National Research Institute for Astronomy and Geophysics NRIAG

Ḩalwān, Egypt

National Research Institute for Astronomy and Geophysics NRIAG

Ḩalwān, Egypt

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Rayan A.,National Research Institute for Astronomy and Geophysics NRIAG | Fernandes R.M.S.,UBI | Fernandes R.M.S.,Technical University of Delft | Khalil H.A.,National Research Institute for Astronomy and Geophysics NRIAG | And 3 more authors.
Journal of Geodynamics | Year: 2010

The proper evaluation of crustal deformations in the Aswan (Egypt) region is crucial due to the existence of one major artificial structure: the Aswan High Dam. This construction induced the creation of one of the major artificial lakes: Lake Nasser, which has a surface area of about 5200 km2 with a maximum capacity of 165 km3. The lake is nearly 550 km long (more than 350 km within Egypt and the remainder in Sudan) and 35 km across at its widest point. Great attention has focused on this area after the November 14, 1981 earthquake (ML = 5.7), with its epicenter southwest of the High Dam. In order to evaluate the present-day kinematics of the region, its relationship with increasing seismicity, and the possible influence of the Aswan High Dam operation, a network of 11 GPS sites was deployed in the area. This network has been reobserved every year since 2000 in campaign style. We present here the results of the analysis of the GPS campaign time-series. These time-series are already long enough to derive robust solutions for the motions of these stations. The computed trends are analyzed within the framework of the geophysical and geological settings of this region. We show that the observed displacements are significant, pointing to a coherent intraplate extensional deformation pattern, where some of the major faults (e.g., dextral strike-slip Kalabsha fault and normal Dabud fault) correspond to gradients of the surface deformation field. We also discuss the possible influence of the water load on the long-term deformation pattern. © 2009 Elsevier Ltd. All rights reserved.


Radwan A.M.,National Research Institute for Astronomy and Geophysics NRIAG | Hosny A.,National Research Institute for Astronomy and Geophysics NRIAG | Kotb A.,National Research Institute for Astronomy and Geophysics NRIAG | Khalil A.,National Research Institute for Astronomy and Geophysics NRIAG | And 3 more authors.
Arabian Journal of Geosciences | Year: 2015

The proper evaluation of the level of crustal deformations in the Aswan region, especially around the main active faults, is crucial due to the existence of one major artificial structure: the Aswan High Dam. This construction created one of the major artificial lakes in the world: Lake Nasser. The Aswan area is considered as an active seismic area in Egypt due to the frequent recurrence of felted earthquakes. Two earthquakes occurred in the region (Kalabsha fault) after the construction of the Aswan High Dam: November 14, 1981 (ML = 5.6) and December 26, 2011 (ML = 4.1). The main goal of this study is to evaluate the active geological structures that can potentially affect the Aswan High Dam and that are being monitored in detail. For implementing such objective, several techniques (namely magnetic, seismic and GPS) have been utilized. A detailed land magnetic survey was carried out for the total component of the geomagnetic field using two proton magnetometers. The obtained magnetic results reveal that there are three major parallel faults affecting the area. The most dominant magnetic trend strikes those faults in the WNW-ESE direction. The seismicity and the fault plane solution associated with the December 26, 2011 earthquake have been also analyzed. The source mechanism of this event delineates two nodal planes. The trending ENE-WSW to E-W is consistent with the direction of the Kalabsha fault and its extension towards east. The trending NNW-SSE to N-S is consistent with the N-S fault trending. The movement along the ENE-WSW plane is right lateral, while left lateral along the NNW-SSE plane. Based on the estimated relative motions using GPS, dextral strike-slip motions at the Kalabsha and Seiyal fault systems are identified by the velocity gradient changes between the southern and northern stations. However, at the area between Kalabsha and Seiyal faults, other relative movements are also observed, which is consistent with other set of faults (N-S). © 2014, Saudi Society for Geosciences.

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