Investigation of Hydrodynamic Parameters and the Effects of Breakwaters During the 2011 Great East Japan Tsunami in Kamaishi Bay     

Ceren Ozer Sozdinler  Ahmet Cevdet Yalciner  Andrey Zaytsev  Anawat Suppasri  Fumihiko Imamura 《Pure and Applied Geophysics》2015,172(12):3473-3491

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Multi-disciplinary earthquake researches in Western Turkey: Hints to select sites to study geochemical transients associated to seismicity     

Sedat İnan  Kadriye Ertekin  Cemil Seyis  Şakir Şimşek  Furkan Kulak  Aynur Dikbaş  Onur Tan  Semih Ergintav  Rahşan Çakmak  Ahmet Yörük  Muhiddin Çergel  Hakan Yakan  Hüseyin Karakuş  Ruhi Saatçilar  Zafer Akçiğ  Yıldız İravul  Bekir Tüzel 《Acta Geophysica》2010,58(5):767-813

Warm and hot spring water as well as soil gas radon release patterns have been monitored in the Aegean Extensional Province of Western Turkey, alongside regional seismic events, providing a multi-disciplinary approach. In the study period of 20 months, seven moderate earthquakes with M _L between 4.0 and 4.7 occurred in this seismically very active region; two earthquakes with magnitude 5.0 also occurred near the study area. Seismic monitoring showed no foreshock activity. By contrast, hydro-geochemical anomalies were found prior to these seismic events, each lasting for weeks. The anomalies occurred foremost in conjunction with dip-slip events and seem to support the dilatancy and water diffusion hypothesis. Increased soil gas radon release was recorded before earthquakes associated with strike-slip faults, but no soil radon anomalies were seen before earthquakes associated with dip-slip faults. Geochemical anomalies were also noticeably absent at some springs throughout the postulated deformation zones of impending earthquakes. The reason for this discrepancy might be due to stress/strain anisotropies.  相似文献   

Investigation of the nature of slip surface using geochemical analyses and 2-D electrical resistivity tomography: a case study from Lapseki area, NW Turkey     

Ahmet Evren Erginal  Beyhan Öztürk  Yunus Levent Ekinci  Alper Demirci 《Environmental Geology》2009,58(6):1167-1175

The nature and subsurface structure of the slip surface of a landslide was studied on the basis of geochemical analyses and 2-D electrical resistivity tomography (ERT) survey. Head scarp and lateral slip surfaces of the landslide marked by clear slickensided shear planes were composed of the average amounts of clayey silt (32.5%) and sand (67.5%). Energy dispersive X-ray spectroscopy (EDX) data revealed the enrichment of Si (23.24%), Fe (12.2%), Al (9.51%) and C (8.34%) in the elemental composition of the disturbed slip surface. From X-ray diffractometry (XRD) data, six main clay types were determined, such as Volkonskoite, Halloysite, Ferrosilite, Saponite, Illite and Nontronite. The ERT survey displayed that the landslide developed as a reactivation on the upper part of an old landslide body.  相似文献   

Evaluation of andesite source as armourstone for a rubble mound breakwater (Hisarönü, Turkey)     

Utku Ahmet Ozden  Tamer Topal 《Environmental Earth Sciences》2009,59(1):39-49

Black Sea coast line is a hazardous region especially in winter due to the dominant wave action. Therefore, rubble mound breakwaters protected with armourstone used as ship shelters are vital structures especially for the fishermen. The deterioration of the armourstone with time in the form of abrasion and disintegration may result in the failure of the breakwater. In this study, the properties of the armourstone taken from an andesite quarry and used in the Hisarönü rubble mound breakwater were studied both in field and laboratory in order to assess their qualities and long-term durabilities. Based on the in situ observations and laboratory tests, the andesite is found to be generally marginal rock. CIRIA/CUR, RDI_s, RERS and Wet-Dry strength ratio classifications are in good agreement with the in situ observations and the results of the laboratory tests. However, RDI_d, Average Pore Diameter and Saturation Coefficient classifications cannot correctly predict long-term durability of the armourstone. Field studies reveal that block size of the andesite in the quarry increases with depth due to the increase in spacing of the cooling joints of the rock.  相似文献   

