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31.
In this work, some solutions of magnetohydrodynamic (MHD) equations are searched in order to investigate some large scale physical quantities in the sunspot dominated latitudinal regions near the equatorial plane. Special separation of variables is used to obtain the radial and latitudinal changes in spherical coordinates. Present parametric analysis yields three important parameters which are the sphericity, density and radial components shape parameters in the latitudinal distributions of physical variables. In the region of interest there is a considerable change in physical quantities with respect to regions where sunspots do not appear. 相似文献
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Liquefaction which is one of the most destructive ground deformations occurs during an earthquake in saturated or partially saturated silty and sandy soils, which may cause serious damages such as settlement and tilting of structures due to shear strength loss of soils. Standard (SPT) and cone (CPT) penetration tests as well as the shear wave velocity (V s)-based methods are commonly used for the determination of liquefaction potential. In this research, it was aimed to compare the SPT and V s-based liquefaction analysis methods by generating different earthquake scenarios. Accordingly, the Erci? residential area, which was mostly affected by the 2011 Van earthquake (M w = 7.1), was chosen as the model site. Erci? (Van, Turkey) and its surroundings settle on an alluvial plain which consists of silty and sandy layers with shallow groundwater level. Moreover, Çald?ran, Erci?–Kocap?nar and Van Fault Zones are the major seismic sources of the region which have a significant potential of producing large magnitude earthquakes. After liquefaction assessments, the liquefaction potential in the western part of the region and in the coastal regions nearby the Lake Van is found to be higher than the other locations. Thus, it can be stated that the soil tightness and groundwater level dominantly control the liquefaction potential. In addition, the lateral spreading and sand boiling spots observed after the 23rd October 2011 Van earthquake overlap the scenario boundaries predicted in this study. Eventually, the use of V s-based liquefaction analysis in collaboration with the SPT results is quite advantageous to assess the rate of liquefaction in a specific area. 相似文献
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İlknur Kaftan 《Acta Geophysica》2017,65(4):627-634
A genetic algorithm (GA) is an artificial intelligence method used for optimization. We applied a GA to the inversion of magnetic anomalies over a thick dike. Inversion of nonlinear geophysical problems using a GA has advantages because it does not require model gradients or well-defined initial model parameters. The evolution process consists of selection, crossover, and mutation genetic operators that look for the best fit to the observed data and a solution consisting of plausible compact sources. The efficiency of a GA on both synthetic and real magnetic anomalies of dikes by estimating model parameters, such as depth to the top of the dike (H), the half-width of the dike (B), the distance from the origin to the reference point (D), the dip of the thick dike (δ), and the susceptibility contrast (k), has been shown. For the synthetic anomaly case, it has been considered for both noise-free and noisy magnetic data. In the real case, the vertical magnetic anomaly from the Pima copper mine in Arizona, USA, and the vertical magnetic anomaly in the Bayburt–Sar?han skarn zone in northeastern Turkey have been inverted and interpreted. We compared the estimated parameters with the results of conventional inversion methods used in previous studies. We can conclude that the GA method used in this study is a useful tool for evaluating magnetic anomalies for dike models. 相似文献
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Adem Bayram Hızır Önsoy Murat Kankal Murat İhsan Kömürcü 《Arabian Journal of Geosciences》2014,7(11):4987-4996
Suspended sediment related studies based on direct measurements for Turkish rivers and streams are very few for various reasons such as cost, time, or fewer operational sediment gauging stations, and thus the researchers tend to look for indirect methods. Turkey is a developing country and in need of many investments, which resulted in engineering and management modifications in its river and stream systems. This paper investigates the spatial and temporal variations of suspended sediment concentration (SSC, mg/L) versus turbidity (NTU) in the stream Har?it watershed having a length of the main branch at 143 km and catchment area of 3,280 km2, Eastern Black Sea Basin of Turkey. Subsequently, the effect of the all kinds of anthropogenic activities was evaluated, namely, dam operation, levee construction, municipal wastewater discharge, sand–gravel mining on SSC, and turbidity in the watershed. In situ turbidity monitoring and water sampling studies were semimonthly conducted at ten stations from March 2009 to February 2010. On a semimonthly basis, it was revealed that SSC and turbidity values having significant correlation varied spatially and temporarily. The municipal wastewater discharge from the city of Gümü?hane together with the decreasing flow rate revealed itself with a significant increase in the turbidity and SSC, especially in the summer months. Torul Dam having a reservoir volume of 168 hm3 could trap 78.6 % of the SSC and could remove 66.6 % of the turbidity, thanks to its long hydraulic residence time; however, Kürtün Dam released the suspended sediment as a result of its sluiceway tunnel operation. Sand–gravel mining activities between the last two stations severely affected the water quality by increasing the SSC and turbidity. 相似文献
