Late quaternary seismic stratigraphy and active faults of the Gulf of İzmit (NE Marmara Sea)

The Upper Quaternary seismic stratigraphy and active faults of the Gulf of İzmit were investigated by means of high-resolution shallow seismic profiling data in the source region of 1999 İzmit earthquake. High-resolution seismic reflection data correlated with borehole data indicate that the stratigraphy of İzmit Bay consists of three distinct depositional sequences formed in response to middle Pleistocene-Holocene sea-level changes. Reflector R, separating the pre-Holocene sequences (1 and 2) from the Holocene sequence (3), represents an erosional unconformity produced by the subaerial fluvial erosion of the continental shelves at the time of the last glacial maximum. Occasional, anomalous reflections (acoustic turbidity) observed within the Holocene sequence are interpreted as gas accumulations. The maximum thickness of the Holocene sediments is found to be about 25 m. The isopach map of Holocene sediment implies that the thickness of the Holocene decreases from the east towards the central and western basins of İzmit Bay. Two distinct fault systems are interpreted in İzmit Bay. The main fault system extending roughly in an E-W direction along the Gulf of İzmit is an active right lateral strike slip fault with a normal component. The secondary faults are normal faults striking in different directions and these are identified as being both active and inactive. In addition, prominent compressive features are identified in the seismic cross-sections of some profiles acquired to the east of Hersek Peninsula where the focal mechanisms of the aftershocks of the 1999 İzmit earthquake also reveal predominantly reverse faulting mechanisms, as identified by a local dense seismic network.     

A reconnaissance report for the Romanian earthquake of 4 March 1977

The engineering aspects of the 4 March 1977 Romanian earthquake are presented. They are based upon a field investigation conducted by the writers in Bucharest and in southern Romania in collaboration with members of the Building Research Institute of Romania, during the period 25–31 March 1977. This report covers general observations, data and evaluation on the character of the earthquake, structural damage inflicted by it, performance of different types of buildings during the earthquake and relief operations.     

Pretreatment of Olive Oil Mill Wastewater by Two Different Applications of Fenton Oxidation Processes

The removal of chemical oxygen demand (COD) and phenol from olive oil mill wastewaters (OOMW) was investigated experimentally by using conventional Fenton (CFP) and Fenton type processes (FTP) with zero valent iron (ZVI). Different operational parameters such as initial pH, Fe²⁺, Fe⁰, and H₂O₂ concentrations were examined. Kinetic studies in terms of COD and phenol removals for both CFP and FTP were performed. The original pH value (4.6) of OOMW for CFP was found as the optimum pH. The determined optimum conditions are [Fe²⁺] = 1500 mg L^?1, [H₂O₂] = 1750 mg L^?1, and pH = 4.6 for CFP; [Fe⁰] = 2000 mg L^?1, [H₂O₂] = 2000 mg L^?1, and pH = 3 for FTP. 82.4% COD and 62% phenol removals were performed under the optimum conditions by CFP, while 82% COD and 63.4% phenol were removed by FTP. According to the results of kinetic studies, it was observed that COD and phenol were removed by FTP more rapidly, compared to CFP. Consequently, it was determined that both CFP and FTP were effective processes for the pretreatment of OOMW.     

Support vector regression for estimating earthquake response spectra

This study uses support vector regression (SVR), a supervised machine learning algorithm, to model the average horizontal response spectrum as a nonparametric function of a set of predictor ground motion variables. Traditional ground motion prediction equations (GMPEs) are derived using parametric regression, where a fixed functional form is selected, and the model coefficients are determined by minimizing the errors on the training set. The SVR model is nonparametric; there is no need to assume a fixed functional form. Using nonlinear basis functions, the data points are mapped into a high dimensional feature space, where nonlinear input-output relationships can be expressed as a linear combination of nonlinear functions, using a subset of the data points. The combination weights are determined by minimizing the generalization error, using a formal mechanism to characterize the trade-off between the model complexity and the quality of fit to the data. Minimization of the generalization error instead of the fitting error leads to better generation to unseen data, and thus reduces the risk of over-fitting for a given number of data points. The SVR model is not based on a specific probability distribution, and is readily applicable to non-Gaussian data. An example application is presented for vertical strike-slip earthquakes, and the predictions from the SVR model are compared to the recently developed GMPEs. The results demonstrate the validity of the proposed model, and suggest that it can be used as an alternative to the conventional ground motion prediction models.     

Sustainable development and management of an aquifer system in western Turkey

This study presents the establishment of sustainable development and management policies for the Küçük Menderes River Basin aquifer system in western Turkey. Geological, hydrogeological, and geophysical data are used conjunctively to define various hydrogeological units and their geometry. Distributions of hydraulic-parameter values and recharge are estimated by geostatistical methods and hydrologic simulations, respectively. A finite-difference groundwater flow model is used to represent the unconfined flow in the aquifer system. The model has been calibrated under steady state and transient conditions. The resulting model was used to test seven management scenarios for a planning period of 21 years to determine the so-called safe yield and sustainable yield of the aquifer system and to investigate the potential impacts of four planned surface water reservoirs on groundwater resources in the basin. The results demonstrate that the continuation of the present pumping rates exceeds both the safe yield and the sustainable yield of the aquifer system. Consequently, the growing need for irrigation water should be met by the construction of the planned surface water reservoirs and the implementation of efficient water management policies and plans.

