Earthquake imprints on a lacustrine deltaic system: The Kürk Delta along the East Anatolian Fault (Turkey)          下载免费PDF全文

Aurélia Hubert‐Ferrari  Meriam El‐Ouahabi  David Garcia‐Moreno  Ulaş Avşar  Sevgi Altınok  Sabine Schmidt  Nathalie Fagel  M. Namık Çağatay 《Sedimentology》2017,64(5):1322-1353

Deltas contain sedimentary records that are not only indicative of water‐level changes, but also particularly sensitive to earthquake shaking typically resulting in soft‐sediment‐deformation structures. The Kürk lacustrine delta lies at the south‐western extremity of Lake Hazar in eastern Turkey and is adjacent to the seismogenic East Anatolian Fault, which has generated earthquakes of magnitude 7. This study re‐evaluates water‐level changes and earthquake shaking that have affected the Kürk Delta, combining geophysical data (seismic‐reflection profiles and side‐scan sonar), remote sensing images, historical data, onland outcrops and offshore coring. The history of water‐level changes provides a temporal framework for the depositional record. In addition to the common soft‐sediment deformation documented previously, onland outcrops reveal a record of deformation (fracturing, tilt and clastic dykes) linked to large earthquake‐induced liquefactions and lateral spreading. The recurrent liquefaction structures can be used to obtain a palaeoseismological record. Five event horizons were identified that could be linked to historical earthquakes occurring in the last 1000 years along the East Anatolian Fault. Sedimentary cores sampling the most recent subaqueous sedimentation revealed the occurrence of another type of earthquake indicator. Based on radionuclide dating (¹³⁷Cs and ²¹⁰Pb), two major sedimentary events were attributed to the ad 1874 to 1875 East Anatolian Fault earthquake sequence. Their sedimentological characteristics were determined by X‐ray imagery, X‐ray diffraction, loss‐on‐ignition, grain‐size distribution and geophysical measurements. The events are interpreted to be hyperpycnal deposits linked to post‐seismic sediment reworking of earthquake‐triggered landslides.  相似文献   

Numerical modeling of groundwater resource management options in the East Oweinat area,SW Egypt   总被引：1，自引：0，他引：1  

A.?M.?EbraheemEmail author  H.?K.?Garamoon  S.?Riad  P.?Wycisk  A.?M.?Seif El Nasr 《Environmental Geology》2003,44(4):433-447

Southwest Egypt is an arid area with no surface water and limited resources of useable groundwater in the well-known Nubian Sandstone Aquifer System. These groundwater reserves have been heavily exploited since the 1960s, which has led to substantial decline in the potentiometric surface of the aquifer. A calibrated regional numerical model with refined grids on the pumping centers has been used to investigate the hydrodynamic impacts of different groundwater management options on the potentiometry of the aquifers. The results indicate that there is a real danger of either dewatering the shallow aquifer in some areas (e.g., Kharga Oasis), or increasing the water depth to uneconomic lifting depth. They also indicate that, although the planned extraction rates in Dakhla, Farafra, and Bahariya oases are feasible for at least the coming 100 years, the present rate for Kharga Oasis and the planned rate for the East Oweinat area have to be reduced substantially.  相似文献   

A Simulation Model for the Evaluation of the Electrical Power Potential Harnessed by a Marine Current Turbine     

Ben Elghali  S.E. Balme  R. Le Saux  K. El Hachemi Benbouzid  M. Charpentier  J.F. Hauville  F. 《Oceanic Engineering, IEEE Journal of》2007,32(4):786-797

This paper deals with the development of a Matlab-Simulink model of a marine current turbine system through the modeling of the resource and the rotor. The simulation model has two purposes: performances and dynamic loads evaluation in different operating conditions and control system development for turbine operation based on pitch and speed control. In this case, it is necessary to find a compromise between the simulation model accuracy and the control-loop computational speed. The blade element momentum (BEM) approach is then used for the turbine modeling. As the developed simulation model is intended to be used as a sizing and site evaluation tool for current turbine installations, it has been applied to evaluate the extractable power from the Raz de Sein (Brittany, France). Indeed, tidal current data from the Raz de Sein are used to run the simulation model over various flow regimes and yield the power capture with time.  相似文献   

