Electrical structure of the tectonically active Kalabsha Fault, Aswan, Egypt

Mekkawi, Mahmoud; Schnegg, Pierre-André; Arafa-Hamed, Tarek; Elathy, Essam

doi:10.1016/j.epsl.2005.09.035

Cited by 15 publications

(4 citation statements)

References 26 publications

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“…Brasse and Rath, 1997;Mekkawi et al, 2007) just as detailed studies of active shallow fault zones which pose a risk for nearby towns and settlements (e.g. Mekkawi et al, 2005;Mekkawi, 2007). A substantial amount of MT data has been collected for geothermal energy exploration throughout the East African rift in Tanzania and Ethiopia (e.g.…”

Section: Introductionmentioning

confidence: 99%

Making and Breaking of a Continent: Following the Scent of Geodynamic Imprints on the African Continent Using Electromagnetics

Weckmann

2011

Surv Geophys

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The African continent inherits a long history of continental accretion and breakup. The stage of "making" a continent goes back to the Archean, when the first continental masses formed cratons which mostly remained stable ever since. Subsequent collision of weaker continental masses was followed by several extension and compression episodes that resulted in the formation of supercontinents. After the assemblage of Gondwana, a period of predominantly "breaking" , i.e. the breakup of supercontinents, took over. The modern day African continent exhibits different types of margins; continental rifting occurs side by side with recent collision. Since the late 1960's Magnetotelluric (MT) experiments have played an important role in studies of the electrical conductivity structure of Africa. The early results significantly shaped the MT community's understanding of continental scale conductivity belts and basic characteristics of cratons and mobile belts on both crustal and lithospheric mantle scale for some decades. Modern MT studies in Africa have generally supported earlier results with high resistivities observed on cratons and low resistivities observed across mobile belts. Advances in instrumentation, data processing and interpretation resulted in higher resolution images of the lithosphere which in consequence induce an improved understanding of tectonic processes and geological prerequisites for the occurrence of natural resources. The high electrical conductivity of mobile belts and their relation to reactivated fault and detachment zones were often interpreted to characterize mobile belts as tectonic weak zones, which can accommodate stress and constitute zones along which continents can break. Recent breaking of the African continent can be studied on land across the East African rift; however, the lack of amphibian MT experiments across today's margins does not allow for good resolution of remnants of continental break-up processes. Naturally, the regions and the focus of the MT studies in Africa are diverse, but they all contribute to the story of making and breaking a continent.

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Section: Introductionmentioning

confidence: 99%

Making and Breaking of a Continent: Following the Scent of Geodynamic Imprints on the African Continent Using Electromagnetics

Weckmann

2011

Surv Geophys

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“…With the same magnetotelluric method, a similar resistivity of 3 ⍀m at 3 km depth was determined below the San Andrea fault [Unsworth et al, 1997] and a value of 30 ⍀m at 3 km depth was determined at the Kalabsha fault in Upper Egypt [Mekkawi et al, 2005]. Both publications estimate the value of the fracture porosity in the fault zone from the apparent resistivities obtained in the fault zone using Archie's law, with the assumption that the electrical conductivity is the consequence of interconnected pore fluids.…”

Section: Fault Zone Porosity Considerationsmentioning

confidence: 99%

Magnetotelluric study of the Remiremont-Epinal-Rambervillers zone of migrating seismicity, Vosges (France)

