ROVs). Second, a new approach for thrust allocation is proposed that is based on minimizing the largest individual component of the thrust manifold. With regards to the former, a new adaptive term is developed that eliminates the high-frequency control action inherent in a conventional sliding-mode controller. As opposed to the common adaptive approach, the new adaptive term does not require the linearity condition on the dynamic parameters and the creation of a regressor matrix. In addition, it removes the need for a priori knowledge of upper bounds on uncertainties in the dynamic parameters of the ROV. With regards to the latter, it is demonstrated that minimizing the l∞ norm (infinity-norm) of the thrust manifold ensures low individual thruster forces. The new control and thrust allocation concepts are implemented in numerical simulations of a work class ROV, and the chattering-free nature of the controller is demonstrated during typical ROV manoeuvres. In the simulation studies, the l∞ norm-based thrust allocation problem is cast as a linear programming problem that allows direct incorporation of the thruster saturation limits and a fault-tolerant property. To achieve real-time solution rates for the l∞ norm-based thrust allocation problem, a recurrent neural network is designed. In the simulation studies, the l∞ norm-based thrust allocation provides smaller maximum absolute value of the largest component of the thrust manifold than that of a conventional l2 norm (2-norm) minimization, satisfies the saturation limits of each thruster, and accommodates faults that are introduced arbitrarily during the manoeuvre. 相似文献