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Resumen Este estudio presenta el establecimiento de políticas sustentables de desarrollo y gestión en el sistema acuífero de la cuenca del río Küçük Menderes, al Oeste de Turquía, para lo que se ha utilizado datos geológicos, hidrogeológicos y geofísicos de forma conjunta de cara a definir diversas unidades hidrogeológicas y su geometría. La distribución de los parámetros hidráulicos y de la recarga ha sido estimada mediante métodos geoestadísticos y simulaciones hidrológicas, respectivamente. Se ha empleado un modelo de las aguas subterráneas en diferencias finitas para representar el flujo no confinado en el sistema acuífero, el cual se ha calibrado bajo condiciones estacionarias y transitorias. El modelo resultante ha sido usado para contrastar siete escenarios de gestión durante un período de planificación de 21 años con el fin de determinar el punto de explotación segura y sustentable del sistema acuífero, así como para investigar los impactos potenciales sobre los recursos subterráneos de los cuatro embalses superficiales que se hallan en proyecto. Los resultados demuestran que el mantenimiento de las tasas actuales de extracción del acuífero supera tanto el régimen de bombeo seguro como el sustentable del sistema. Por consiguiente, se debería compensar la necesidad creciente de agua para riego con la construcción de los reservorios superficiales previstos y con la implementación de políticas y planes de gestión eficiente del agua.

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Résumé Cette étude présente la proposition dune politique de développement et de gestion durables du système aquifère du bassin du Petit Mendérès dans louest de la Turquie. Des données géologiques, hydrogéologiques et géophysiques ont été utilisées conjointement pour définir les différentes unités hydrogéologiques et leur géométrie. Les distributions des paramètres hydrauliques et de la recharge ont été estimées respectivement par des méthodes géostatistiques et des simulations hydrologiques. Un modèle découlement souterrain aux éléments finis a été utilisé pour représenter lécoulement non captif dans le système aquifère. Le modèle a été calibré dans des conditions de régimes permanent et transitoire. Le modèle résultant a servi à tester sept scénarios de gestion pour une période de programmation de 21 ans, afin de déterminer les débits de prélèvement sûr et durable dans le système aquifère et détudier les impacts potentiels de quatre réservoirs deau de surface en projet sur les eaux souterraines du bassin. Les résultats montrent que la poursuite des prélèvements au débit actuel excède aussi bien le débit dexploitation de sécurité que celui durable pour le système aquifère. Par conséquent, les besoins croissants deau pour lirrigation doivent être satisfaits par la construction des réservoirs projetés et par la mise en place de politiques et de plans de gestion de leau efficace.

     

Biosorption of Dyes by Natural and Activated Vine Stem. Interaction between Biosorbent and Dye

In the present study, the vine stem and modified vine stem were used as low cost adsorbents for the removal of acidic and basic dyes from aqueous solutions. A comparative study was also carried out with activated carbon obtained from vine stem and then the adsorption capacities of all adsorbents were evaluated by batch adsorption process. The effects of various adsorption parameters (initial pH, particle size, and contact time) were investigated. The modification of the vine stem with nitric acid increased its adsorption capacity for the basic dye. Both, vine stem and modified vine stem exhibited higher adsorption capacities than activated carbon. The adsorption capacities were found to be 322.58, 250, and 200 mg g^?1 for modified, natural vine stem, and activated carbon, respectively. In the case of acidic dye, the pH strongly affected the adsorption capacity and the maximum dye uptake was observed at pH 2 for all adsorbents. The acidic dye adsorption was lower compared to basic dye on both biosorbents and activated carbon tested. The maximum acidic dye adsorption values (58.82 and 59.88 mg g^?1) were obtained with the vine stem and activated carbon, respectively. In the case of lignocellulosic adsorbents, both surface charge and surface groups had main effect on the adsorption of basic dye, while adsorption mechanism in activated carbon was mainly through the physical adsorption. The results of comparative adsorption capacity of adsorbents indicated that vine stem or modified vine stem can be used as a low cost alternative to activated carbon in aqueous solution for basic dye removal.     

Oreganum Stalks as a New Biosorbent to Remove Textile Dyes from Aqueous Solutions

In the present study, Oreganum onites L. stalks in natural and chemically modified with HNO³ and H³PO⁴ used as adsorbent for removal of both acidic and basic dyes from waters. The adsorption was studied as a function of pH and contact time by batch method. All tested biosorbents were characterized by FT‐IR, scanning electron microscopy, and measuring the pH dependence of the zeta potential. The adsorption isotherms were fitted to Langmuir isotherm. The maximum adsorption capacity of dyes was 280.73 mg g^?1 for Basic Red 18, 147.06 mg g^?1 for methylene blue and 112.36 for Acid Red 111, which is comparable to that of other lignocellulosic materials. The modification process was considerably increased the biosorption capacity of lignocellulosic material, resulting in a 56–63% increase in the biosorption capacity of basic dyes and a 125% increase in the biosorption capacity of acidic dye. The present study illustrated that the most effective factors in the adsorption of basic dye were surface charge and acidic groups on lignocellulosic biosorbents, while non‐electrostatic forces as well as electrostatic forces were also effective in the adsorption of acidic dye. In conclusion, Oreganum stalks can be considered as a very prospective adsorbent for the removal of tested basic and acidic dyes.     

