Geotechnical site investigations for possible urban extensions at Suez City, Egypt using GIS

With the development of economic activities in the world, the construction activities have also increased. A proper surface and subsurface investigation is made to assess the general suitability of the site and to prepare an adequate and economic safe design for the proposed work. The main purpose of the current study is to create a spatial model of the geotechnical conditions and considerations by using geographic information systems (GIS) techniques to develop and analyze a site model and to plan site activities at the new extension of Suez City (SC). In the geotechnical site evaluations, GIS can be used in four ways, data integration, data visualization and analysis, planning and summarizing site activities, and data presentation. The integrated data can be displayed; manipulated and analyzed using tools build into the GIS programs, thus creating the geotechnical site model of the study area. Decisions can be made for further site activities and the results of the site activities can be integrated into the GIS site model. Interpretation of geotechnical data frequently involves assimilating information from many sites each with a unique geographical location. Interpretation of these data requires the spatial location to incorporate into the analysis. Weights are assigned to different of mechanical, physical soil properties, geological, hydrogeological, and other ancillary data. Finally, the weighted maps are integrated using a GIS based on the construction purposes for the new extension of SC for significant cost savings in design, construction and longevity. The ideal and good zones’ highest regime has been observed towards central and western regions with sporadic pockets. The marginal zones to average zones are moderately suited for shallow foundation.     

Siliceous and organic-rich sedimentation during the Cenomanian–Turonian Oceanic Anoxic Event (OAE2) on the northern margin of Africa: an evidence from the Bargou area, Tunisia

The late Cenomanian–early Turonian deposits in Tunisia recording the OAE2 event are commonly attributed to the Bahloul Formation. These deposits are composed of dark clayey limestone and organic-rich black shales with abundant planktic foraminifera. At the Bargou area, Oued Kharroub section, these organic-rich deposits include siliceous beds with abundant radiolarians recalling the “Livello Bonarelli”. A total of 25 radiolarian species are identified with a maximum of 18 species per sample. Moreover, the species skeleton preservation is usually poor to moderate in the most studied samples [estimated preservation index (PI) values ranging between 4 and 6]. Two successive assemblages are distinguished. The oldest one (R_I) is dominated by nassellarians, which includes mainly Stichomitra, Pseudodictyomitra and Rhopalosyringium genera. It is included within the upper part of foraminiferal Rotalipora cushmani Zone and lower part of Whiteinella archaeocretacea zone. In contrast, the youngest assemblage (R_II), which belongs to the upper part of the W. archaeocretacea zone and the earliest Turonian Watinoceras ammonite assemblage, is dominated by spumellarians and includes mainly Archaeocenosphaera, Cavaspongia, Pseudoeucyrtis and Pyramispongia genera. In addition, major and trace elements are analysed to test whether the geochemical record was synchronous to the biotic event or not. Thus, selected crossplots, Al₂O₃ vs. SiO₂ and Al₂O₃ vs. TiO₂, are used to evaluate the detrital input, and V/Cr vs. V/(V?+?Ni) and U/Th vs. V/(V?+?Ni) are used to evaluate the bottom redox conditions and the primary productivity within the Bahloul Formation. A strong Si/Al increase is marked in the lower part of the siliceous and organic-rich Bahloul Formation that could be explained by a local increase in upwelling-related biogenic SiO₂ (silica-secreting organisms). Relative low abundance of terrigenous-related Ti/Al and K/Al ratios and enrichment of some productivity proxies such as Ba (organic matter related trace elements) suggests that the Bahloul was of relatively elevated primary productivity and minimal detrital input. Enrichments in redox-sensitive trace metals U and V in the Bahloul Formation deposits and redox indices, such as V/(V?+?Ni), U/Th and V/Cr, indicate that oxygen-restricted conditions prevailed during the late Cenomanian–earliest Turonian times and correlate well with relative abundances of some radiolarian and foraminiferal paleo-environmental indicators. In addition, indicators of detrital flux variations are used. Al₂O₃ shows a slight positive correlation with TiO₂ and a less distinct correlation with SiO₂.     

Fractal dynamics of geomagnetic storms

We explore fluctuations of the horizontal component of the Earth’s magnetic field to identify scaling behaviour of the temporal variability in geomagnetic data recorded by the Intermagnet observatories during the solar cycle 23 (years 1996 to 2005). In this work, we use the remarkable ability of scaling wavelet exponents to highlight the singularities associated with discontinuities present in the magnetograms obtained at two magnetic observatories for six intense magnetic storms, including the sudden storm commencements of 14 July 2000, 29–31 October and 20–21 November 2003. In the active intervals that occurred during geomagnetic storms, we observe a rapid and unidirectional change in the spectral scaling exponent at the time of storm onset. The corresponding fractal features suggest that the dynamics of the whole time series is similar to that of a fractional Brownian motion. Our findings point to an evident relatively sudden change related to the emergence of persistency of the fractal power exponent fluctuations precedes an intense magnetic storm. These first results could be useful in the framework of extreme events prediction studies.     