Bourlange

Mekkawi

Conin

et al. 2012

Bulletin De La Société Géologique De France

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The magnetotelluric method has been used to image the deep electrical structure of the Remiremont-Epinal-Rambervillers region in the French Vosges Massif, which has presented a significant seismic activity in the past decades. Several earthquakes of moderate magnitude (up to 5.1) occurred in this area with a systematic migration along a nearly N-S direction. Inversion of the magnetotelluric data reveals zones of high electrical conductivity. A large conductive body presents a significative spatial correlation with the region that was most recently affected by earthquakes. This conductive body is interpreted as a consequence of the presence of a fluid filled basement fault network in proximity to the zone affected by the last seismic crisis, where fluid pressure diffusion takes place for several years after the main shock and participates in maintaining a microseismic activity. Etude magnétotellurique des zones de migration de sismicité de Remiremont-Epinal-Rambervillers, Vosges (France)Mots-clés. -Magnétotellurique, Fluides, Réseau de failles, Sismicité, Massif des Vosges.Résumé. -La méthode magnétotellurique a été utilisée pour imager la structure électrique profonde de la région de Remiremont-Epinal-Rambervillers dans les Vosges, où a été enregistrée une importante activité sismique pendant les trois dernières décennies. Plusieurs séismes de magnitude modérée (jusqu'à 5.1) ont eu lieu dans cette région avec une migration systématique des événements sismiques le long d'un axe orienté environ Nord-Sud. L'inversion des données magnétotelluriques révèle plusieurs zones de conductivité électrique élevée. Un corps électriquement conducteur de grande extension présente une corrélation spatiale significative avec la région affectée par les tremblements de terre les plus ré-cents. Ce corps conducteur est interprété comme la signature électrique de la présence d'un réseau de fractures saturé de fluides conducteurs, à proximité de la zone affectée par cette dernière crise sismique, et où la diffusion de la pression de fluide prend place pendant plusieurs années après le choc principal et participe ainsi au maintien d'une activité microsismique.

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“…This earthquake was measured 5.4 on the Richter scale, with its epicentre occurring about 60 km to the south of the High Aswan Dam (Mekkawi et al . ).…”

Section: Introductionmentioning

confidence: 97%

Using resistivity logs to estimate hydraulic conductivity of a Nubian sandstone aquifer in southern Egypt

Khalil

Ramalho

Santos

2011

Near Surface Geophysics

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The present study was carried out in the Khor-El-Ramlah area, in a Nubian sandstone aquifer. It is located in the western bank of Nasser Lake, southern Egypt, in a tectonically active area, which is dissected by many regional faults extending towards the lake. For this reason, the Nubian sandstone aquifer in this area is expected to be recharged by a large amount of seepage water from the lake. One important parameter used to quantify seepage is hydraulic conductivity. Since in this area there is no available information about hydraulic conductivity via pumping tests or laboratory examination of core samples, an attempt is made in this study to estimate hydraulic conductivity using available resistivity logs by applying the Kozeny-Carman model. The clay contamination effect on porosity estimation has been removed via application of the Waxman-Smits model. The hydraulic conductivity is estimated to be 9.5 ± 2.5 m/day for the Nubian sandstone aquifer in this area. The present result is in agreement with the estimated and measured hydraulic conductivity values for the same aquifer in nearby areas and could be used to estimate seepage in this zone. The application of geophysical well logging often provides a cost-effective and efficient alternative to estimate aquifer parameters.out. Therefore, no information about hydraulic conductivity or seepage water quantity is known for that area. In particular, the seepage quantity is expected to be higher than in other parts around the lake due to the local dense fault system.The main objective of the present study is to estimate the hydraulic conductivity of the Nubian sandstone aquifer for this area, from the measured resistivity logs of well RML, in order to make it available for any future estimation of seepage. GEOLOGICAL SETTINGThe Arabo-Nubian granitic massif is bisected by the Red Sea rift and it is the continuation of the Gulfs of Suez and Aqaba, occupying 10% of Egypt's surface. Recent tectonic structures, which represent the most active regions of the Precambrian shield outcrop in the eastern part of Egypt and Sinai.Many researchers have studied the Nubian section in the Aswan area, which lies just north of the basement trough. Shawa and Issawi (1978), Van Houten et al. (1984) and Yan et al. (2003) divided the Nubian formation into three members from bottom to top: the Tarf, Qusier and Shab members. The Tarf member overlies the Precambrian basement and is composed of yellowish and white coloured sandstone, shale and pebbly sandstone. The sandstone is well cemented and has a grain size ranging from fine to coarse. This is unconformably overlain by the Qusier member,

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Electrical structure of the tectonically active Kalabsha Fault, Aswan, Egypt

Cited by 15 publications

References 26 publications

Making and Breaking of a Continent: Following the Scent of Geodynamic Imprints on the African Continent Using Electromagnetics

Making and Breaking of a Continent: Following the Scent of Geodynamic Imprints on the African Continent Using Electromagnetics

Magnetotelluric study of the Remiremont-Epinal-Rambervillers zone of migrating seismicity, Vosges (France)

Using resistivity logs to estimate hydraulic conductivity of a Nubian sandstone aquifer in southern Egypt

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