Interpretation of magnetic anomalies of dikes using correlation factors   总被引：1，自引：0，他引：1  

Ibrahim Kara  Mustafa Özdemir  F. Ahmet Yüksel 《Pure and Applied Geophysics》1996,147(4):777-788

The magnetic anomaly due to a buried dike consists of the sum of two easily separated elementary functions. These functions, which have simple symmetry, are called even and odd functions. The correlation factors (r _0,1 for the even andr _0,2 for the odd function) between least-squares residual anomalies from even and odd functions are computed. Correlation values are used to determine the depth to the top and the half-width of the dike. The method also includes the determination of the index parameter and the amplitude coefficient. The validity of the method is tested against a theoretical and a field example where the parameters of the latter were determined by other investigators in comparing the results.  相似文献   

Delta formation at the southern entrance of Istanbul Strait (Marmara sea, Turkey): a new interpretation based on high-resolution seismic stratigraphy     

Erkan Gökaşan  Oya Algan  Hüseyin Tur  Engin Meriç  Ahmet Türker  Mehmet Şimşek 《Geo-Marine Letters》2005,25(6):370-377

A detailed stratigraphic investigation based on high-resolution seismic profiles revealed that the delta at the southern entrance of the Istanbul Strait consists of three parasequence sets. The lowermost parasequence shows a sea-level stillstand at the beginning of the lowstand systems tract, possibly at 11,000±1,100 a b.p., whereas the upper two parasequences reflect deposition at lowstand and during the subsequent transgression. A maximum flooding surface may be developing on the delta at present. The delta is located on the eastern side of the Istanbul Strait canyon, with east–west prograding parasequences. The development of the delta is clearly associated with the Kurbağalı Stream on the east coast, and not with the Black Sea outflow through the strait. The geometry of the delta indicates a radial architecture arranged from northeast to southwest.  相似文献   

Evidence and implications of massive erosion along the Strait of İstanbul (Bosphorus)     

Erkan Gökaşan  Hüseyin Tur  Berkan Ecevitoğlu  Tolga Görüm  Ahmet Türker  Buğser Tok  Faruk Çağlak  Halim Birkan  Mehmet Şimşek 《Geo-Marine Letters》2005,25(5):324-342

The Strait of İstanbul (SoI) (Bosphorus) is a narrow valley, which has evolved tectonically from a stream, and in which thick sediment deposits have accumulated in the course of its evolution. Detailed seismic and multi-beam bathymetric data have revealed that the upper parts of the deeper channel deposits consist of parallel strata, which have mostly been eroded subsequently to their deposition. The resulting erosion surface is represented by the present channel floor in the strait, the estimated volume of the eroded material being approximately 2×10⁸ m³ . Erosion rate and seafloor morphology indicate that the flow direction was from the south to the north. This inner channel may have been formed by an abrupt flooding of the Black Sea by Mediterranean waters at the beginning of the latest connection between the Marmara and the Black seas. Subsequently, the Mediterranean bottom current of the modern two-way flow system, which was established at about 5–4 ka b.p., has given the latest shape to the strait floor.  相似文献   

Measurement and evaluation of the hydrodynamics and secondary currents in and near a strait connecting large water bodies—A field study     

I&#x;khan Güler  Yal&#x;n Yüksel  Ahmet Cevdet Yal&#x;ner  Esin evik  Christian Ingerslev 《Ocean Engineering》2006,33(13):1718-1748

