Analysis and interpretation of gravity data from the Aluto-Langano geothermal field of Ethiopia     

Hakim Saibi  Essam Aboud  Sachio Ehara 《Acta Geophysica》2012,60(2):318-336

The Aluto-Langano geothermal field is located in the central southern portion of Ethiopia within the Ethiopian Rift Valley. The gravity of the area was surveyed in an attempt to delineate the subsurface structure and to better understand the relationship between the geothermal systems and the subsurface structure. The gravity data were analyzed using integrated gradient interpretation techniques, such as the Horizontal Gradient (HG), Source Edge Detection (SED), and Euler Deconvolution (ED) methods. These techniques detected many faults that were compared with the mapped faults in the surface geology. The results of the present study will lead to an improved understanding of the geothermal system in the study area and aid the future geothermal exploration of the area.  相似文献   

Gravity and magnetotelluric investigations to elicit the origin of Hammam Faraun hot spring,Sinai Peninsula,Egypt   总被引：1，自引：0，他引：1  

Mohamed Abdelzaher  Jun Nishijima  Gad El-Qady  Essam Aboud  Osama Masoud  Mamdoh Soliman  Sachio Ehara 《Acta Geophysica》2011,59(3):633-656

There is a clear correlation between the principal areas of current geothermal development and the seismically active boundaries of the moving segments of lithosphere defined by the plate tectonic models of the Earth. The tectonic position of Egypt in the northeastern corner of African continent suggests that the most important areas for geothermal exploration are in the region where a cluster of hot springs with varied temperatures was located around the Gulf of Suez. Gravity and magnetotelluric surveys were made in the area of Hammam Faraun hot spring, which represents the most promising area for geothermal development in Egypt. These surveys were carried out for the purpose of eliciting the origin of Hammam Faraun hot spring. The results of the analyses and interpretations of these data show that the heat source of the hot spring is due to uplift of hot basement rock. This uplift may cause deep circulation and heating of the undergroundwater.  相似文献   

Active tectonic trends and crustal modeling of the eastern Mediterranean Sea deduced from geophysical data     

El Sayed Selim  Essam Abouad  Sayed S. R. Moustafa  Nassir S. Al-Arifi 《Environmental Earth Sciences》2016,75(12):1036

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GPS-GRAVIMETRIC GEOID DETERMINATION IN EGYPT     

Essam Ghanem 《地球空间信息科学学报》2001,4(1):19-23

1　ＩｎｔｒｏｄｕｃｔｉｏｎＤｉｆｆｅｒｅｎｔｇｅｏｉｄｓｏｌｕｔｉｏｎｓｗｅｒｅｃａｒｒｉｅｄｏｕｔｆｏｒＥ ｇｙｐｔｕｓｉｎｇｈｅｔｅｒｏｇｅｎｅｏｕｓｄａｔａａｎｄｄｉｆｆｅｒｅｎｔｍｅｔｈｏｄｏｌｏｇｉｅｓ (Ｅｌ＿Ｔｏｋｈｅｙ ,1 993) .ＴｈｅｍａｉｎｇｏａｌｏｆｔｈｉｓｐａｐｅｒｉｓｔｏｄｅｔｅｒｍｉｎｅａｍｏｓｔａｃｃｕｒａｔｅｎｅｗｇｅｏｉｄｆｏｒＥｇｙｐｔｔａｋｉｎｇａｄｖａｎｔａｇｅｏｆａｎｅｗｕｐｄａｔｅｄｇｒａｖｉｔｙｄａｔａｂａｓｅ,ｔｈｅｉｎｆｏｒｍａｔｉｏｎｇｉｖｅｎｂｙ…  相似文献   

Discovery of the largest impact crater field on Earth in the Gilf Kebir region, Egypt     

Philippe Paillou  Ahmed El Barkooky  Aly Barakat  Jean-Marie Malezieux  Bruno Reynard  Jean Dejax  Essam Heggy 《Comptes Rendus Geoscience》2004,336(16):1491-1500

Using orbital imaging radar, we have detected a large number of circular structures in the southwestern Egyptian desert, covering more than 4500 km² close to the Gilf Kebir plateau in sandstones of Upper Cretaceous. Fieldwork confirmed that it is a new impact crater field: 13 craters from 20 m to 1 km in diameter were studied. The impact origin is confirmed by the observation of shock-related structures, such as shatter cones and planar fractures in quartz grains of breccia. Considering the extension of the crater field, it was possibly created by several meteorites that broke up when entering the atmosphere. To cite this article: P. Paillou et al., C. R. Geoscience 336 (2004).