A wavelet-based multifractal analysis of seismic data for facies identification. Application on the pilot KTB borehole

The main goal of this paper is to identify reflection from seismic data using the multifractal formalism. Firstly, the wavelet transform modulus maxima lines method is applied with a sliding window of 128 samples at the seismic seismogram data. After that, we estimate the generalized fractal dimension. Application at the noisy synthetic seismic seismogram of the pilot Kontinentales Tiefbohrprogramm de Bundesreplik Deutschland borehole shows that the three fractal dimensions related to the three first moments are a good tool that can separate between reflection dues to the change of facies and random noise.     

Modeling and risk assessment of landslides using fuzzy logic. Application on the slopes of the Algerian Tell (Algeria)

Natural risk regains the notion of exposure to natural disaster or dangers of any natural hazard. Its management consists in the assessment and the anticipation of risks, as well as to the setting up of an alert system. From natural risk, we mentioned one bound to landslides in natural slopes that are difficult to surround and approach. Nevertheless, the assessment of landslides risk is the object of several works of research and many models, based on the multicriteria analysis, have been established. It should be noted that based on multicriteria approach, we evaluated, in a previous work, the landslide risk using the weighted sum model. The results reveal that the use of qualitative parameters influenced the classification of slope. This led us to adopt fuzzy logic approaches for assessment. This work examines the contribution of fuzzy sets theory to modeling and assessment of landslides risk in natural slopes. It brought to use this approach that permits the survey of these imprecision in adopting a Mamdani model. The method has been applied on slopes, situated in four areas of the Algerian Tell, where each is characterized by the different natural conditions. The result, put in evidence, summarizes modeling and risk assessment of landslides in an optimal classification of slopes according to the degree of instability risk. It allows decision makers to put in strategies for possible work of these slopes.     

On the application of GPR for locating underground utilities in urban areas

With the rapid growth of complex network of different types of underground utility under large cities, the need of a noninvasive technique capable of swiftly and precisely detecting these utilities in such a noisy urban environment increases. Ground-penetrating radar (GPR) is considered one of the most promising techniques in this field. This study presents the experience of GPR data acquisition, processing, and interpretation in three cities located along the coast of the Red Sea. These cities are Jeddah in Saudi Arabia and Sharm El-Sheikh and Qusier in Egypt. Data acquisition parameters varied in the three cities based on site conditions, target characteristics, and equipment availability. The processing flows were kept simple to avoid introducing artifacts to the collected data. The results show that despite the difference in site conditions and survey parameters among the three cities, with the exception of fiber optic cable, GPR technique is capable of detecting different kinds of underground utilities and precisely determine the extension, diameter, and depth of burial of these utilities.     

The utilization of seismic interpretation to identify and describe the shallow subsurface structures in the southeastern Mediterranean Sea

The shallow subsurface structures of the offshore Nile Delta particularly in the southeastern Mediterranean were dealt through the interpretation of 40 two-dimensional seismic reflection lines. The interpretations of seismic reflection data indicated that the principle sedimentary processes affecting the study area include three main structural groups according to their origin and development. The first group of structures comprises of gravity-driven structures, which include slides, slumps, turbidities, and debris flow. Slides are present in three different forms on seismic sections: slide sheets, slides with scar, and wedges of slide materials. Slumps have many geometrical shapes: lenses, spoon-shaped slumps, and slumped blocks bound by growth faults. Debris flows are present as transparent unit (due to the dispersion of seismic waves at debris boundaries), whereas turbidities appear on the seismic profiles, which are formed of closely spaced parallel thin reflectors analogous to their thin stratified bedded layers. The second group of structures is syn-depositional structures, which include growth faults, and tilted and rotated fault blocks. Growth faults are listric in shape and usually dip seaward; displacements along the fault plane increase with depth. Some of these faults are incipient, and some are complicated and intersected by secondary antithetic faults. Most of the growth faults soles out basin wards and in the evaporites layer. Fault blocks are formed due to the Messinian evaporite movement vertically and horizontally due to its mobility as a consequence to the pressure resulted from the overloading of Pliocene sediment. The third group of structures comprises evaporite flow structures such as diapiric structures and graben collapse structures. The surface of the Messinian evaporites was folded during its flow as a consequence to the lateral compression acted on the mobile strata of the Messinian evaporites to form diapiric triangular structures and creates a stress zone faulting and fractures system. These conditions led to the formation of collapse structures or graben collapse structures.     

