The Erzincan earthquake of 13 March 1992 in Eastern Turkey: tectonic aspects     

Vladimir G. Trifonov  M. Salih Bayractutan  Arkadiy S. Karakhanian  Tamara P. Ivanova 《地学学报》1993,5(2):184-189

The tectonic significance of the Erzincan earthquake of 13 March, 1992 in Eastern Turkey is discussed. The intersection of the North Anatolian and The East Anatolian strike-slip fault zones has resulted in formation of the Erzincan pull-apart basin and new seismically active fault branches on its northeastern side. Local concentrations of surface ruptures strike along the most active branches of the North Anatolian fault zone (N300W) for 62 km. They are usually open fractures with northeastern sides uplifted up to 20 cm and rarely with dextral offset up to 10 cm. These secondary ruptures manifest indirectly oblique seismic fault displacement corresponding to the Late Quaternary motion on the fault zone, although at the surface the dextral component has been suppressed relative to the vertical one.  相似文献   

Changes in soil properties following conversion of Acacia senegal plantation to other land management systems in North Kordofan State,Sudan     

B.A. El Tahir  D.M. Ahmed  J. Ardö  A.M. Gaafar  A.A. Salih 《Journal of Arid Environments》2009,73(4-5):499-505

Changes in soil texture, bulk density, pH, concentrations and stocks of OC, N, P and K before and after conversion of a 6-year-old Acacia senegal plantation to other land management systems (LMS) were investigated, after three cropping seasons, in the drylands of western Sudan. LMS included pure and intercropped sorghum (PS), roselle (PR) and grasses (PG) with A. senegal at high- and low-tree densities (HD 433 and LD 266 trees ha^?1). Significant changes included increase in coarse sand and a decrease in fine sand under pure and intercropped systems at LD; decrease in clay contents in PS and PR; an increase in clay ratio in all pure crops and HD + R; a decrease in aggregated mean concentrations of OC, N and P under all LMS by 42%, 68% and 45%, respectively; increase in soil pH under all LMS; a depletion of aggregated mean stocks of OC, N, P and K in all LMS by 38%, 30%, 52% 13%, respectively. The study established that wholesale tree clearance constitutes a major cause of soil degradation, and tree inputs and cycling of nutrients are of major importance to soil fertility in the study area.  相似文献   

WAVECALC: an Excel-VBA spreadsheet to model the characteristics of fully developed waves and their influence on bottom sediments in different water depths   总被引：2，自引：2，他引：0  

Jacobus P. Le Roux  Zeki Demirbilek  Marysia Brodalka  Burghard W. Flemming 《Geo-Marine Letters》2010,30(5):549-560

The generation and growth of waves in deep water is controlled by winds blowing over the sea surface. In fully developed sea states, where winds and waves are in equilibrium, wave parameters may be calculated directly from the wind velocity. We provide an Excel spreadsheet to compute the wave period, length, height and celerity, as well as horizontal and vertical particle velocities for any water depth, bottom slope, and distance below the reference water level. The wave profile and propagation can also be visualized for any water depth, modeling the sea surface change from sinusoidal to trochoidal and finally cnoidal profiles into shallow water. Bedload entrainment is estimated under both the wave crest and the trough, using the horizontal water particle velocity at the top of the boundary layer. The calculations are programmed in an Excel file called WAVECALC, which is available online to authorized users. Although many of the recently published formulas are based on theoretical arguments, the values agree well with several existing theories and limited field and laboratory observations. WAVECALC is a user-friendly program intended for sedimentologists, coastal engineers and oceanographers, as well as marine ecologists and biologists. It provides a rapid means to calculate many wave characteristics required in coastal and shallow marine studies, and can also serve as an educational tool.  相似文献   

Cloud Models for Solar Faculae     

Eker  Zeki 《Solar physics》2003,212(2):277-300

Assuming the clouds as plane parallel structures above the photosphere, center-to-limb contrast variations of various cloud models for solar faculae with approximations such as optically thin or thick, hot or cold, and with or without surface reflections, have been investigated. It has been found that the observed facular contrast data from Frazier (1971) and Taylor et al. (1998) at the 525 nm continuum is best represented by a cloud which is 230 K hotter than the undisturbed photosphere, with an optical depth =0.4283, and with isotropic surface reflections causing 11% of the background photons to be lost before penetrating into the cloud. This model and some other cloud models are shown to provide a fit better than the other physical and non-physical facular models presented previously.  相似文献   

