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Second EAGE International Conference on Engineering Geophysics
- Conference date: 24 Nov 2013 - 27 Nov 2013
- Location: Al Ain, United Arab Emirates
- ISBN: 978-90-73834-66-8
- Published: 24 November 2013
61 - 71 of 71 results
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The Characteristics of Three Different Subduction Zones in Iranian Plateau
More LessIranian plateau is a tectonically young complex region resulting from collision of Arabian Plate with Eurasia. Existence of three different subduction zones within different geographical parts provides different tectonic and geodynamic characteristics with the plateau. In this study, we use surface wave tomography method to image S-velocity structure of upper mantle and Moho depth variations across the Iranian plateau. Our results show that there is a clear evidence for subducting of Arabian plate beneath central Iran across the Zagros collisional zone in south-west Iran. Active subduction still occurs to the southeast of Iran where the oceanic part of Arabian plate is being subducted beneath Makran coast. The oceanic crust of South Caspian Basin is being westward under thrusting under Talesh and Alborz mountains in northern part of Iran
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Geo-Electric Three-Dimension Surveys for Detection of Subsurface Structures
More LessResistivity electrical changes in vertical, horizontal and in the direction that is perpendicular to the survey line, is measured in 3D surveys. 3D electric data illustrate a 3D image from subsurface layers, therefore combination of3D electric results and surface geology is appreciated as helpful technique in electric data interpretation. What Is carried out for performing a 3D survey is as follows: first a 2D survey is carried out in the survey field and then collected data are interpretated. When the subsurface layers are defined clearly, an area is selected and a suitablegrid for 3D survey is designed. After data acquisition, by using a 3D interpretation software, data points areinterpretated. Finally, the results are compared with the result of 2D configuration. In this study, the mainobjective is the detection of a fault trend by using pole–pole electrode array which is commonly used for 3Dsurveys. This survey method by using a 3D interpretation model gives accurate results of subsurface structures. In order to confirm the abilities of this method for fault detection, after checking the final results of 2D Shlumbergerarray on a fault trend in Anarak area in Esfehan province
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Investigation of Sabalan Geothermal Field Structure Magnetotelluric Method (MT)
More LessSabalan geothermal field is a high potential geothermal system in Ardebil province N-W of Iran that is now under investigation for the electricity power generation .In this paper the fourteen MT stations of 1998 MT data set were used along a profile perpendicular to the main geological structures in order to assess the three main elements of Sabalan geothermal field namely cap-rock, reservoir and heat source. TE and TM mode data and skew parameter show that the earth dimensionality differs from site to site, so we examine the joint 2D inversion along the profile. The two-dimensional inversion has been done by using a code from Siripunvaraporn and Egbert (2000).The resulting model show a pattern of high–very low–low resistivity with depth. The high resistive layer at the surface is governed to a great extent by basalt, andesitic and old trachyandesitic flows and other impermeable rocks that have thermal conduction and acts as the cap-rock of the system. The second layer is a very conductive layer and interpreted as the reservoir with thermal convection and hot fluids contained in its fractured and pores
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Geoenvironmental Studies of Contamination of Bottom Sediments of Oman Gulf, United Arab Emirates
Authors M El Tokhi, B. Mahmoud, S. Alaabed and A. MusallamHeavy metals and grain size were determined in 23 bottom samples from Gulf of Oman, UAE. Analyses of grain size revealed that most of the samples in the studied areas lie between muddy sand to gravelly sand texture. The most standard deviations in the areas reflect moderately, well sorted grain size. The high percentages sediments of the four areas lie in saltation population rather than traction and suspension population this support the results that the sediments are mixed from different environments such as fluvial, beach and shallow marine. Studying the characteristic feature for all chromatographic pattern of four samples reflect typical to weathered crude oil. The concentrations of copper, zinc, lead, iron, manganese and vanadium vary between (9.00, 17.15 , 11.62, 19812.8, 281.1 and 19.40 µg/g) respectively which are being within the permission levels. This mean that no elements derived from pollutant sources. Nickel and cadmium concentration (497.4 and 5.57 µg/g) respectively of the studied samples are shown to be high level. The contaminations level were found due to petrogenic origin and their sources are either weathered or highly weathered crude oils and or used lubricating oil. Their detection gives an indication of recent and continuous petroleum inputs.
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Characterization of a Landslide Using 2D Electrical Resistivity Tomography: Case of Akfadou at Bejaia (NE of Algeria)
Authors F. Khaldaoui, Y. Djediat, M. Djeddi, A. Ydri and F. AllguiThe slopes of the left bank of the Soummam River (Bejaia) are subject of active land movement that threatens people and the rural economy. These landslides occur on surface ruptures along geological surface. The lands involved are unstable soils supplied with flysch, marl, uncemented colluvium materials. Instabilities are sustained even in summer by surface water circulation, largely from defective pipes, which highly saturate the clay loam component materials. 2D Electrical Resistivity Tomography survey tomography was carried out to delineate Geological and geophysical results on an unstable site of this region revealed superficial discontinuity surfaces that promote surface movement of low extension with large circular cutaway within the top of the unstable area. The fracture surface was identified in colluvium formation covering the flysch.