Résumé

À partir d'images satellites issues de systèmes radar, nous avons détecté un grand nombre de structures circulaires dans le Sud-Ouest du désert égyptien, s'étendant sur plus de 4500 km² à l'est du plateau du Gilf Kebir, dans des grès du Crétacé supérieur. Une étude sur le terrain a permis de vérifier qu'il s'agit d'un champ d'impacts météoritiques jusque là inconnu : 13 structures, d'un diamètre compris entre 20 m et 1 km, ont été reconnues comme cratères d'impact. La présence d'un grand nombre de cônes de percussion et de brèches dans lesquelles des quartz choqués à structures planaires ont été observés confirment l'hypothèse de l'impact. Considérant l'extension du champ d'impact, il a probablement été créé par plusieurs météorites qui se sont fragmentées dans l'atmosphère terrestre. Pour citer cet article : P. Paillou et al., C. R. Geoscience 336 (2004).  相似文献   

A local geoid determination based on ellipsoid approximation in Western China     

Essam Ghanem 《地球空间信息科学学报》2002,5(3):6-10

A new methodology for precise geoid determination with finest local details based on ellipsoidal approximation is presented.This methodology is formulated through the “fixed-free two-boundary value problem“ based on the observable of the type modulus of gravity intensity,gravity acceleration and gravity potential at the GPS positioned stations,with support of the known geoid‘s potential value,W0.  相似文献   

A simplified seismic analysis of rigid base liquid storage tanks under vertical exicitation with soil-structure interaction     

Medhat A. Haroun  Essam A. Abdel-Hafiz 《Soil Dynamics and Earthquake Engineering》1986,5(4):217-225

A study is carried out to evaluate dynamic response of an elastic circular cylindrical tank having a rigid base under a vertical excitation taking into consideration the interaction with the foundation soil. At first, the soil is represented by frequency-independent parameters. Two coupled differential equations, governing the motion of the shell and the base, are solved using a step by step integration technique. The hydrodynamic pressures, acting on the shell and on the base, are derived from a velocity potential function which satisfies the Laplace equation and the appropriate boundary conditions. The response of the simplified model of a tank having a rigid base on a stiff foundation soil is compated to that obtained elsewhere to check the accuracy of the present model. Reasonable agreement is found between the maximum wall displacement and the associated stresses with those found by a more elaborate model. The interaction of the tank and the soil reduces the response than that calculated under the assumption of a rigid foundation soil. A parametric study to examine the effects of the height-to-radius ratio of the tank, and the effects of the shear wave velocity of the soil on the response is conducted. Varieties of foundation models are used to assess the sensitivity of the response to the variation in the soil parameters. Finally, a more representative solution for the problem in the frequency domain is obtained where the soil is appropriately modelled by frequency-dependent parameters. The transfer functions of the response of the tank wall and of the relative base motion are evaluated, and a comparison between the frequency-dependent and the frequency-independent solutions is made.  相似文献   

Physical properties of three short period close binaries:KIC 2715417,KIC 6050116 and KIC 6287172     

Mahmoud AbdelFattah NegmEldin  Ahmed Essam Elsayed  Shahinaz Mostafa Yousef 《天文和天体物理学研究(英文版)》2019,(2)

