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Showing 1 to 20 of 66 for “"Volcanic ash"”.
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Mineralogical and Chemical Studies of Some Philippine Volcanic Ash Soils
Made available in DSpace on 2014-12-10T17:12:34Z (GMT). No. of bitstreams: 1 6808069.pdf: 4460870 bytes, checksum: ab122d57446fb8948f991ac3da41f5b7 (MD5) Previous issue date: 1967
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Sulfate attack on cement paste with volcanic ash : durability analysis
… of this study is to investigate the effect of volcanic ash cements when exposed to different forms of sulfate attack, specifically to sodium and magnesium sulfates. Pozzolanic volcanic ash can be a viable partial substitute for Portland Cements to develop cement paste compositions for superior …
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Revision of European Building Code En1991 for Static and Dynamic Roof Loading by Volcanic Ash
… effects of both static and dynamic loading of volcanic ash deposition on concrete roofs. The study aims to propose changes by adding additional action (i.e., volcanic ash loads) to the building regulations to make existing and future European buildings more robust. The investigation uses a …
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CO2 Adsorption On Volcanic Ash: Net Contribution Of Volcanic Eruptions To The Global Carbon Cycle
… a small percentage of the terrestrial co2 sink. Volcanic ash is virtually free of co2 when erupted and has a high surface area resulting in a high capacity for co2 adsorption. Volcanism is commonly assumed to be only a source of co2, but pyroclastic eruptions can also potentially serve as a sink. …
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Hydrological processes in volcanic ash soils : measuring, modelling and understanding runoff generation in an undisturbed catchment
… area is characterized by steep hillslopes, volcanic ash soils, undisturbed old growth forest and high rainfall amounts. The investigation of runoff generation processes in this data scarce area is of special interest as a) little is known on the hydrological functioning of the young volcanic …
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Electrical interaction between atmospheric volcanic ash and aircraft in flight : mechanisms and application for hazard detection
… has been studied since the 1940’s, and volcanic ash suspended within dispersed plumes has been a hazard to aviation since the advent of commercial jet airliners in the 1960s. This study examines the interaction of volcanic ash particles with metallic surfaces likely to be found on an …
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Characterization of volcanic ash from 2010 Mt Merapi, Indonesia eruption by neutron activation analysis and leaching analysis
… a wide range of elements present in fresh volcanic ash from a 2010 eruption in Indonesia using varied instrumental neutron activation analysis techniques. The ash was then leached into slightly acidic distilled water meant to simulate rainwater. This thesis focuses both on the methods used …
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The use of physical and chemical techniques in the identification of Tephera (volcanic ash) in the North Island, New Zealand
… particularly in areas far from the likely volcanic source. In such areas the deposits are thin, and consequently more strongly weathered, as they are more or less continually involved in soil development processes. Under such conditions lithologic resemblance of a given ash to the same …
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Leachability of uranium and other elements from freshly erupted volcanic ash and Water-soluble material on aerosols collected within volcanic eruption clouds
Includes bibliographical references (pages 78-87, 179-182).
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Hydrogeological controls of uranium and arsenic mobility in groundwater of the Pine Ridge Reservation, South Dakota
… PRR are enriched with uranium and arsenic due to volcanic ash deposits emplaced into the White River Group, which unconformably underlies the Arikaree Group. Groundwater samples were obtained for over 250 wellbores through collaboration with the Oglala Sioux Tribe and Indian Health Service. …
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The effect of sintering and CMAS on the stability of plasma-sprayed zirconia thermal barrier coatings
… lifetime. The effect of vermiculite (VM) and volcanic ash (VA) contamination on the sintering-induced spallation lifetime of PS TBCs was also investigated. The presence of both VM and VA was found to accelerate the rise in their Young’s modulus with sintering. Spallation results show that …
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Sedimentological constraints on Middle Miocene extensional tectonism of the southern Las Vegas Range, southern Nevada
… sandstone, conglomerate, megabreccia, and volcanic ash. The formation represents deposition in a shallow, permanent lake 12 to 16 Ma. Post 12 Ma, the formation was faulted by north-striking, normal faults. Subsequently, oroflexural bending along the Las Vegas Valley shear zone, rotated the …
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The Stratigraphy of Late Quaternary Deposits in the Payan Mining District, Narino, Colombia, South America
… consist of cobble or pebble gravels with thick volcanic ash caps. These gravel terrace deposits unconformably overlie a cemented volcanic tuff (Ananias Formation), and are subdivided into two formations (Antigua and Panambi formations) based on the cobble lithology and size, depth of weathering, …
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High precision U/Pb geochronology on the Cenomanian Dakota Formation, Utah : implications for paleobotany and the transgression of the Western Interior Seaway preceding Oceanic Anoxic Event 2
… Formation within the geological time scale. Volcanic ash samples interlayed with fossil bearing sandstones of the Dakota were collected from two localities in Westwater, and Henrieville, Utah. Samples were dated using isotope dilution thermal ionization mass spectrometry (ID-TIMS). The …
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Origin and distribution of selenium in the upper Cretaceous Niobrara and Pierre formations, northeastern North Dakota
… section. This suggests that the selenium had a volcanic source and accompanied the volcanic ash that formed the bentonite beds. </p><p> Soils formed from rock in the bentonitic zone above and below the Pierre-Niobrara contact can be presumed to be seleniferous and cap able of producing toxic …
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Carbon Accumulation Rates Over the Holocene in Flow Country Peatlands and the Direct Comparison of Open and Afforested Peatland Carbon Stocks Using Tephrochronology
… tephrochronology, the identification and use of volcanic ash layers to reliably match stratigraphy. We successfully applied this method to four pairs of afforested and open blanket bog sites in the Flow Country. First, ITRAX scanning was tested as a tool for finding tephra within peat and we …
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Subduction dynamics at the middle America trench : new constraints from swath bathymetry, multichannel seismic data, and ¹⁰Be
… unique tracer of shallow sediment subduction in volcanic arcs. The range in ¹⁰Be enrichment in the Central American Volcanic Arc between Guatemala and Costa Rica is not controlled by variations in ¹⁰Be concentrations in subducting sediment seaward of the Middle America Trench. Sedimentary ¹⁰Be is …
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Depositional Environments of Siliceous Laminites in the Laney Member of the Green River Formation, Sublette County, Wyoming
… sediment contained significant amounts of volcanic ash, and were deposited in a shallow, near-shore, oxygenated saline - alkaline lake environment, as inferred from (1) the association of stromatolites , mud-cracked dolomicrites and ostracodal micrite, (2) fossil occurrences of Knightia …
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Geometry-Dependent Fracture and Rebound of Particulate under Compressor-Relevant Impact Conditions
… ingest small solid particles like sand, dust, or volcanic ash. Once inside, these particles collide with engine blades at very high speeds, where they may bounce, stick, or break apart. Each of these outcomes affects how particles travel through the engine and, in turn, how they contribute to …
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