Kamal Abdelrahman

Milk composition of Majaheim, Wadah and Hamra camels in Saudi Arabia

Abstract The chemical composition and nitrogen distribution of camel milk from three ecotype (Majaheim, Wadah and Hamra) camels, in the central region of Saudi Arabia, were studied. The average results for pH, and percentage acidity, total solids, fat, protein, lactose and ash for Majaheim were 6.63, 0.144, 11.35, 3.22, 2·91, 4·43 and 0·79, for Wadah they were 6·65, 0·14, 10·07, 2·46, 2·36, 4·44 and 0·81, and for Hamra they were 6·65, 0·137, 10·63, 2·85, 2·52, 4·46 and 0·80, respectively. The mean values (mg/100 ml) for nonprotein N (NPN), protein N, casein N and whey protein N for Majaheim were 44·6, 411, 300 and 112; for Wadah they were 38·1, 331, 244 and 87·6 and for Hamra they were 40·4, 354, 255 and 99·4, respectively. With respect to mineral contents, the levels of Ca, Mg, P, Na and K of Majaheim, Wadah and Hamra camel milks were 120, 109 and 119, 13·0,12·4, and 11·6; 88·6, 83·5 and 90·1; 65·0, 73·4 and 64·6, and 135, 172 and 124 mg/100 g, respectively. However, the contents of Cu, Fe, Mn and Zn of Majaheim, Wadah and Hamra camel milk were similar, with some individual variations.

Structure of the Yanbu suture zone in Northwest Saudi Arabia inferred from aeromagnetic and seismological data

The present work focuses on a study of the Yanbu suture zone and related ophiolites using aeromagnetic and seismological data. The interpretation of aeromagnetic data indicates that NW–SE- and NE–SW-trending structural faults dominate the study area. These faults coincide with narrow and elongated magnetic highs, possibly caused by intrusions emplaced along the faults. The NE trend is dissected by cross-cutting NW-trending faults in some places. The NE-oriented suture zone is marked by short-wavelength high magnetic anomalies associated with ultramafic rocks (ophiolites) and is divided by the NW-oriented left-lateral Najid faulting (Qazaz shear zone) into two shifted alignments. This implies that deep-seated regional trends govern to a large extent the location and extension of the ophiolite exposures. There is a clear correlation between land earthquakes and the interpreted magnetic structures, where the majority of earthquake epicenters lie on or close to the interpreted major faults. A clear concentration of earthquakes is observed where the NE-trending faults cross the Red Sea NNW-trending faults. Here, two separate aftershock clusters occur to the north of Yanbu City, indicating the reactivation of the pre-existing Precambrian NE-trending transform fault,which crosses two parallel NNW-trending faults that have been injected by Cenozoic volcanics during the Cenozoic rifting of the Red Sea. These results indicate that the seismotectonics of the study area is strongly related to the geodynamic rifting processes acting in the Red Sea, where the relative movement between African and Arabian plates resulted in several series of normal and transform faults that run parallel and cross the Red Sea, respectively.

Seismicity and Seismotectonics of Jeddah-Makkah Region, West-Central Saudi Arabia

Jeddah-Makkah regionis have been suffering from earthquake crisis where some moderate to destructive earthquakes have been recorded. These earthquake activities are oriented along major faults or clustered in certain spots. Moreover, these earthquake events have annual recurrence periods, so the identification of these seismogenic source zones is of utmost importance for mapping the most hazardous localities which should be avoided in the future urban planning. Historical and instrumental earthquakes have been collected from national and international data centers and unified in catalogue. The existence of microearthquakes inland suggests that there is a significant level of tectonic activity at away from the axial trough of the Red Sea. Then, seismogenic source zones have been defined depending on the major tectonic trends; distribution of earthquake epicenters, seismicity rate (a & b-values) and fault plane solution of major earthquakes. It is concluded that Jeddah-Makkah region is affected by the outlined five seismogenic source zones; three of these zones aligned of the main Red Sea axial trough (southwestern Jeddah, western Jeddah, and northwestern Jeddah zones), while the other two zones are located in the land area of the region (Thewal-Rabegh and Jeddah-Makkah zones). These inland zones correlated well with the main trends of major tectonics which refleet the reactivation of tectonic movements along these fault trends. The Red Sea zones are in agreement with the main path of the axial trough. The range of b-value in these identified zones is 0.65 to 1.03 through these identified zones. The area characterized by higher b-values could be indicative of a relative low stress regime which was a result of resulting from the stress release by the earthquakes. Whereas, the areas of lower b-values can be considered as an evidence of a relatively higher stress regime associated with a dominantly extensional stresses. Based on aforementioned, the region is suffering from different stress level accumulations which, in turn, cause earthquakes with different magnitudes. Accordingly, deployment of local seismograph network through Jeddah-Makkah region is highly recommended. These results will support, to a great extent, seismic hazard assessment and risk mitigation of the region.

