In situ tests for ice strength measurements

Ice effects have caused extensive damage. Enormous forces have been recorded. On the other hand, ice has been used as a structural material under various situations. To use ice beneficially and to assess the danger of ice forces, it is necessary to know the mechanical properties of ice.Results from the large number of ice tests carried out in laboratories show the difficulties of sampling and testing procedures. Most of the tests have not reproduced faithfully enough the conditions existing in nature. To obtain adequate results, laborious and slow samplings and preparations of test specimens have been necessary. Recently, extensive use has been made of in situ tests in order to reduce the number of factors whixh can induce errors in measurements. Large scale tests have simulated actual structures. General ice properties have become available from small-scale in situ tests. Since these tests give rapid results, a large number are already available with a good coverage of field conditions.A theoretical basis has been devised for these in situ tests which measure essentially the unconfined and confined compressive strengths of ice, and practical devices have been developed to execute these tests. A correlation of measurements from laboratory tests and in situ tests has established a link between natural and artificial environments. Brittle elastic and clastic theories have been applied, to find the best correlations for ice tests. Test results have been related to the mechanical properties as used in engineering practice.A very summary conclusion of results is that cold sea ice and cold fresh water ice are both very strong. However, depending on the load rate, ice can be quite brittle, which mitigates dangerous effects from ice action against massive structures.     

Native aluminium (spherules and particles) in the Central Indian Basin sediments: Implications on the occurrence of hydrothermal events

We have sampled particles of native aluminium (Al°) in two sediment cores from the Central Indian Basin (CIB). The cores are geographically separated but are located at the base of two seamounts. The native Al° particles occurring as grains and spherules, have an average Al content of  95% and are associated with volcanogenic–hydrothermal material. Morphologically and compositionally, the specimens are similar to those reported from the East Pacific Rise. After ruling out several processes for the presence of the native Al°, we hypothesize that during progressive melting of magma, a basaltic magma is produced which has high contents of reductants such as methane and hydrogen, and a low oxygen fugacity. During the upward migration of such magma, reduction to metallic aluminium and the formation of native Al° particles takes place.     

Seasonally and spatially referenced estimates of recreational shore-angling effort,catch composition,catch rates and total catch in the Goukamma Marine Protected Area,South Africa

A roving creel survey of the recreational shore fishery along the 16.4-km coastline in the Goukamma Marine Protected Area on the south coast of South Africa was conducted from 2009 to 2011. Some 838 patrols were stratified equally among months, areas and years, but intentionally biased towards weekends. Angler densities at Buffalo Bay and Groenvlei were 0.59 and 0.28 anglers km?1, respectively. Weekend densities were double to quadruple weekday densities and fishing during winter was more popular than during summer. Area, habitat and distance to access points explained variation in angler densities. Shannon–Wiener diversity in catches declined from 2.18 in an earlier (1993–2002) survey to 1.79. Although the order of species abundance in the catches remained largely unchanged, blacktail Diplodus capensis dominance increased to 57.3% by number, at the expense of galjoen Dichistius capensis. Habitat explained 27% of the variance in catch composition. The catch per unit effort (CPUE) for the top nine species ranged from 0.19 to 6.35 fish 100-h?1. The CPUE of all species, except spotted grunter Pomadasys commersonnii, declined. Blacktail and galjoen CPUE declined by 17% and 77%, respectively. The total catch estimate was 2 986 fish y?1. Transgressions of size limits were common. The results suggest that the fishery is overexploited and that catch rates are declining.     

Vp/Vs ratios in the Yellowstone National Park region, Wyoming

In this paper we study the variation of V_p/V_s and Poisson's ratio (δ) in the Yellowstone National Park region, using earthquakes which were well recorded by a local seismic network. We find that the average V_p/V_s value within the geothermally active Yellowstone caldera is about 7% lower than in the area outside the caldera. Within the caldera itself there may be a further 2–7% reduction of V_p/V_s in the hydrothermally active Norris Geyser Basin, the Upper and Lower Geyser Basins, and the Yellowstone Lake and Mud Volcano regions. After considering various possible causes for V_p/V_s changes, such as geologic and structural differences, thermal effects, partial melting, and hydrothermal activity, we conclude that the most plausible explanation for the observed V_p/V_s reduction is the presence of hot-water at temperatures and pore-pressures near the water steam transition in the caldera geothermal reservoirs.     

A review of crust and upper mantle structure studies of the Snake River Plain-Yellowstone volcanic system: A major lithospheric anomaly in the western U.S.A.

