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Radwan, Ali M.
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Radwan, Ali M.
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- PublicationOpen AccessEvaluation of near-surface groundwater aquifers through integrated geophysical and geodetic measurementsExtensive geophysical and geodetic measurements were carried out to evaluate the groundwater aquifer, trace the basement relief, as well as detect the igneous intrusions and structural elements (mainly faults) that affect the occurrence of groundwater in the study area. The fieldwork included resistivity sounding, a geomagnetic survey, and Global Positioning System measurements. The magnetic results showed the presence of a group of main faults in East-west trend at the western part of the area and major fault at the northern part of the area of NW-SW trend. The findings also showed the presence of two igneous rock intrusions located in the middle of the eastern part of the valley. Pronounced differences in the depths of basement rocks have been identified, ranging between 0 and 900 m from the surface. Both high horizontal movements and high shear strain rates have been found to be concentrated at the southeast of the study area and it was noted that high stress was accumulated along the main observed faults and at the main groundwater aquifers. The geoelectrical results confirmed the presence of two aquifers; a shallow aquifer (Quaternary aquifer) that narrows northwards and a Nubian sandstone aquifer, which considered the main aquifer. The Nubian sandstone aquifer carries groundwater in the region, which overlies the last geoelectric unit represented by the basement complex layer and geological structures affecting the potential availability of groundwater in the study area, as proved by the geomagnetic survey and stress accumulation.
59 10 - PublicationOpen AccessSeismic and Geodetic Crustal Moment-Rates Comparison: New Insights on the Seismic Hazard of Egypt(2021-08-25)
; ; ; ; ; ; ; ;; ; ;A comparative analysis of geodetic versus seismic moment-rate estimations makes it possible to distinguish between seismic and aseismic deformation, define the style of deformation, and also to reveal potential seismic gaps. This analysis has been performed for Egypt where the present-day tectonics and seismicity result from the long-lasting interaction between the Nubian, Eurasian, and Arabian plates. The data used comprises all available geological and tectonic information, an updated Poissonian earthquake catalog (2200 B.C.–2020 A.D.) including historical and instrumental datasets, a focal-mechanism solutions catalog (1951–2019), and crustal geodetic strains from Global Navigation Satellite System (GNSS) data. The studied region was divided into ten (EG-01 to EG-10) crustal seismic sources based mainly on seismicity, focal mechanisms, and geodetic strain characteristics. The delimited seismic sources cover the Gulf of Aqaba–Dead Sea Transform Fault system, the Gulf of Suez–Red Sea Rift, besides some potential seismic active regions along the Nile River and its delta. For each seismic source, the estimation of seismic and geodetic moment-rates has been performed. Although the obtained results cannot be considered to be definitive, among the delimited sources, four of them (EG-05, EG-06, EG-08, and EG-10) are characterized by low seismic-geodetic moment-rate ratios (<20%), reflecting a prevailing aseismic behavior. Intermediate moment-rate ratios (from 20% to 60%) have been obtained in four additional zones (EG-01, EG-04, EG-07, and EG-09), evidencing how the seismicity accounts for a minor to a moderate fraction of the total deformational budget. In the other two sources (EG-02 and EG-03), high seismic-geodetic moment-rates ratios (>60%) have been observed, reflecting a fully seismic deformation193 61 - PublicationOpen AccessThe Kamil Crater in Egypt(2010-08-13)
