Abstract
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).
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Acknowledgments
We thank all the colleagues who worked on the field under difficult conditions to provide the observations. Also, we thank the Seismological Center staff in Aswan, Egypt, for all support provided during acquisition of the data.
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Radwan, A.M., Hosny, A., Kotb, A. et al. Assessment of the geodynamical settings around the main active faults at Aswan area, Egypt. Arab J Geosci 8, 4317–4327 (2015). https://doi.org/10.1007/s12517-014-1504-x
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DOI: https://doi.org/10.1007/s12517-014-1504-x