Causes of rockfalls in AI-Huwayshah area, Yemen

According to topography of Yemen, most areas and villages are located at obligated crest, toe of mountain and under cliffs. Therefore Al-Huwayshah consisting of Tawilah sandstone group is characterized by steep slope reach to 90℃ in some areas. This area is affected by strong tectonic movements and faults that occurred during the geological epochs. This effect enhances to find out fractures and joints as well as the rocks become brittle and ready to slide depending on the position of area. And there are some fractures and joints on the surface of the areas due to tectonic movement associated with opening the Red Sea and Gulf of Aden. The rainfalls, fractures, joints, earthquakes, gravity, vegetations, temperatures and human activities play a big role in the processes of rockfalls and landslides in this area. All those factors are considered as the basic causes and catalyzed factors for occurrence of rockfall in the studide area. In addition, the authors carried out laboratory test for many rock samples to get the physical properties of the rocks.     

Hydrocarbon Generation Potential of the Organic-Rich Naifa Formation,Say’un–Masila Rift Basin,Yemen: Insights from Geochemical and Palynofacies Analyses

Natural Resources Research - The Say’un–Masila rift, one of the most important basins of Yemen, contains unconventional resources of organic-rich rocks. In the present work, geochemical...     

Structure of time variations in carbon dioxide in the atmospheric thickness over central Eurasia (Issyk Kul Monitoring Station)

The results are presented of statistical analysis of the data obtained from the 1980–2006 systematic measurements of the volume concentration of carbon dioxide in the atmospheric thickness over central Eurasia. The trends of both monthly and yearly means of CO₂ concentration are determined. During these 26 years, the yearly mean concentration increased by ～42 ppm at a mean rate of (1.56 ± 0.18) ppm per year and reached ～382.7 ppm. General statistical characteristics are found. The distribution function of the monthly mean concentrations of CO₂ is characterized by the presence of a second maximum and a bias of the principal mode toward large values, and the mean (over the measurement time) monthly concentration and the median almost coincide. The distribution function of the yearly mean concentrations of CO₂ is close to a normal distribution, and the mean (over the measurement time) yearly concentration, the median, and the mode also coincide. The trends of short-and long-period variations in the carbon dioxide concentration and their possible relation to a number of geophysical phenomena are revealed. Spectral analysis of the measuring data on CO₂ revealed oscillations with periods of 4, 6, 12, 15, 21, 29, 40, 53, 84, and 183 months. A statistical model with the parameters of these oscillations describes the experimental monthly mean concentrations of carbon dioxide with an rms deviation of 2.3 ppm (±0.6% of the mean over the entire period 361.9 ppm) and the yearly mean concentrations with an rms deviation of 0.9 ppm (～±0.3%).     

Monitoring of coastline changes along the Red Sea,Yemen based on remote sensing technique

The coastline changes along Yemen's the Red Sea (Al-muka, Al-khohah, Al-tiaf, Ras Katib and AlUrji spits) were studied using a series of landsat images (MSS, TM and ETM + , 1972, 1989, 2000, 2006),coup...     

Carbon dioxide content in the atmospheric thickness over central Eurasia (Issyk Kul Monitoring Station)

The refined data obtained from the spectroscopic measurements of carbon dioxide in the column of the continental atmosphere over the Issyk Kul Monitoring Station during the period 1980–2006 and the results of their comparison with the data obtained from the measurements of carbon dioxide in air samples and with the mean zonal empirical model of the Climate Monitoring and Diagnostics Laboratory (CMDL) are given. Seasonal variations and a long-term trend of carbon dioxide concentration in the atmospheric thickness over a 25-year period of measurements are analyzed. The monthly mean concentration of CO₂ is increased by ～40.5 ppm, and the linear-trend index is 1.62 ppm per year. The results of the aircraft measurements of CO₂ concentration in air samples are, on the average, in agreement with the data obtained from the spectroscopic measurements of carbon dioxide concentration in the atmospheric column. The CO₂ concentration in the surface air varies from day to day, and only its minimum values coincide with the CO₂ concentration in the atmospheric thickness. The results of measurements of CO₂ concentration in the atmospheric thickness and in the atmospheric surface layer over the KZD and KZM stations nearest to each other are, on the whole, in disagreement; moreover, the KZD and KZM data are inconsistent. The CO₂ concentration in the atmospheric thickness is, on the average, 1–2% higher than that obtained with the CMDL model for 42.6° N latitude. The coefficient of correlation between the measurement results and model data is high (r= 0.95).     