Geotechnical investigation of the El-Elb dam site, northwest Riyadh, Saudi Arabia, using 2D resistivity and ground-penetrating radar techniques

In the present study, the existence of cavities, voids, and fractures was verified at the site of the El-Elb Dam, which is located to the northwest of Riyadh City across Wadi Hanifa, using 2D electrical resistivity tomography (ERT) and ground-penetrating radar (GPR) techniques. For this purpose, four ERT profiles were measured on the downstream side of the El-Elb Dam using the Syscal Pro Switch-72 resistivity meter. In addition, a GPR survey using a 400-MHz antenna and a SIR-3000 instrument was conducted along five profiles above the stilling basins on the downstream side of the dam and one radar profile was measured outside the stilling basins area across the course of the wadi. The resultant geophysical data were interpreted with the aid of information from a field-based structural and stratigraphic evaluation of the outcropped bedrock on the banks of the wadi course. The analysis of the inverted ERT and filtered radar sections revealed several resistivity and electromagnetic reflection anomalies that are identified laterally and vertically across the measured sections. These anomalies indicate the presence of fractures and karst features affected the limestone bedrock in the dam site. These near-surface karstified and fractured strata represent a critical hazard to the structural safety of the dam.

Surface Soil Assessment in the Ubhur Area, North of Jeddah, Western Saudi Arabia, Using a Multichannel Analysis of Surface Waves Method

Ten boreholes drilled in Ubhur area up to the depth of bedrock indicted the shallow depth of bedrock where the average depth ranges between 10 and 15 m. The standard penetration test N-values of these boreholes were measured and averaged. Based on N-values to the depth of bedrock, Ubhur area can be classified as site class C and D. Multichannel analysis of surface waves technique has been applied along seventy six profiles using 24-channel geophone array and 4.5Hz vertical geophones with 1m geophone spacing and sledgehammer and/or weight drop as seismic energy sources. Values of shear wave velocity to 30 m are calculated and then averaged (Vs30) where it ranges between 310.08 m/s and 1139.8 m/s. Therefore, Ubhur area can be classified into site class B, C and D based on site classification of the national earthquake hazards reduction program (NEHRP) recommendations. Accordingly, the greatest part of the study area falls in site class C while class B and D covered limited areas in the western and the eastern parts respectively. Depending on the shallow depth of bedrock in the study area, the Vs30 parameter is not applicable in the study area so the average values of Vs for the soil thickness, excluding the bedrock, have been calculated and mapped for site class C and D only. So Vs30 approach is not applicable for areas with shallow depth of bedrock which gives higher classification.

Seismic risk assessment at the proposed site of Gemsa wind power station, southwestern coast of Gulf of Suez, Egypt

Gemsa has been chosen as the site for one of a new generation of power stations along the south-western margin of the Gulf of Suez. This site has been affected by a number of destructive earthquakes (Mw> 5), in addition to large number of earthquakes with magnitudes of less than 5. In this study seismic activities in the region were collected and re-evaluated, and the main earthquake prone zones were identified. It is indicated that this site is affected by the southern Gulf of Suez, northern Red Sea and Gulf of Aqaba source zones. The southern Gulf of Suez source zone is the nearest to the proposed site. The stochastic simulation method has been applied to estimate the Peak GroundAcceleration at the site of the proposed Gemsa power plant. It was noticed that the pseudo-spectral acceleration (PSA) reaches 175 cm/sec2 resulting from the southern Gulf of Suez seismic source. In addition, the response spectrum was conducted with a damping value of 5% of the critical damping, and the predominant period reached 0.1sec at the site. These results should be taken into consideration by civil engineers and decision-makers for designing earthquake resistant structures.