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ;Folco, L.; Museo Nazionale dell'Antartide Università di Siena, Via Laterina 8, 53100, Siena, Italy. ;Di Martino, M.; Istituto Nazionale di Astrofisica, Osservatorio Astronomico di Torino, 10025 Pino Torinese, Italy. ;El Barkooky, A.; Department of Geology, Faculty of Sciences, Cairo University, Giza, Egypt. ;D'Orazio, M.; Dipartimento di Scienze della Terra, Università di Pisa, Via S. Maria 53, 56126 Pisa, Italy. ;Lethy, A.; National Research Institute of Astronomy and Geophysics, Helwan, Egypt. ;Urbini, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Nicolosi, I.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Hafez, M.; National Research Institute of Astronomy and Geophysics, Helwan, Egypt. ;Cordier, C.; Museo Nazionale dell'Antartide Università di Siena, Via Laterina 8, 53100, Siena, Italy. ;van Ginneken, M.; Museo Nazionale dell'Antartide Università di Siena, Via Laterina 8, 53100, Siena, Italy. ;Zeoli, A.; Museo Nazionale dell'Antartide Università di Siena, Via Laterina 8, 53100, Siena, Italy. ;Radwan, A. M.; National Research Institute of Astronomy and Geophysics, Helwan, Egypt. ;El Khrepy, S.; National Research Institute of Astronomy and Geophysics, Helwan, Egypt. ;El Gabry, M.; National Research Institute of Astronomy and Geophysics, Helwan, Egypt. ;Gomaa, M.; National Research Institute of Astronomy and Geophysics, Helwan, Egypt. ;Barakat, A. A.; Egyptian Mineral Resources Authority, 3 Salah Salem Road, Abassiya, Cairo, Egypt. ;Serra, R.; Dipartimento di Fisica, Università di Bologna, Via Irnerio 46, 40126 Bologna, Italy. ;El Sharkawi, M.; Department of Geology, Faculty of Sciences, Cairo University, Giza, Egypt.; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; We report on the discovery in southern Egypt of an impact crater 45 m in diameter with a pristine rayed structure. Such pristine structures have been previously observed only on atmosphereless rocky or icy planetary bodies in the Solar System. This feature and the association with an iron meteorite impactor and shock metamorphism provides a unique picture of small-scale hypervelocity impacts on the Earth's crust. Contrary to current geophysical models, ground data indicate that iron meteorites with masses of the order of tens of tons can penetrate the atmosphere without significant fragmentation.230 519 - PublicationOpen AccessCrustal Strain and Stress Fields in Egypt from Geodetic and Seismological Data(2021-04-05)
; ; ; ; ; ; ; ; ;; ;The comparison between crustal stress and surface strain azimuthal patterns has provided new insights into several complex tectonic settings worldwide. Here, we performed such a comparison for Egypt taking into account updated datasets of seismological and geodetic observations. In north-eastern Egypt, the stress field shows a fan-shaped azimuthal pattern with a WNW–ESE orientation on the Cairo region, which progressively rotated to NW–SE along the Gulf of Aqaba. The stress field shows a prevailing normal faulting regime, however, along the Sinai/Arabia plate boundary it coexists with a strike–slip faulting one (σ1 ≅ σ2 > σ3), while on the Gulf of Suez, it is characterized by crustal extension occurring on near-orthogonal directions (σ1 > σ2 ≅ σ3). On the Nile Delta, the maximum horizontal stress (SHmax) pattern shows scattered orientations, while on the Aswan region, it has a WNW–ESE strike with pure strike–slip features. The strain-rate field shows the largest values along the Red Sea and the Sinai/Arabia plate boundary. Crustal stretching (up to 40 nanostrain/yr) occurs on these areas with WSW–ENE and NE–SW orientations, while crustal contraction occurs on northern Nile Delta (10 nanostrain/yr) and offshore (~35 nanostrain/yr) with E–W and N–S orientations, respectively. The comparison between stress and strain orientations over the investigated area reveals that both patterns are near-parallel and driven by the same large-scale tectonic processes.213 15 - PublicationRestrictedKamil Crater (Egypt): Ground truth for small-scale meteorite impacts on Earth(2011-02)
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ;Folco, L.; Museo Nazionale dell’Antartide Università di Siena, Via Laterina 8, 53100 Siena, Italy ;Di Martino, M.; Istituto Nazionale di Astrofi sica, Osservatorio Astronomico di Torino, 10025 Pino Torinese, Italy ;El Barkooky, A.; Department of Geology, Faculty of Sciences, Cairo University, Giza, Egypt ;D’Orazio, M.; Dipartimento di Scienze della Terra, Università di Pisa, Via S. Maria 53, 56126 Pisa, Italy ;Lethy, A.; National Research Institute of Astronomy and Geophysics, Helwan, Egypt ;Urbini, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Nicolosi, I.