Diagenetic and metamorphic history of the Umm Nar BIF,Eastern Desert,Egypt

The Umm Nar BIF was formed in a sedimentary environment. It is confined to an upper stratigraphic zone of pre-Pan-African metamorphosed shelf deposits. During the Pan-African deformational history, the BIF and the host metasediments were tectonically' overlain by ophiolitic melange succession. The metasediments and the mélange were subjected to a major folding phase and then thrust over the “Shaitian” sheared granite, prior to the intrusion of syn- to late- orogenic granitoids. The BIF is divisible into two main types: oxide-bands including magnetite and hematite, and oxide-silicate bands including magnetite, hematite and stilpnomelane. The associated gangues are quartz, calcite, epidote, garnet, plagioclase, graphite and muscovite. Rhythmic banding and lamination, cross-lamination and flaser structure are the most prominent primary features in the IF bands. The iron minerals and the associated gangue show a variety of textural aspects and microscopic interrelationships which indicate successive episodes of mineral accumulation and formation, involving deposition, recrystallization, blastic growths, overgrowths, replacement and deformations, during continuous burial and subsequent tectonic deformations. Editorial handling: DR     

Subvertical clusters of earthquake hypocenters unrelated to the tectonic structure of the Earth’s crust

The existence of a subvertical pillar-like cluster of earthquake hypocenters is established in the central part of the Garm geodynamic test area (Tajikistan). Seismotectonic deformation of the subvertical uniaxial extension prevails in the lower part of the cluster. This cluster is characterized by the absence of any relation to elements of the tectonic structure of the region. It is supposed that this element of the seismogenic structure of the region represents a channel of supply of deep fluids. Clusters of aftershock sources, close in morphology and position, are known in connection with the Altai, Neftegorsk, and Kultuk earthquakes. The subvertical but flattened-out in plan accumulations of aftershocks, unrelated to any elements of the tectonic structure of the Greater Caucasus, correspond to the Dagestan earthquake. Some other accumulations of earthquake hypocenters, so-called nests, such as the Vrancea and Hindu Kush ones, can be probably regarded as formations of a similar type.     

Stability evaluation and protection of slope for Laosongling-Yanji Highway

The authors analyzed the engineering geological characteristics of the slope of the study area (K75+840-K76+340). Two typical cross-sections have been chosen to analyze the failure modes after the excavation of the highway. Different types of the failure modes have been calculated and analyzed. The results show that some dealing methods have been advised to ensure the stability of the slopes.     

Variations in nitrogen dioxide in the atmosphere over central Eurasia (Issyk Kul Monitoring Station)

The results of an analysis of data on the total content of nitrogen dioxide in a vertical atmospheric column are given. These data have been obtained from measurements with the twilight method over a period of 25 years. The monthly and annual means (the arithmetic means of both morning and evening values) of NO₂, on the whole, have increased by ～6% in spite of its rapid decrease in 1991–1995 due to the Pinatubo eruption. The linear-trend index amounts to 0.23% per year. The annual mean over the entire observation time is equal to (3.18 ± 0.05) × 10¹⁵ mol/cm², and the amplitude of seasonal variations amounts to (2.39 ± 0.04) × 10¹⁵ mol/cm². Spectral analysis of the experimental data has revealed compound oscillations with periods of 6 to 253 months, the values of which do not contradict published data. Most of these oscillations are nonharmonic. A simple statistical model satisfactorily describes time variations in the monthly and annual means of NO₂ with rms deviations of ～4% and 1%, respectively.     

Multi‐directional response of unreinforced masonry walls: experimental and computational investigations

This paper describes the results of an experimental and numerical study that focused on multi‐directional behavior of unreinforced masonry walls and established the requisite of the related proposed design equations. The tests were conducted following several sets of multi‐directional loading combinations imposed on the top plane of the wall along with considering monotonic and cyclic quasi‐static loading protocols. Various boundary conditions, representing possible wall–roof connections, were also considered for different walls to investigate the influence of rotation of the top plane of the wall on the failure modes. The results of the tests were recorded with a host of high precision data acquisition systems, showing three‐dimensional displacements of a grid on the surface of the wall. Finite element models of the walls are developed using the commercial software package ABAQUS/Explicit compiled with a FORTRAN subroutine (VUMAT) written by the authors. The experimental results were then used to validate the finite element models and the developed user‐defined material models. With the utility of validated models, a parametric study was performed on a set of parameters with dominant influence on the behavior of the wall system under in‐plane and out‐of‐plane loading combinations. The experimental and numerical results are finally used to investigate the adequacy of ASCE 41 empirical equations, and some insights and recommendations are made. Copyright © 2016 John Wiley & Sons, Ltd.