Detailed isophotometry of some galaxies,I

Results from a detailed isophotometric survey of NGC 5595, NGC 5597, NGC 5605, and NGC 7769 are given. It includes isophotic maps, luminosity profiles and ellipticity curves as well. Scanning of these galaxies was done in theB andV colours.     

Soft soil mapping using Horizontal to Vertical Spectral Ratio (HVSR) for seismic hazard assessment of Chandigarh city in Himalayan foothills,north India

The populated and expanding city of Chandigarh is located in the foothills of Himalaya, near the potentially active Main Frontal Thrust (MFT). A hazard assessment for this city is consequently of major importance. Thick sediments underlies the city and that can potentially amplify the earthquake shaking and contribute to an earthquake disaster in the city. The present study applies the Horizontal to Vertical Spectral Ratio (HVSR) ambient noise methodology to estimate the resonance frequency of the soft sediments and to obtain a first order estimate of sediment thickness. The study indicates that the soil thickness range from 30 to 270 m and that the resonance frequencies vary from 0.236 to 1.479 Hz. A smooth correlation function between soil thickness and resonance frequency is found, indicating relatively homogeneous soil.     

Transport of moderately sorted gravel at low bed shear stresses: The role of fine sediment infiltration

A reliable estimation of sediment transport in gravel‐bed streams is important for various practical engineering and biological studies (e.g., channel stability design, bed degradation/aggradation, restoration of spawning habitat). In the present work, we report original laboratory experiments investigating the transport of gravel particles at low bed shear stresses. The laboratory tests were conducted under unsteady flow conditions inducing low bed shear stresses, with detailed monitoring of the bed topography using a laser scanner. Effects of bed surface arrangements were documented by testing loose and packed bed configurations. Effects of fine sediments were examined by testing beds with sand, artificial fine sand or cohesive silt infiltrated in the gravel matrix. Analysis of the experimental data revealed that the transport of gravel particles depends upon the bed arrangement, the bed material properties (e.g., size and shape, consolidation index, permeability) and the concentration of fine sediments within the surface layer of moving grains. This concentration is directly related to the distribution of fine particles within the gravel matrix (i.e., bottom‐up infiltration or bridging) and their transport mode (i.e., bedload or suspended load). Compared to loose beds, the mobility of gravel is reduced for packed beds and for beds clogged from the bottom up with cohesive fine sediments; in both cases, the bed shear stress for gravel entrainment increases by about 12%. On the other hand, the mobility of gravel increases significantly (bed shear stress for particle motion decreasing up to 40%) for beds clogged at the surface by non‐cohesive sand particles. Copyright © 2017 John Wiley & Sons, Ltd.     

Accuracy improvement of ASTER stereo satellite generated DEM using texture filter

The grid DEM(digital elevation model) generation can be from any of a number of sources:for instance,analogue to digital conversion of contour maps followed by application of the TIN model,or direct elevation point modelling via digital photogrammetry applied to airborne images or satellite images.Currently,apart from the deployment of point-clouds from LiDAR data acquisition,the generally favoured approach refers to applications of digital photogrammetry.One of the most important steps in such deployment i...     

Seismic vulnerability assessment in the new urban area of Diriyah Governorate,Riyadh, Saudi Arabia

Nine seismic refraction profiles were conducted and processed to study the near-surface sediments in the new urban area of Diriyah. The 2D geoseismic models illustrate two layers: a surface layer of soft sediments and weathered to hard limestone bedrock. Moreover, microtremor measurements were performed at 38 sites for 40 min using three-component seismographs and processed to assess the peak spectral amplitude and the corresponding fundamental resonance frequency. The seismic vulnerability index at each measurement site was estimated. These results correlate well with the geotechnical borehole data. The north-western zone is highly vulnerable due to the great thickness of the soft sediments.     

Emergence of the semi-empirical technique of strong ground motion simulation: A review

High frequency ground motion simulation techniques are powerful tools for designing earthquake resistant structures in seismically active regimes. Simulation techniques also provide the synthetic strong ground motion in the regions where actual records are not available (Kumar et al. 2015).These techniques require several parameters of earthquake and other seismic information proceeding to the simulation. Practically estimation of parameters is a tough task, particularly in a region with limited information. This demands a simulation technique based on the easily estimated parameters for a new site. The purposes of this paper are to briefly review existing simulation techniques and to discuss in detail the new, simple and effective semi-empirical technique (Midorikawa 1993) of strong motion simulation.     