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Hafez, M.; National Research Institute of Astronomy and Geophysics, Helwan, Egypt ;Cordier, C.; Museo Nazionale dell’Antartide Università di Siena, Via Laterina 8, 53100 Siena, Italy ;van Ginneken, M.; Museo Nazionale dell’Antartide Università di Siena, Via Laterina 8, 53100 Siena, Italy ;Zeoli, A.; Museo Nazionale dell’Antartide Università di Siena, Via Laterina 8, 53100 Siena, Italy ;Radwan, A. M.; National Research Institute of Astronomy and Geophysics, Helwan, Egypt ;El Khrepy, S.; National Research Institute of Astronomy and Geophysics, Helwan, Egypt ;El Gabry, M.; National Research Institute of Astronomy and Geophysics, Helwan, Egypt ;Gomaa, M.; National Research Institute of Astronomy and Geophysics, Helwan, Egypt ;Barakat, A. A.; Egyptian Mineral Resources Authority, 3 Salah Salem Road, Abassiya, Cairo, Egypt ;Serra, R.; Egyptian Mineral Resources Authority, 3 Salah Salem Road, Abassiya, Cairo, Egypt ;El Sharkawi, M.; Department of Geology, Faculty of Sciences, Cairo University, Giza, Egypt; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; Small impact craters (<300 m in diameter) are rare on Earth and mostly deeply eroded, so that knowledge of their formation mechanism and the hazard small impactors constitute to human populations is largely based on physical models. We report on the geophysical investigation of the Kamil Crater we recently discovered in southern Egypt. The Kamil Crater is a <5 k.y. old impact crater 45 m in diameter, with a pristine ejecta ray structure. Such well-preserved structures have been previously observed only on extraterrestrial rocky or icy planetary bodies. This crater feature, and the association with an iron meteorite impactor and shock metamorphism, provides a unique impression of aspects of small-scale hypervelocity impacts on the Earth’s crust. Contrary to current models, ground data indicate that iron meteorites with masses of tens of tons may be able to penetrate the atmosphere without substantial fragmentation.313 33 - PublicationRestrictedGeological and geophysical investigation of Kamil crater, Egypt(2012-12-14)
; ; ; ; ; ; ; ; ; ; ; ; ; ; ;Urbini, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Nicolosi, I.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Zeoli, A.; Museo Nazionale dell’Antartide Universita` di Siena, Via Laterina 8, 53100 Siena, Italy ;El Khrepy, S.; National Research Institute of Astronomy and Geophysics, Helwan, Egypt ;Lethy, A.; National Research Institute of Astronomy and Geophysics, Helwan, Egypt ;Hafez, M.; National Research Institute of Astronomy and Geophysics, Helwan, Egypt ;El Gabry, M.; National Research Institute of Astronomy and Geophysics, Helwan, Egypt ;El Barkooky, A.; Department of Geology, Faculty of Sciences, Cairo University, Giza, Egypt ;Barakat, A.; Egyptian Mineral Resources Authority, 3 Salah Salem Road, Abassiya, Cairo, Egypt ;Gomaa, M.; Museo Nazionale dell’Antartide Universita` di Siena, Via Laterina 8, 53100 Siena, Italy ;Radwan, A. M.; Museo Nazionale dell’Antartide Universita` di Siena, Via Laterina 8, 53100 Siena, Italy ;El Sharkawi, M.; Department of Geology, Faculty of Sciences, Cairo University, Giza, Egypt ;D’Orazio, M.; Dipartimento di Scienze della Terra, Universita` di Pisa, Via S. Maria 53, 56126 Pisa, Italy ;Folco, L.; Dipartimento di Scienze della Terra, Universita` di Pisa, Via S. Maria 53, 56126 Pisa, Italy; ; ; ; ; ; ; ; ; ; ; ; ; We detail the Kamil crater (Egypt) structure and refine the impact scenario, based on the geological and geophysical data collected during our first expedition in February 2010. Kamil Crater is a model for terrestrial small-scale hypervelocity impact craters. It is an exceptionally well-preserved, simple crater with a diameter of 45 m, depth of 10 m, and rayed pattern of bright ejecta. It occurs in a simple geological context: flat, rocky desert surface, and target rocks comprising subhorizontally layered sandstones. The high depth-to-diameter ratio of the transient crater, its concave, yet asymmetric, bottom, and the fact that Kamil Crater is not part of a crater field confirm that it formed by the impact of a single iron mass (or a tight cluster of fragments) that fragmented upon hypervelocity impact with the ground. The circular crater shape and asymmetries in ejecta and shrapnel distributions coherently indicate a direction of incidence from the NW and an impact angle of approximately 30 to 45 . Newly identified asymmetries, including the off-center bottom of the transient crater floor downrange, maximum overturning of target rocks along the impact direction, and lower crater rim elevation downrange, may be diagnostic of oblique impacts in well-preserved craters. Geomagnetic data reveal no buried individual impactor masses >100 kg and suggest that the total mass of the buried shrapnel >100 g is approximately 1050–1700 kg. Based on this mass value plus that of shrapnel >10 g identified earlier on the surface during systematic search, the new estimate of the minimum projectile mass is approximately 5 t.479 69