On the thermal instability of a nonuniformly rotating fluid layer heated from below     

El Mekki  O.M. 《Solar physics》2001,202(1):1-9

The thermal instability both as stationary convection and overstability of a nonuniformly rotating fluid layer of vertical extent is considered. It is shown that in both types of instability the effect of the variation of the rate of rotation is to introduce a new branch to the marginal instability curves of uniform rotation which departs from them towards a zero of the Rayleigh number as the horizontal wavenumber approaches zero. The relevance to the solar interior is discussed.  相似文献   

Preface     

El–Sabh  M.I.  Venkatesh  S.  Lomnitz  C.  Murty  T.S. 《Natural Hazards》1997,16(2-3):101-102

  相似文献   

A semi-analytical method for the wave-induced seabed response     

M. S. Rahman  Khalid El-Zahaby  John Booker 《国际地质力学数值与分析法杂志》1994,18(4):213-236

A general semi-analytical method is presented for the analysis of seabed response under wave action during a storm. The seabed is idealized as a poro-elastic medium filled with a single compressible fluid with anisotropic flow. The coupled process of fluid flow and deformation of soil skeleton is formulated in the framework of Biot's theory. The analysis for the response of homogeneous seabed of finite thickness under a plane progressive wave is developed first, followed by an extension for the case of a layered seabed. A generalization for three-dimensional response of seabed is also developed for a general wave field which provides the analyses for seabed response under short-crested or standing waves in the vicinity of a structure. Some numerical examples illustrating the proposed analyses are also presented.  相似文献   

R?le du brassage et du stockage magmatique dans l’homogénéisation des granito?des calco-alcalins: Cas du pluton composite de Za?r (Maroc central)     

Jamila Ha?meur et Iz-Eddine El Amrani El Hassani 《Eclogae Geologicae Helvetiae》2005,98(2):219-236

Resume.  Le pluton calco-alcalin de Za?r est composé de trois principaux faciès pétrographiques répartis en deux unités granitiques imbriquées. Ces faciès, de différents degrés d’hybridation et de différenciation, résultent de mélanges magmatiques entre des magmas basiques mantelliques de type ?HAB? (basalte hyperalumineux) et un magma anatectique issu de la fusion partielle de matériaux crustaux (métapélites ou métagrauwackes). La répartition des faciès granitiques de Za?r peut s’expliquer selon un modèle pétrogénétique de type ?MASH? (melting-assimilation-storage-homogenization) où des magmas hybrides seraient formés suivant différentes proportions de mélanges magmatiques acide-basique. Ces magmas auraient subides conditions d’ascension spécifiques et seraient mis en place sous forme de 3 grandes injections successives:

1)	Une injection précoce de magma fortement hybride donne la granodiorite-tonalite du SW, assez faiblement homogénéisée et à grands xénolites et enclaves microgrenues mafiques (EMM) dont les compositions pétrographiques, chimiques et isotopiques initiales sont bien préservées
2)	Une injection, plus tardive et sur une longue distance, de magma relativement plus différencié, donne le monzogranite-granodiorite du NE, assez bien homogénéisé et riche en petites EMM dont les compositions ont été rééquilibrées avec celles du granite h?te
3)	Une injection très tardive après un stockage de quelques millions d’années et un important brassage magmatique ayant permis un mélange magmatique complet (mixing) des deux composants acide et basique. Cela donne le leucogranite central, très différencié et parfaitement homogène

Manuscrit re?u le 12 décembre 2003 Révision acceptée le 9 mai 2005  相似文献   

Étude de la variation spatio-temporelle des paramètres physico-chimiques caractérisant la qualité des eaux d'une lagune côtière et ses zonations écologiques : cas de Moulay Bousselham,Maroc     

Hanane Labbardi  Omar Ettahiri  Said Lazar  Zakia Massik  Said El Antri 《Comptes Rendus Geoscience》2005,337(5):505-514