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İrfan Temizel 《Mineralogy and Petrology》2014,108(3):353-370
Miocene aged calc-alkaline mafic host stocks (monzogabbro) and felsic microgranular enclaves (monzosyenite) around the Bafra (Samsun) area within Tertiary volcanic and sedimentary units of the Eastern Pontides, Northeast Turkey are described for the first time in this paper. The felsic enclaves are medium to fine grained, and occur in various shapes such as, elongated, spherical to ellipsoidal, flame and/or rounded. Most enclaves show sharp and gradational contacts with the host monzogabbro, and also show distinct chilled margins in the small enclaves, indicating rapid cooling. In the host rocks, disequilibrium textures indicating mingling or mixing of coeval mafic and felsic magmas are common, such as, poikilitic and antirapakivi textures in feldspar phenocrysts, sieve textured-patchy-rounded and corroded plagioclases, clinopyroxene megacrysts mantled by bladed biotites, clinopyroxene rimmed by green hornblendes, dissolution in clinopyroxene, bladed biotite, and acicular apatite. The petrographical and geochemical contrasts between the felsic enclaves and host monzogabbros may partly be due to a consequence of extended interaction between coeval felsic and mafic magmas by mixing/mingling and diffusion. Whole-rock and Sr-Nd isotopic data suggests that the mafic host rocks and felsic enclaves are products of modified mantle-derived magmas. Moreover, the felsic magma was at near liquidus conditions when injected into the mafic host magma, and that the mafic intrusion reflects a hybrid product formed due to the mingling and partial (incomplete) mixing of these two magmas. 相似文献
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PAMUKÇU OYA GÖNENÇ TOLGA ÇIRMIK AYÇA SINDIRGI PETEK KAFTAN İLKNUR AKDEMIR ÖZER 《Journal of Earth System Science》2015,124(1):137-148
Journal of Earth System Science - The monitoring of gravity changes in a region enables the investigation of regional structural elements depending upon the changes in load compensation. This... 相似文献
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İnan Keskin 《Environmental Earth Sciences》2013,70(4):1619-1628
Disasters caused by events such as earthquake, flooding, rock falls, landslides are often encountered. However, generally, the reasons for the destructive and devastating effects of these nature events are that settlement locations were chosen without site investigation studies, or that available studies were inadequate. Such inadequacies in the field are related to inappropriate settlement location and the resulting damage caused by rock falls. This study evaluated rockfall risk in a settlement that developed in a similar manner. The study was carried out in Bo?aziçi village of Kemah (Erzincan/Turkey), which is located in a very important tectonic zone. The study site is located on the lower sections of an area with very steep cliffs and 50–75° slopes. This cliff, which is the source of rockfalls, has a slope dip of approximately 90°. The cliff comprises 25–30 m high, fractured and cracked basaltic volcanic mass. To determine block size in the study area, scanline survey measurements and block size measurements were performed on blocks that loosened and fell from the cliff face. It was found that block sizes reached 6 m3. Rockfall analyses were performed along the selected profiles using the Rockfall V.4.0 software. Kinetic energy, bounce height, horizontal location of rock end-points, and velocity of the rocks along each section were evaluated separately for each profile. This data were used to produce distribution maps for each profile and the settlement was evaluated in terms of rockfall risk. The results indicate that the study area was at risk of future rockfalls and that it would be appropriate to relocate one part of the settlement. 相似文献
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The geology and morphology of the Antakya Graben between the Amik Triple Junction and the Cyprus Arc
Ufuk Tarı Ş. Can Genç Caner İmren Bonnie A.B. Blackwell Nalan Lom 《Geodinamica Acta》2013,26(1-2):27-55
In southeastern Turkey, the NE-trending Antakya Graben forms an asymmetric depression filled by Pliocene marine siliciclastic sediment, Pleistocene to Recent fluvial terrace sediment, and alluvium. Along the Mediterranean coast of the graben, marine terrace deposits sit at different elevations ranging from 2 to 180 m above present sea level, with ages ranging from MIS 2 to 11. A multisegmented, dominantly sinistral fault lying along the graben may connect the Cyprus Arc in the west to the Amik Triple Junction on the Dead Sea Fault (DSF) in the east. Normal faults, which are younger than the sinistral ones, bound the graben’s southeastern margin. The westward escape of the continental ?skenderun Block, delimited by sinistral fault segments belonging to the DSF in the east and the Eastern Anatolian Fault in the north caused the development of a sinistral transtensional tectonic regime, which has opened the Antakya Graben since the Pliocene. In the later stages of this opening, normal faults developed along the southeastern margin that caused the graben to tilt to the southwest, leading to differential uplift of Mediterranean coastal terraces. Most of these normal faults remain active. In addition to these tectonic movements, Pleistocene sea level changes in the Mediterranean affected the geomorphological evolution of the area. 相似文献