The Snake River Plain-Yellowstone volcanic system is one of the largest, basaltic, volcanic field in the world. Here, there is clear evidence for northeasterly progression of rhyolitic volcanism with its present position in Yellowstone. Many theories have been advanced for the origin of the Snake River Plain-Yellowstone system. Yellowstone and Eastern Snake River Plain have been studied intensively using various geophysical techniques. Some sparse geophysical data are available for the Western Snake River Plain as well. Teleseismic data show the presence of a large anomalous body with low P- and S-wave velocities in the crust and upper mantle under the Yellowstone caldera. A similar body in which compressional wave velocity is lower than in the surrounding rock is present under the Eastern Snake River Plain. No data on upper mantle anomalies are available for the Western Snake River Plain. Detailed seismic refraction data for the Eastern Snake River Plain show strong lateral heterogeneities and suggest thinning of the granitic crust from below by mafic intrusion. Available data for the Western Snake River Plain also show similar thinning of the upper crust and its replacement by mafic material. The seismic refraction results in Yellowstone show no evidence of the low-velocity anomalies in the lower crust suggested by teleseismic P-delay data and interpreted as due to extensive partial melting. However, the seismic refraction models indicate lower-than-normal velocities and strong lateral inhomogeneities in the upper crust. Particularly obvious in the refraction data are two regions of very low seismic velocities near the Mallard Eake and Sour Creek resurgent domes in the Yellowstone caldera. The low-velocity body near the Sour Creek resurgent dome is intepreted as partially molten rock. Together with other geophysical and thermal data, the seismic results indicate that a sub-lithospheric thermal anomaly is responsible for the time-progressive volcanism along the Eastern Snake River Plain. However, the exact mechanism responsible for the volcanism and details of magma storage and migration are not yet fully understood.     

Seasonal and solar cycle variations of night-time anomalous enhancements in total electron content

Seasonal and solar cycle variations of the various characteristics of night-time anomalous enhancements in total electron content (TEC) of the ionosphere are presented for a low latitude station, Hawaii by considering TEC data for a full solar cycle. All the characteristics of the TEC enhancements have seasonal and solar cycle dependence. TEC enhancement characteristics such as frequency of occurrence, amplitude and duration are positively correlated with solar activity. The possible source mechanisms for the observed enhancements are also discussed.     

Soil,landuse and land evaluation studies of Patna area Bihar

The soil and landuse surveys have been conducted in Patna area, Bihar, using aerial photos of 1:25,000 scale. Three major systems, Ganges Gandak and interfluvial plain, have been identified in the area. These were further sub-divided into levees plains and channels etc. The soils were classified according to Soil axonomy. The major land use of the area is cultivation (62.2%) (Upland, lowland and wet land crops) plantation (1.8%) habitation (16.0%), water bodies (8.8%), barren lands (9.4%) and miscellaneous (1.8%). The soils of the area have been evaluated for different land utilization types-upland crops, lowland crops, and habitation. For paddy 75.:%, upland crops 8.2% and for habitation 57%, area was found suitable.     

The solani-ganga interfluve; an application of remote sensing technique on soil resource mapping for agricultural planning

The area of the Solani-Ganga interfluve, which lies between 29°16′N to 30°15′N latitude and 77°45′E to 78°15′E longitude was undertaken for the present study using LANDSAT imagery of band 5 and 7 and the false colour composite on the scale of 1:250,000 in combination with aerial photographs (1:25,000). Major geomorphic units, e.g., Siwalik Hills. Solani-upper alluvial plain, Solani lower alluvial plain, ‘Tarai’ and Ganga alluvial plain were delineated on LANDSAT and colour composite. Sample areas selected from LANDSAT were studied on aerial photographs in details and soil physiography relationship was developed. The soils on Siwalik hills are classified as Orthents. The soils of the pledmont plain and the recent terraces of Solani river and its tributaries were Psamments, Orthents, Fluvents, Orchrepts and Aquepts. The soils of upper alluvial tract of the Ganga plain is mostly Ustalfs with inclusion of Aqualfs, while the strong hydromorphic Tarai tract consists of partly Aquepts, Ochrepts (cultivated) and partly of Aquolls, Ustolls and Ustalfs (under forest). The present study aims to pin point the nature of soil relief relationship with the help of LANDSAT imagery and aerial photographs and diagnose the intensity of the depletion of soil resources (by prevailing factors like swift run off of biykderfed torrents, fast-flow of ground water, soil creep, mass wasting) through field studies and then treat them with ecological dose of soil conservation. For agronomic development of the region, it is worked out that the present crop-combination and crop-rotation systems should be slightly modified according to its ecosystem to prevent the depletion of soil nutrients.     

Use of remote sensing techniques for agricultural land use survey,classification and planning

A critical appraisal of the need and use of remote sensing techniques for land use mapping with particular reference to Indian conditions have been made. Land use classification system based on physiography, utility, management and identification have been suggested using remote sensing techniques at different levels of mapping.