Our interest is related to the hydrological characteristics of the Moulay Bousselham lagoon. Water samples were taken monthly from July 2001 to June 2002 in 15 stations distributed along the lagoon. The various measured hydrological parameters (temperature, salinity, suspended matter, chlorophyll a) showed significant monthly variations ($p<0.001$), whereas spatially among all sampled stations, only the salinity showed significant variations. The variability analysis approached by the analysis of the normalized principal components combined with discriminate analysis showed very small inter-stations variability. Its percentage is 11% and 9% of the total variance during high and low tide, respectively. To cite this article: H. Labbardi et al., C. R. Geoscience 337 (2005).  相似文献   

Environmental impacts of Baltim and Ras El Bar shore-parallel breakwater systems on the Nile delta littoral zone,Egypt     

O.?E.?FrihyEmail author  M.?M.?El Banna  A.?I.?El Kolfat 《Environmental Geology》2004,45(3):381-390

This study evaluates the impacts resulting from the construction of two large-scale detached breakwater systems on the Nile delta coast of Egypt at Baltim and Ras El Bar beaches (~18.3 km shoreline length). The two protective systems were installed in a water depth of between 3 and 4 m and consist of 17 units in total (each ~250 m long). A comprehensive monitoring program spanning the years 1990 to 2002 was implemented and included beach-nearshore profiles, grain size distribution of seabed sand and information related to the background coastal processes. Evaluation of these systems concentrates on the physical impacts on coastal morphodynamics, mitigation and their design implications. The beach and nearshore sedimentation (erosion/accretion patterns) and grain texture of seabed sediment in the study areas have been substantially disrupted due to the interruption of longshore transport by the shore-parallel detached breakwaters. Rate of shoreline and seabed changes as well as alongshore sediment volume have been substantially affected, resulting in accretion in the breakwater landward sides (tombolo or salient) followed by downdrift erosion. The preconstruction beach erosion at Baltim (–5 m/year) and at Ras El Bar (–6 m/year) has been replaced, respectively, by the formation of sand tombolo (35 m/year) and salient (9 m/year). On the other hand, beach erosion has been substantially increased in the downdrift sides of these protective systems, being –20 m/year at Baltim and –9 m/year at Ras El Bar. Further seaward, the two protective systems at Baltim and Ras El Bar have accumulated seabed sand at maximum rates of 30 and 20 cm/year and associated with downdrift erosion of –45 and –20 cm/year, respectively. Strong gyres and eddies formed in the breakwater gabs have drastically affected swimmers and subsequently caused a significant number of drownings each summer, averaging 35 and 67 victims/year at Baltim and Ras El Bar beaches, respectively. This study provides baseline information needed to help implement mitigation measures for these breakwater systems.  相似文献   

Exchange of light rare earths for Ca in apatite     

Abderrahmane Iqdari  Bruce Velde  Noureddine Benalioulhaj  Saint-Clair Dujon  Nacer El Yamine 《Comptes Rendus Geoscience》2003,335(4):381-390

Diffusion experiments were carried out on natural apatite crystals that were immersed in molten light rare earth element (REE) chloride salt at temperatures between 900 and 1150 °C for periods up to 35 days. Electron microprobe analysis of the crystals showed that light REEs replaced Ca according to electronic balance, i.e. $\text{2}\text{REE}{}^{\mathrm{3+}}$ for $\text{3}\text{Ca}{}^{\mathrm{2+}}$. These diffusion profiles indicate that a maximum amount of substitution in the structure occurs when two of the ten Ca ions in apatite are replaced by the REE diffusing elements. Anisotropic diffusion is observed between a and c crystallographic directions. Comparison of maximum distance indicates that the larger ions move more easily in the apatite structure. We conclude that the light REEs diffuse within the channel structures of the mineral, and that this diffusion is controlled by the substitution type of elements in the calcium sites. To cite this article: A. Iqdari et al., C. R. Geoscience 335 (2003).  相似文献