Active faulting and natural hazards in Armenia, eastern Turkey and northwestern Iran   总被引：1，自引：0，他引：1  

Arkady S. Karakhanian  Vladimir G. Trifonov  Herve Philip  Ara Avagyan  Khaled Hessami  Farshad Jamali  M. Salih Bayraktutan  H. Bagdassarian  S. Arakelian  V. Davtian  A. Adilkhanyan 《Tectonophysics》2004,380(3-4):189-219

Active fault zones of Armenia, SE Turkey and NW Iran present a diverse set of interrelated natural hazards. Three regional case studies in this cross-border zone are examined to show how earthquakes interact with other hazards to increase the risk of natural disaster. In northern Armenia, a combination of several natural and man-made phenomena (earthquakes, landslides and unstable dams with toxic wastes) along the Pambak-Sevan-Sunik fault (PSSF) zone lowers from 0.4 to 0.2–0.3g the maximum permissible level (MPL) of seismic hazard that may induce disastrous destruction and loss of life in the adjacent Vanadzor depression.

In the Ararat depression, a large active fault-bounded pull-apart basin at the junction of borders of Armenia, Turkey, Iran and Azerbaijan, an earthquake in 1840 was accompanied by an eruption of Ararat Volcano, lahars, landslides, floods, soil subsidence and liquefaction. The case study demonstrates that natural hazards that are secondary with respect to earthquakes may considerably increase the damage and the casualties and increase the risk associated with the seismic impact.

The North Tabriz–Gailatu fault system poses a high seismic hazard to the border areas of NW Iran, eastern Turkey, Nakhichevan (Azerbaijan) and southern Armenia. Right-lateral strike–slip motions along the North Tabriz fault have given rise to strong earthquakes, which threaten the city of Tabriz with its population of 1.2 million.

The examples illustrate how the concentration of natural hazards in active fault zones increases the risk associated with strong earthquakes in Armenia, eastern Turkey and NW Iran. This generally occurs across the junctions of international borders. Hence, the transboundary character of active faults requires transboundary cooperation in the study and mitigation of the natural risk.  相似文献   

Iron mineralization in the Garagu Formation of Gara Mountain,Duhok Governorate,Kurdistan, NE Iraq: geochemistry,mineralogy and origin     

Tola?A.?Mirza  Ibrahim?M.?J.?MohialdeenEmail author  Salih?M.?Awadh 《Arabian Journal of Geosciences》2016,9(6):473

The iron mineralization is hosted in carbonate beds of the Garagu Formation (Early Cretaceous) at Gara Mountain, Duhok Governorate, Kurdistan Region, NE Iraq. The Garagu Formation is composed of a series of limestone and siltstone beds with iron-rich beds in the middle part. The iron-rich limestones are iron-rich oolitic grainstone and bioclastic wackestone with hematite and goethite minerals. Geochemical results drawn from this study indicate that the percentage of iron in these beds reaches 19.73 %. Moreover, petrographical investigation of thin and polished sections reveals the presence of different types of fossils, indicating an open marine interior platform depositional environment. Different iron minerals, including hematite, goethite, siderite, pyrite and magnetite, were identified in the sections, and their geneses were related to syngenetic and diagenetic processes. The geochemical distribution of major and trace elements, as well as the V/Ni, V/(V+Ni), V/Cr and Sr/Ba ratios, indicates a reducing environment during the precipitation of carbonate sediments and a subsequent oxidizing condition during the concentration of iron minerals via diagenesis.  相似文献   

Dynamic Response of Pile Reinforced Soils and Piled Foundations     

Salah Messioud  Umur Salih Okyay  Badreddine Sbartai  Daniel Dias 《Geotechnical and Geological Engineering》2016,34(3):789-805