The straits connect two large water bodies show highly strong and stratified currents related to meteorological, morphological and hydrodynamic conditions. In some cases, spatial and temporal changes of the stratified currents and their thickness, direction and magnitude are so complex. This complexity directly affects the circulation pattern in the region, water exchange between both ends of the straits and migration of fish species. In order to understand general characteristics of this kind of straits and identifying the complexity of the hydrodynamics of the region and evaluate the secondary currents and recirculation need long term, intensive, field work and measurement studies. As an example of this kind of hydrodynamically complex straits, Bosphorus strait is selected for a field study. The Bosphorus strait has a strongly stratified two-layer system and a unique case of the maximal exchange regime typical of strait flows, which is largely determined by conditions at the Black Sea. Although the Bosphorus strait has distinct two-layer stratification with an associated two-layer system exchange, no continuous current measurements have been made so far, previous measurements all having been random sampling.In this paper, a detailed measurement program has been applied to Bosphorus strait. In the measurement program, a short-term current profile measurement at selected locations at southern part of the strait has been conveyed. Additionally a long-term measurement of current profile has been performed at a selected critical location (in front of the Dolmabahçe Palace) where a recirculation flow exists in the strait. The scope of this paper is to present the techniques and the results of analysis of measurement data. In the measurements the current profile (magnitude and direction) has been determined at every 1 m depth intervals from the surface to the sea bottom at 3 min duration at every hour. Measurements provide that lower-layer flows in northward direction from the Sea of Marmara towards the Black Sea, whereas the upper-layer flow comes from the Black Sea and flows towards the Sea of Marmara in the opposite direction of lower layer. The Bosphorus strait exhibits distinctive features associated with variations in its width and depth. The meandering features of Bosphorus also cause recirculation flows. These results of measurements are presented, discussed and compared with previous studies.  相似文献   

Temporal changes of soft-bottom zoobenthic communities in and around Alsancak Harbor (Izmir Bay, Aegean Sea), with special attention to the autecology of exotic species     

Melih Ertan Çinar  Tuncer Katagan  Bilal Öztürk  Özdemir Egemen  Zeki Ergen  Ahmet Kocatas  Mesut Önen  Fevzi Kirkim  Kerem Bakir  Güley Kurt  Ertan Dagli  Asli Kaymakçi  Sermin Açik  Alper Dogan  & Tahir Özcan 《Marine Ecology》2006,27(3):229-246

Temporal and spatial variation in soft‐bottom benthic communities following recovery from a pollution episode were studied between January and September 2004 in and around Alsancak Harbor, located in the polluted part of Izmir Bay (Aegean Sea, eastern Mediterranean). Samples were collected at seven stations by van Veen grab. Three additional stations were sampled by means of a beam trawl to take into account large mobile animals and for a better estimate of the local biodiversity. A total of 231 species belonging to 10 zoobenthic groups were found. Polychaetes contributed 90% of the total faunal populations and mollusks 87% of the total biomass in the area. Community parameters varied significantly among stations and sampling periods; number of species ranged from 2 to 79 per 0.1 m² grab sample; density from 20 to 81,720 ind·m^?2; biomass from 0.1 to 4190 g·m^?2; Shannon–Wiener diversity index (log₂ base) from 0.4 to 4.4; and Pielou's evenness index from 0.11 to 1.0. Collections indicate that a number of species, including those sensitive to pollution, have colonized the area where azoic conditions had been previously reported. A total of six exotic species, Streblospio gynobranchiata, Polydora cornuta, Hydroides dianthus, Hydroides elegans, Anadara demiri and Fulvia fragilis, probably transferred to the area via ballast water or hull fouling, dominated soft or hard substrata in and near Alsancak Harbor. The first two species accounted for more than 70% of the total population in the area, while A. demiri contributed the most to the biomass (93%, at station 7).  相似文献   

Effects of the adjacent evaporitic formations on groundwater quality of alluvial sand–gravel aquifers: a study in the Derincay basin (north-central Turkey)     

Ahmet Apaydin 《Environmental Earth Sciences》2016,75(7):573

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