Analysis of sedimentary facies and depositional environments of Paleogene sequence of Cambay basin,India

A study on the sedimentary facies characterization and depositional environment interpretations for the K#Field (K-Oil Field) in Cambay petroleum basin of western onshore, India was conducted based on the sub-surface data from drilled wells, including well logs, borehole images, cores and the regional knowledge of the basin. In this work, an effort is made to integrate the current data from seismics and well logging, to study and analyze its depositional environments and establish the petroleum systems. The study regions for the present work are K45 and K48 blocks. The target strata includes 2 oil-bearing formations of Paleogene, which is about 3600 ft; they are M#Fm (M-Formation) of the Eocene and N#Fm (N-Formation) of Oligocene, subdivided into 11 zones. The sediment fill is mostly of Tertiary. The research attempts to decipher the oil - depositional source correlation problems of the basin. Sedimentary models were established referring to the core analysis, core photographs and well logs. Reservoir and heterogeneity study included reservoir lithology features, physical properties and pore structure features.Well facies analysis of oil well WELL-0297 and WELL-0129 was done and the results were analyzed for further drilling of new wells for oil and gas exploration. The study found that the Eocene, Oligocene, Miocene and Paleogene are fluviatile facies sand and mud interbed sediment with the thickness 2000-4000 ft, which are main oil-bearing formations in these areas. Studies concluded that the fluvial reservoirs of the K#Field are characterized by large variations from laterally extensive bodies with good interconnectedness and high net-to-gross ratios, multi-storey ribbon bodies with poor interconnections and low net-to-gross ratios.     

Seismicity of Sinai Peninsula, Egypt

The Sinai Peninsula has a triangular shape between the African and Arabian Plates and is bounded from the western and eastern borders by the Gulf of Suez and Gulf of Aqaba–Dead Sea rift systems, respectively. It is affected by strong and destructive earthquakes (e.g., March 31, 1969 and November 22, 1995) and moderate earthquakes (m _b?>?5) throughout its history. After the installation of the Egyptian National Seismic Network (ENSN), a great number of earthquakes has been recorded within and around Sinai. Consequently, the seismogenic source zones and seismotectonic behavior can be clearly identified. Available data, including both historical and instrumental (1900–1997), have been collected from national and international data centers. While the data from 1998 till December 2007 are gathered from ENSN bulletins. The seismogenic source zones that might affect Sinai Peninsula are defined more precisely in this work depending on the distribution of earthquakes, seismicity rate (a value), b value, and fault plane solution of the major earthquakes. In addition, the type of faults prevailed and characterized these zones. It is concluded that the Gulf of Aqaba zone–Dead Sea transform zone, Gulf of Suez rift zone, Cairo–Suez District zone, and Eastern Mediterranean dislocation zone represent the major effective zones for Sinai. Furthermore, there are two local seismic zones passing through Sinai contributing to the earthquake activities of Sinai, these are the Negev shear zone and Central Sinai fault (Themed fault) zone. The source parameters, a and b values, and the maximum expected moment magnitude have been determined for each of these zones. These results will contribute to a great extent in the seismic hazard assessment and risk mitigation studies for Sinai Peninsula to protect the developmental projects.     

Physical model experiments for sediment supply to the old Rhine through induced bank erosion

A mobile-bed, undistorted physical model （1：40） has been used to investigate different sediment supply strategies to the Old Rhine through bank protection removal and modifications of groyne dimensions and configuration, which cause bank erosion. This trained channel was previously the main bed of the upper Rhine downstream of Basel （Switzerland）, but it has an artificially low flow regime since the construction of the Grand Canal d＇Alsace, a navigation canal, and a flow control dam at Kembs （France）. Training works and subsequent channel incision have also greatly reduced sediment transport rates and created a heavily armoured bed. The modelled pilot site has a groyne field on the left bank. Results show that the currently existing groynes at the site are not effective in creating high bank-side velocities conducive to bank erosion, even for flow rates significantly higher than the mean annual flow rate. The river bank has also proved to be more resistant than previously thought, allowing long stretches of bank protection to be safely removed. The physical model testing process has produced a new configuration for the groyne field, where two higher, larger island groynes are placed further apart than the three existing attached groynes. This innovative approach has proved effective, causing bank erosion for flow rates below the mean annual flow rate, with consistent erosion being observed. It has also been found that such a configuration does not pose a hazard for the Grand Canal d＇Alsace, which is situated next to the Old Rhine, through excessive bank erosion during high flow events.