The rigid-pile soil-improvement technique aims to increase the bearing capacity of the soil and decrease the settlement of the surface structure. The most remarkable difference of this technique from the deep-foundation system is the soil layer between the pile heads and the structure. This soil layer, called the mattress, is made of compacted granular materials and participates in the load transfer through arching and shear mechanisms. In order to understand the dynamic behavior of rigid-pile reinforced soils, tri-dimensional finite-element analyses of a soil-pile-slab system, a soil-pile-mattress-slab system, and a soil-pile-mattress-embankment system are presented in this paper. Different geometric configurations are studied in terms of dynamic impedances. The soil, piles, mattress, and embankment are represented as continuum solids, and the slab is represented by structural plate-type elements. The horizontal and vertical impedances of pile foundations are presented and the results are compared with studies in the literature. This study shows the influence of the mattress stiffness, the geometrical configuration, and head/tip fixity conditions on the dynamic response of the foundation system. A comparison between rigid piles and pile foundations is then presented.  相似文献   

Energy dissipation in sloshing waves in a rolling rectangular tank—I. Mathematical theory     

Zeki Demirbilek 《Ocean Engineering》1983,10(5):347-358

The hydrodynamic aspects of the motion of a viscous fluid having a free surface in a rolling tank have been investigated. In a sequence of three papers, an analytical technique together with a numerical solution method will be presented to describe the sloshing phenomenon accurately and efficiently. This first paper introduces a linear theory of viscous liquid sloshing and formulates a boundary value problem subject to appropriate conditions. Viscosity is included in the problem formulation and its effects are properly accounted for. The second paper will describe a solution of the problem in function space by the truncation of infinite series. Boundary conditions are satisfied through the use of Fourier series expansions. However, the no-slip condition at the side walls can also be treated in a least-squares sense.Among the results that will be reported in the third paper are the effects of viscosity on liquid sloshing phenomenon and the dependence of viscous dissipation on the Reynolds and Froude numbers. Furthermore, the influence of the tank aspect ratio on viscous dissipation has been explored. These results demonstrate some unknown features of the functional relationships that exist between the dissipated energy and the Reynolds and Froude numbers. Similarly, the dependence of the dissipated energy on the aspect ratio has been analytically studied. The results obtained agree with the physical laws for the range of parameters investigated.  相似文献   

Geometrical properties of perfect breaking waves on composite breakwaters     

M. Salih Kirkgz  M. Sami Akz 《Ocean Engineering》2005,32(16):1994-2006

The experimental results have so far shown that when a wave breaks on a vertical wall with an almost vertical front face at the instant of impact that is called perfect breaking or perfect impact, the greatest impact forces are produced on the wall. Therefore, the configuration of breaking waves is important in the design considerations of coastal structures. The present study is concerned with determining the geometrical properties of oscillatory waves that break perfectly on the vertical wall of composite-type breakwaters. The laboratory tests for perfect breaking waves on composite breakwaters are conducted with base slopes of 1/2, 1/4 and 1/6, and with berm widths of 0.00, 0.10, 0.20, 0.30 and 0.40 m. The shape and the dimensions of waves at the instant of perfect breaking on the wall are determined using a video camera. The experimental results for the geometrical properties of the breakers are presented non-dimensionally. Within the range of present experimental conditions, it is found that the dimensionless breaker crest height, h_b/d_w, and dimensionless breaker height, H_b/d_w, decrease; and, dimensionless breaker depth, d_w/H₀, increases with increasing relative berm width, B/D. The breaker height index, H_b/H₀, is almost unaffected by B/D. The deep-water wave steepness and the base slope of the breakwater do not seem to influence the geometrical properties of the breakers at wall systematically.  相似文献   

A detached binary system BK Pegasi     

Osman Demircan  Yalçin Kaya  Zeki Tüfekçioğlu 《Astrophysics and Space Science》1994,222(1-2):213-223

TheUBV photometry of the detached F-type eclipsing binary BK Pegasi is presented. The light curve solution by a simple spherical model assumption suggests that a slightly hotter, larger and more luminous primary was eclipsed during the primary minimum. Combined with the radial velocity curves in Popper (1983), it was used to determine anew the system's parameters. The age and the metal abundance of the system were estimated as (3.3 ± 0.2) × 10⁹ yr andz = 0.028 ± 0.003 from a comparison with the new grids of stellar models and the isochrones by Schalleret al. (1993). The distance of the system was estimated as 290 pc.  相似文献