Hydrochemical characteristics and evaluation of the granite aquifer in the Alwadeen area, southwest Saudi Arabia

This study was carried out in the Alwadeen area of Khamis Mushayt district of southwestern Saudi Arabia to evaluate the hydrochemical characteristics of the shallow hard rock aquifers. These hard rock aquifers mostly comprise granites and contain significant quantities of groundwater that complement the available groundwater from the unconsolidated alluvial sediments in the nearby wadis. The field investigation indicates two main fracture sets which intersect each other and are oriented in the west-northwest and east-west directions. The granitic rocks in the area are intruded by coarse-grained and quartz-rich monzogranite and pegmatite veins. Hydrogeologically, the fracture systems are important since they facilitate the groundwater storage and assume the transmissive function during times of groundwater abstraction. Given the fact that groundwater in the fractured rock aquifers generally occurs at shallow depths, it may be exposed to contamination from surface and/or near-surface sources, and it is therefore important to evaluate its quality. To this end, a hydrochemical analysis was carried out on six groundwater samples collected from the area. The hydrochemistry revealed that the groundwater is fairly fresh, and facies analysis reveals mixed Na-Cl and Ca-Mg-Cl-SO4 types. Overall, the results reveal that the groundwater is saturated with calcite and dolomite, but unsaturated with gypsum and halite. The degree of salinity increases in the direction of the groundwater flow due to increased rock-water interaction.

Automatic identification of fake patterns caused by short-width wavelets in seismic data

Despite the popularity of using the Haar wavelet filter in many applications, it sometimes introduces fake patterns into the multi resolution analysis (MRA) of seismic data. In this work, we compared different wavelet filters to demonstrate that these patterns are fake and not part of the original waveforms and to show that they are a result of using the Haar wavelet filter as a short-width wavelet. To achieve this, many seismic waveforms from two different sources: the Egyptian National Seismic Network (ENSN) and the High Sensitivity Seismograph Network Japan (Hi-net) are used with different wavelet filters. We propose an algorithm based on an autoregressive (AR) model to detect these patterns automatically and fully.

Structural development of northwest Saudi Arabia using aeromagnetic and seismological data

High resolution aeromagnetic and seismological data constrained by field-based structural investigations have been used to map and delineate the structural elements that affected and shaped the Midyan area in the northwest part of Saudi Arabia. The area was divided into four major domains defined by NNE, NNW, NW and ENE trending faults identified by trends, patterns and intensity of magnetic anomalies. The ENE trending left-lateral strike-slip faults intersected by NNE trending faults are the predominant tectonic features in the Gulf of Aqaba coastal area and stop at the boundary of a central domain characterized by complexity in the pattern and intensity of magnetic anomalies, that may be attributed to heterogeneity of basement rocks containing complex igneous rock suites including diorite, gabbro, ultramafic and alkali granitic rocks. This domain is characterized by the presence of narrow linear magnetic anomalies that extend for kilometers in an NNW direction, indicating dikes intruded through NNW trending faults. These dikes become WNW-oriented near their northern termination by transfer of movement to WNW-oriented faults marking the northern termination of the Red Sea rift. It is believed that this fault zone is still experiencing neotectonic activity, as evident from recorded seismicity. The aeromagnetic structural results coincide with fault plane solutions for the largest earthquakes, confirming aeromagnetic interpreted trends and illustrating mixed mechanisms between extensional and strike-slip faulting. Thus the study area displays different mechanisms associated with different tectonic trends which show clearly in the structural patterns of the area.

Assessment of soil-structure resonance in southern Riyadh City, Saudi Arabia

Because of the site response effects can increase earthquakes damage, the assessment of soil–structure interaction is an important parameter to reduce seismic risk at a specified location. Southern Riyadh residential area is one of the densely populated districts of Riyadh city, so protection of these structures with human who lives in these buildings is of utmost importance. This is achieved through assessment of soil-structure resonance in this area. Microtremor measurements have been conducted at ten free-field sites and inside four buildings. The horizontal-to-vertical spectral ratio (HVSR) technique has been applied in order to assess the fundamental frequencies of the sediments, beside the longitudinal and transverse fundamental frequencies of each building based on the amplitude spectra and the floor spectral ratio (FSR) methods. In case of the building frequency is close to a nearby free-field fundamental frequency, a potential soil-structure resonance is present. The results clarified that the surveyed buildings have low danger level of soil-structure resonance.