Some Probabilistic and Statistical Properties of the Seismic Regime of Zemmouri (Algeria) Seismoactive Zone

Statistical tests have been used to adjust the Zemmouri seismic data using a distribution function. The Pareto law has been used and the probabilities of various expected earthquakes were computed. A mathematical expression giving the quantiles was established. The extreme values limiting law confirmed the accuracy of the adjustment method. Using the moment magnitude scale, a probabilistic model was made to predict the occurrences of strong earthquakes. The seismic structure has been characterized by the slope of the recurrence plot γ, fractal dimension D, concentration parameter K_sr, Hurst exponents H_r and H_t. The values of D, γ, K_sr, H_r, and H_t diminished many months before the principal seismic shock (M = 6.9) of the studied seismoactive zone has occurred. Three stages of the deformation of the geophysical medium are manifested in the variation of the coefficient G% of the clustering of minor seismic events.     

Effect of temperature on the physical precursors of rock block failure

The influence of temperature (25–400 °C) on the variations of mechanical, acoustic, electric and electromagnetic precursors of rock failure has been shown experimentally. The most significant variations were detected in the principal parameters of the acoustic and electromagnetic emissions whose impulse energy underwent a fast growth. However, the general character of hierarchical evolution stages of micro and macrofailure was practically unchanged. This has been confirmed by the so-called concentration parameter of rupture, which is theoretically calculated and checked in experiments; its space-time variations preceding the occurrence and progression of macrofailure are slightly depending on the rock temperature effect. This has been shown through the convolution of some physical precursors in a complex parameter whose variation showed an approaching of macrofailure, which remains slightly influenced by changes in temperature. Our results are interpreted in relation to physics of superficial earthquakes and precursors.     

Attenuation of ground vibrations due to different technical sources

The attenuation of technically induced surface waves is studied theoretically and experimentally.In this paper, nineteen measurements of ground vibrations induced by eight different technical sources including road and rail traffic, vibratory and impulsive construction work or pile driving, explosions, hammer impulses and mass drops are described, and it is shown that the technically induced ground vibrations exhibit a power-law attenuation v～r-q where the exponents q are in the range of 0.5 to 2.0 and depend on the source types.Comparisons performed demonstrate that the measured exponents are considerably higher than theoretically expected.Some potential effects on ground vibration attenuation are theoretically analyzed.The most important effect is due to the material or scattering damping.Each frequency component is attenuated exponentially as exp(-kr), but for a broad-band excitation, the sum of the exponential laws also yields a power law but with a high exponent.Additional effects are discussed, for example the dispersion of the Rayleigh wave due to soil layering, which yields an additional exponent of 0.5 in cases of impulsive loading.     

Integrating an artificial intelligence approach with k-means clustering to model groundwater salinity: the case of Gaza coastal aquifer (Palestine)

Artificial intelligence (AI) techniques have increasingly become efficient alternative modeling tools in the water resources field, particularly when the modeled process is influenced by complex and interrelated variables. In this study, two AI techniques—artificial neural networks (ANNs) and support vector machine (SVM)—were employed to achieve deeper understanding of the salinization process (represented by chloride concentration) in complex coastal aquifers influenced by various salinity sources. Both models were trained using 11 years of groundwater quality data from 22 municipal wells in Khan Younis Governorate, Gaza, Palestine. Both techniques showed satisfactory prediction performance, where the mean absolute percentage error (MAPE) and correlation coefficient (R) for the test data set were, respectively, about 4.5 and 99.8% for the ANNs model, and 4.6 and 99.7% for SVM model. The performances of the developed models were further noticeably improved through preprocessing the wells data set using a k-means clustering method, then conducting AI techniques separately for each cluster. The developed models with clustered data were associated with higher performance, easiness and simplicity. They can be employed as an analytical tool to investigate the influence of input variables on coastal aquifer salinity, which is of great importance for understanding salinization processes, leading to more effective water-resources-related planning and decision making.     

Retention of a heavy metal by marl collected from aquifer substratum

One of the objectives of this work is to characterize marl samples collected from the bedrock aquifer (at 30 m depth) of Wadi Al Ghoula located in Draria southwest of Algiers. The other objective is to make a kinetics study, linear and non-linear isotherm study, and mass transfer study of the adsorption of copper onto marl in aqueous solution. The fitness of kinetics and isotherm models was evaluated by using some error analysis function. One of the major results using an XRF technique is an evidence of the presence of calcite in the weight of 13.82%. The XRD patterns of these samples confirmed the presence of montmorillonite, kaolinite, illite, calcite, and quartz. On the other hand, the FTIR analysis clarified the presence of calcite. The specific surface area of 20,999 m²/g was obtained using the BET, which indicates that the material has a predominance for the mesoporous character. The instrumental neutron activation analysis (INAA), a nondestructive method, gives the elemental composition of the adsorbent. Based on the value of the coefficient of determination, the adsorption kinetics of copper in aqueous solution using marl as adsorbent follows the pseudo-second-order model. And according to the value of the coefficient of determination obtained for the two models, the intraparticle diffusion and liquid film diffusion control the process of adsorption of copper onto marl with low predominance for the second model of diffusion in the first stage of adsorption. The linear and the non-linear treatments of the two-parameter isotherm models (Langmuir, Freundlish, Temkin) show that the fitting best model of isotherm is the empirical Freundlish isotherm. For the three-parameter isotherm models (Toth, Sips, and Redlish-Peterson), the Sips model is the more accurate fitting model than the two other isotherms in the non-linear approach. Some error analysis functions are used to choose the best results.     

Contents of Volume 7

Volume Contents

Contents of Volume 7     

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

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).     

Study of Shoreline Changes Through Digital Shoreline Analysis System and Wave Modeling: Case of the Sandy Coast of Bou-Ismail Bay,Algeria

Ocean Science Journal - This work aims to analyze the evolution of Bou-Ismail coastline in Algeria using aerial photographs and quick-bird satellite image during the elapsed period from 1959 to...