We present the physical parameters of three short period close binaries using data observed from the Kepler Space Telescope. All of these observations were taken in a single bandpass(which approximates the Johnson V-band). Our three systems are KIC 2715417, KIC 6050116 and KIC 6287172. The first system, KIC 2715417, is considered a semi-detached system with the secondary component filling its Roche lobe. The second system, KIC 6050116, is an overcontact system, while the third system, KIC 6287172, belongs to ellipsoidal variables as deduced from the Roche lobe geometry. For photometric analysis, we used the PHOEBE software package, which is based on the Wilson-Devinney code. Due to lack of spectroscopic data, the photometric mass ratios are determined from the analyses of light curves using the q-search method. The absolute parameters are determined using three different methods(Harmanec, Maceroni Van'tVeer and Gazeas Niarchos).  相似文献   

Bacterial community and some physico-chemical characteristics in a subtropical mangrove environment in Bahrain   总被引：5，自引：0，他引：5  

Al-Sayed HA  Ghanem EH  Saleh KM 《Marine pollution bulletin》2005,50(2):147-155

A study of bacterial communities and some physico-chemical parameters of a subtropical mangrove habitat in the Arabian Gulf (Bahrain) was carried out in 1993-1994. Six stations at different parts of the tidal channel were selected for sampling. The mangrove habitat was found to harbor diverse bacterial communities, included among them anoxygenic phototrophs (AP), oxygenic phototrophs (OP), organotrophs (OT), total coliforms (TC), faecal coliforms (FC) and haloalkaliphiles (HA). Spatial and temporal variations in bacterial communities and environmental parameters were found. Each of the OT, AP, TC, and FC were dominant in the innermost stations (S1&S2) and gradually decreased seaward. The HA community on the other hand, was dominant at the seaward stations (S5&S6) and was most likely to have originated from the sea through the tidal flows. Both AP and OT were considered as part of the mangrove native flora, whereas TC and FC were alien and believed to have been introduced through partially treated sewage released at the upstream of the tidal channel. Closely monitoring of the mangrove water revealed succession pattern in bacterial communities. The AP community was predominant from November 1993 to March 1994, succeeded by dominance of OP from June 1994 to October 1994. Both bacterial blooms gave water a pinkish, purple, or green color, respectively. Although OT prevailed during Transitional period between AP and OP eutrophication, it remained comparatively constant (not less than 2 x 10(5)cfu/ml) through other periods. Frequent eutrophication phenomena of OP, which took place in summer and autumn, coincided with increases in water temperature, chlorophyll a, and nutrients (NO(3)(-) and PO(4)(-)). On the other hand, OT and AP were negatively correlated with temperature, salinity and chlorophyll a, but no specific pattern was observed in relation to NO(3)(-) and PO(4)(-). In comparison with seawater, nutrients such as NO(3)(-) and PO(4)(-) were consistently higher in the mangrove habitat. Partially treated sewage and farm drainage canals are proposed to form additional sources of nutrients. Although, the mangrove habitat has been demonstrated to possess self-cleaning properties, data obtained suggest that anthropogenic pollution has a deleterious effect.  相似文献   

Contribution of gravity and magnetic data in delineating the subsurface structure of Hammam Faroun area, Gulf of Suez, Egypt     

Essam Aboud  El Sayed Selim  Ahmed El Bishlawy 《Arabian Journal of Geosciences》2011,4(1-2):249-257

The Hammam Faroun has a particular importance due to its geothermal activity which constitutes the main geothermal resource of Egypt. The area is located on the Sinai Peninsula, a subplate bounded by two seismically active structural zones along the Gulf of Suez and Gulf of Aqaba. High-resolution ground-based gravity and magnetic data are available for the entire Hammam Faroun area, acquired as part of a national project to explore for mineral, geothermal, and hydrocarbon resources. Gravity and magnetic data were analyzed using Source Edge Detection and Source Parameter Imaging (SPI) techniques to image subsurface structures. These analyses show that the area is characterized by a set of northwest-striking faults lying parallel to the Gulf of Suez. Orthogonal patterns are also present, possibly related to rifting of the Gulf of Suez. Depth analysis using the SPI method indicates that surface faults extend to 5-km depth. Analysis of potential-field data elucidates the structurally complex subsurface structure of the Hammam Faroun area.  相似文献