A nonparametric characterization of vertical ground motion effects

Design guidelines have traditionally oversimplified the vertical ground motion effects by defining a constant vertical‐to‐horizontal response spectral ratio (V/H). With the recognition that such practice is not always conservative, recent studies have proposed improvements to the representation of vertical seismic effects in design codes, based on empirical ground motion relations. Conventional empirical modeling requires selecting the functional form of the predictive model. Because of the complicated nature of ground motions, identification of the underlying function is a challenge. A related drawback to this approach is its high susceptibility to overfitting, especially with today's highly complex models. To address these issues, this paper proposes a nonparametric approach to characterize the vertical seismic effects. Using support vector machines, the V/H ratio is determined without an assumed functional form. The accuracy of the model is measured by adopting an epsilon‐insensitive residual function with a regularization term added to prevent overfitting. An example application using ground motion records from strike‐slip and normal faulting earthquakes is presented, and the results are compared with a current empirical model, for different magnitude, distance, and local soil conditions. The median V/H estimates from the two models are shown to be in good general agreement. The standard deviation estimates from the proposed model are consistently larger than the estimates from the empirical model. The results from this study show that the proposed method is a viable alternative and offers the opportunity to characterize vertical seismic effects without an assumed functional form. Copyright © 2011 John Wiley & Sons, Ltd.     

Removal of hexavalent chromium from aqueous solution by barium ion cross-linked alginate beads

Barium ion cross-linked alginate beads have shown great affinity to toxic hexavalent chromium ions in aqueous solution, in contrast to the traditionally used calcium alginate beads. Our adsorption experiments were carried out by the batch contact method. The optimal pH for removal was found to be pH 4. The equilibrium was established in 4 h, and the removal efficiency of chromium(VI) was found to be 95 %. The adsorption data were applied to Langmuir, Freundlich, Dubinin–Redushkevich (D–R), and Temkin isotherm equations. Both Langmuir and Freundlich isotherm constants indicated a favorable adsorption. The value of mean sorption energy calculated from D–R isoterm indicates that the adsorption is essentially physical. The high maximum chromium(VI) adsorption capacity was determined from the Langmuir isotherm as 36.5 mg/g dry alginate beads. The chromium(VI) adsorption data were analyzed using several kinetic models such as the pseudo-first-order, pseudo-second-order, intraparticle diffusion, and Elovich models, and the rate constants were quantified. Our study suggests that barium alginate beads can be used as cost-effective and efficient adsorbents for the removal of chromium(VI) from contaminated waters.     

Continuous resistivity profiling survey in Mersin Harbour, Northeastern Mediterranean Sea

No detailed information has previously been available on the geological and geophysical characteristics of the sea floor and the underlying strata of Mersin Harbour, Northeastern Mediterranean Sea (Turkey). Continuous resistivity profiling (CRP) and borehole data from Mersin Harbour were used to interpret geoelectric stratigraphy of Neogene-Quaternary sediments in the area. This represents one of few such detailed case studies that have applied these valuable CRP techniques for the purpose of marine stratigraphic imaging. It was found that the Neogene-Quaternary sedimentary succession in the area consists of three geoelectric units (GU1, GU2, and GU3 from base to top). The lowest unit, GU1, has a resistivity value of greater than 20.0 ohm-m and consists of Miocene aged limestone and marl. The middle unit, GU2, is characterized by resistivity values ranging from 3.0 to 20.0 ohm-m. Its thickness is greater than 90 m, with the upper section being composed of stiff clay sequences which are Plio-Pleistocene in age. The uppermost unit, GU3, has resistivity values varying from 1.0 to 3.0 ohm-m. This unit displays a maximum thickness of 15 m, and is composed of Holocene muds together with gravel, sand, silt and clay (sometimes incorporating shells) materials of the Plio-Pleistocene age and their various mixtures, silty/clay limestone, and conglomerate sandstone. Comparisons of the geoelectric units with the depositional sequences interpreted from the available seismic data outwith, but close to, Mersin Harbour reveal that the geoelectric unit GU3 corresponds to the depositional sequences C (mainly Holocene) and B (mainly Plio-Pleistocene). The geoelectric unit GU2 partly correlates with the depositional sequence B which appears to be Plio-Pleistocene in age. The geoelectric unit GU1, which has not been encountered in previous seismic surveys, is a new discovery within Mersin Harbour. Limited correlation between the seismic and resistivity structures in the study area is attributed to differences in the acoustic impedance and resistivity contrasts of sub-bottom layers, as well as the penetration versus resolution performance of the systems.