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H on V Processing and Ground Vibration Frequencies at Mohammedia (Algiers) Site
In order to development the land additional at Mohammedia site, situated northern Algeria, near the sea, and it is one part of the project shoreline development throughout the region of Algiers, geophysical data acquisition and processing from ambient vibration noise have been made to understand the ground vibrations in terms of frequency and amplification. We are also trying to estimate the thickness of boosting layers formed mainly by embankments sometimes overcoming quaternary alluvium.
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The Use of Magnetic Method to Study the Subsurface Structures in Mubazzarah Area- Jabal Hafit, Al-Ain, United Arab Emirates
Authors A. Gabr, W. Hashem, A. Al Reesi and S. MubarakGreen Mubazarah area is a touristic area, located in Al-Ain City, UAE. This area is planned to be the site of intensive touristic constructions. Magnetic Survey has been acquired to investigate the subsurface structures in the area, which are geologically evidenced in the nearby surrounding outcrops. Total magnetic field (TF), Regional – Residual separation technique, Reduced to Magnetic pole (RTP), First derivative in X, Y, XY directions and tilt derivative have been carried out. As well as, the depths of the magnetic anomalies have been estimated. Finally, subsurface geologic structures have been presented in the final Magnetic fault trends map. Surface geological observations revealed that, the faults dissecting the nearby outcrops can be classified according to their trends into four fault-sets. The most prevailing one trends in E– W and has sinistral displacement. The subordinate fault-sets are oriented in NE-SW and NW-SE and dominate in the northern and middle part of the study area. N-S fault trend is also indicated. The magnetic anomalies show a good agreement with the surface structural trends. The depth estimation reflects shallow depths of the magnetic anomalies, which may reflect the shallow mineralized fault zones, which have been visually detected in certain locations.
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AUV for Shallow Water Hydrographic Surveys: Detecting Bedforms in Oued Loukkos Estuary (Morocco)
More LessThe images of the water-sediment surface provided by the AUV, showing dunes in different area of the loukkos river with a wavelength differs from 1 to 15 m; they are organized in series with quite the same lengths and the same wave amplitude. Another distinguishing criterion, revealed thanks to images of the water-sediment surface, seems to be the longitudinal morphology of dunes (planimetric dune morphologies). We were able to distinguish dunes with crests straight and slightly curvy form characterizing the two-dimensional dunes. Other forms of crests were distinguished, presenting the three-dimensional dunes are dunes with crest highly sinuous, catenary, linguoid, and lunate. The latter are often detected upstream or near the banks, remaining fairly stationary during the period of our study. The AUV images constitute the first step towards the understanding the distribution of different forms of dunes, in the Oued Loukkos estuary, thus well unveil the relationship between the sinuosity of dunes and hydrodynamic and sedimentary environmental conditions.
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Re-Interpretation of Airborne Electromagnetic Survey, Al Khazna Site –Al A’in District: Application for Ground Water Exploration and Regional Geology
By M. HassounehPilot Study of Helicopter airborne geophysical time-domain electromagnetics (EM) survey has been carried out over an area of 10 km2×18 km2 in Al Khazna site north of Al A’in city in 2002. The main objective of the survey was to determine the capabilities of the airborne EM survey with respect to mapping the conductivity variation of the different sedimentary units, to see if the EM data could define the aquifer horizon for the direct detection of water-bearing formations and to try and use the data to map the salinity in the region.
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Synthetic Catalog Simulation in Low Seismicity Regions Based on Monte Carlo Method (Case Study of Naien Zone)
More LessA Monte Carlo method is a technique that involves using random numbers and prob abilityto solve problems. In this method, we fix a probabilistic model which is compatible with problem or simulate the problem itself. In both state, the random parameters are built by some specific rules and the process has been done over and over. Then we analyze the problem statistically. As mentioned, Monte Carlo method uses in lots of engineering science fields. One of the uses of Monte Carlo method is in the low seismicity regions for seismic hazard analysis and catalog simulation
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Geoforensic and Legal Aspects of Site Investigations
Authors A. El Saiy, A. Aldahan, A. Murad, H. Baker, S. Hussein and A. GabrUse of geological information as clue for identifying responsibility of an engineering problem related to construction, land use and water resource management can provide significant help to the legal system. Flooding of basements in several houses in a residential area located in Al Ain city occurred in a more or less chaotic pattern. Results of the geoforensic investigationindicate that houses that are accidently built on the gravel paleochannel had their basement flooded compared to those lying outside the channel. Thus when it comes to the legal aspect of the case, then the nature geological conditions have contributed to the damage and not the construction practices.
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