Mineralogy, fluid inclusion, and oxygen isotope constraints on the genesis of the Lalla Zahra W-(Cu) deposit, Alouana district, northeastern Morocco

The Lalla Zahra W-(Cu) prospect of northeastern Morocco is hosted in a Devonian volcaniclastic and metasedimentary sequence composed of graywacke, siltstone, pelite, and shale interlayered with minor tuff and mudstone. Intrusion of the 284?±?7 Ma Alouana concentrically zoned, two micas, calc-alkaline, and post-collisional Alouana granitoid pluton has contact metamorphosed the host rocks, giving rise to a metamorphic assemblage of quartz, plagioclase, biotite, muscovite, chlorite, and alusite, and cordierite. The mineralization occurs in and along subvertical, 20 to 40 cm thick, and structurally controlled tensional veins composed of quartz accompanied by molybdenite, wolframite, scheelite, base metal sulphides, carbonates, barite, and fluorite. Three main stages of mineralization (I, II, and III), each characterized by a specific mineral assemblage and/or texture, are recognized. Quartz dominates in all the veins and commonly displays multiple stages of vein filling and brecciation, and a variety of textures. The early tungsten-bearing stage consists of quartz-1, tourmaline, muscovite, wolframite, scheelite, and molybdenite. With advancing paragenetic sequence, the mineralogy of the veins shifted from stage I tungsten-bearing mineralization through stage II, dominated by base metal sulphides, to stage III with late barren carbonates and barite?±?fluorite mineral assemblages. Pervasive hydrothermal alteration affected, to varying degrees, the Alouana intrusion, resulting in microclinization, albitization, episyenitization, and greisenization of all the granitic units. Fluid inclusion data yield homogenization temperatures ranging from 124°C to 447°C for calculated salinity estimates in the range of 0.4 to ~60 wt% NaCl equiv. Similarly, the δ¹⁸O values for the three generations of quartz range from 11.7‰ to 13.9‰ V-SMOW. Calculated δ¹⁸O values of the parent fluid in the range between ?3‰ and +9‰ V-SMOW are consistent either with a mixture of water of different origins, including magmatic water, or an origin from seawater or meteoric water that probably exchanged oxygen with rocks at elevated temperatures. The coexistence of CO₂-rich and H₂O-rich fluid inclusions reflect the presence of a boiling fluid associated with the deposition of the early tungsten-bearing stage mineralization at relatively high temperature. The general temperature and salinity decrease with advancing paragenetic sequence suggest that the early high temperature, magmatic, highly saline, and boiling fluid mixed with meteoric non-boiling fluid results in the precipitation of base metal sulphide and carbonate–barite stage mineral assemblages, respectively.     

Structural and geomorphic features accommodating groundwater of Al-Madinah City, Saudi Arabia

Al-Madinah City is located in the western part of Saudi Arabia on the Arabian Shield. The area underwent several tectonic events that developed its structural and geomorphic features, such as the Infracambrian Najd strike-slip faults, development of the Cenozoic basaltic flows of Northern Harrat Rahat, and Cenozoic N–S and E–W transtensional faults, related to the Red Sea rifting. These successive events formed a deltaic-shaped basin of Al-Madinah. The Al-Madinah basin is part of a 400?×?150-km² Wadi Qanah–Al-Hamd watershed, which exhibits mainly parallel drainage pattern. Sub-basins, within the main basin, exhibit trellised and radial drainage patterns. The trellised drainage pattern reflects control of the Cenozoic faults, whereas the radial drainage pattern reflects volcanic-related system. Rotation of the Arabian Plate after several extensional events that lead to the opening of the Red Sea influenced the drainage flow to be going from east to west. This geological history that include eruption, normal faulting, and erosion prior to and during the Red Sea rifting formed relief inversion geomorphology of Tertiary basalts that cap Precambrian rocks of the Ayr and Jammah Mountains in western Al-Madinah. The groundwater in the central area is part of the northern Harrat Rahat basaltic aquifer in which the groundwater level rises up in the central area due to the blocking of groundwater flow by constructions below the central area and due to reduced groundwater abstraction. Building a dam 60 km northwest of Al-Madinah would preserve more surface water than the Al-Bayda dam, in which all main valleys join in at the suggested location.     

Imaging soil moisture using GPR tomography and reflection field experiments

We performed GPR tomography and GPR reflection field experiments using a 500-MHz antenna to image relative soil moisture distribution around a poplar tree at the botanic garden of Kiel University, Kiel, Germany. The GPR tomography field experiment is carried out in two consecutive phases in order to obtain ray paths traveling from all directions and intensively covering the target. The radar tomographic data are inverted using the authors’ developed software code SeismoRad based on the finite difference technique. The attained Root-Mean-Square (RMS) errors after 200 iterations between the measured and calculated times range between 1.066 and 5.7 % in the two tomography experiments. The estimated GPR velocities range between 5.3 and 15.1 cm/ns. Two low-GPR velocity zones could be delineated coinciding with the locations of the tree root zone and a previously excavated sector. The high water saturation zone around the tree root system is found to be the main reason for such a decrease in GPR velocity. Interpretation of the two phases proved that the coverage of ray paths from all directions is important to delineate the effect of the poplar tree root system and hence to obtain accurate tomographic results. Furthermore, four GPR reflection lines are performed along the sides of the four trenches such that the antenna is moved longitudinally in the trenches and the radargrams are recorded along the horizontal xy-plane parallel to the ground surface. On the processed GPR reflection radargrams, relatively high-amplitude GPR anomalies could be outlined and are attributed to the boundary between the saturated and wet zones where different water contents affect the GPR velocity. Comparable results are obtained between the tomogram and the radar reflection results with respect to zones of increase in water content.