<p>Volcanic ash and Moringa oleifera (M. oleifera) were investigated as indigenous materials for drinking water treatment based on problems identified at Kampala and Masaka water treatment plants in Uganda. Coagulation experiments were done using swamp raw water at Masaka National Water & Sewerage Corporation water treatment plant and pilot-scale filtration experiments carried out at Ggaba II (Kampala) water treatment plant. The results from the study indicated that there were both operational and design handicaps at the treatment plants in Kampala. There is need to modify the filtration and clarification units to enable production of water meeting both the national and international standards. At Masaka water treatment, there was increase in trihalomethanes concentration as a result of pre-chlorination. Following aeration and pre-chlorination processes, the average increase of total trihalomethanes concentration was over 4000% with over 99% being chloroform. Preliminary results from the jar test experiments indicated that use of alum with MOCSC as coagulant aid is promising as a first stage in the treatment train for waters with a humic materials and high content of iron, typical of swamp water sources. This would probably eliminate the formation of unwanted by-products by eliminating the pre-chlorination process. Assessment of the characteristics of the volcanic ash showed that it meets the requirements for a filtration material; and results obtained from the pilot study showed that it was a suitable alternative material for use in a dual media filtration system. There was an increase in the filter run length of about two and half fold in the dual media filtration column compared to the mono medium column. Both columns produced similar water quality levels. Therefore, conversion of the rapid sand filters at Ggaba and similar water treatment plants in the country to dual media (volcanic ash on top of sand) systems would probably significantly improve the performance of the filtration systems.</p>

Title from PDF of title page. / Document formatted into pages; contains 200 pages. / Thesis (M.A.)--University of South Florida, 2003. / Includes bibliographical references. / Text (Electronic thesis) in PDF format. / ABSTRACT: How people pereceive the risks associated with natural hazards contributes to their willingness to take protective action. Such action may be constrained by prevailing socio-economic and place-specific conditions that restrict or inform the choice of protective measures available to the individual. Vulnerability to the impacts of extreme geophysical events increases when the range of alternatives is limited or misinformed. Many evacuees from a potentially violent volcanic eruption in Ecuador returned to their home town of Banos while it was still under an evacuation order in 2000 and considered to be a high risk area by officials. / ABSTRACT: The research examined four main questions: (1) What economic conditions confronted Baños evacuees? (2) What political or other social events occurred while they were evacuated that limited their perceived range of options? (3) What information was available about prior eruptions of the volcano and other local natural hazards? and (4) What were the characteristics of the economic base of Baños? These questions were investigated using data from interviews with evacuees, government and non-governmental officials, census and other statistical information, scholarly texts and newspaper reports. The research suggests that economic conditions made it extremely difficult for people to relocate to other communities. When a violent eruption did not occur immediately, and few direct impacts of the eruptions were experienced in Banos, many people chose to return home in an effort to reestablish themselves economically. / ABSTRACT: These people perceived the volcano hazard in Baños to be far less threatening than the economic destitution associated with evacuation. This perception may have been influenced by factors other than the socio-economic context, including efforts of political leaders and tourist business owners to effect the town's economic recovery. These efforts included an aggressive publicity campaign that minimized the risk posed by the volcano. Besides encouraging tourists to return, the campaign also encouraged evacuees to do so. Finally, among some residents, religious beliefs may have contributed to perceptions that they would not be harmed in the event of an explosive eruption. / System requirements: World Wide Web browser and PDF reader. / Mode of access: World Wide Web.

Perched water zones have been identified in the fractured, welded tuff in the semiarid to arid environments of Yucca Mountain, Nevada and near Superior, Arizona. An understanding of the formation of such zones is necessary in order to predict where future perched water might form at Yucca Mountain, the proposed site of a high-level nuclear waste repository. The formation or growth of a perched zone above a repository is one factor of the factors to be considered in the risk assessment of the Yucca Mountain site. The Apache Leap Research Site (ALRS) near Superior, Arizona is a natural analog to the Yucca Mountain site in terms of geology, hydrology, and climate. Perched water has been identified over an area of at least 16 km² in the Apache Leap Tuff, a mid- Miocene fractured, welded ash-flow tuff. A primary goal of this investigation was to characterize the physical and hydrologic properties of the tuff in the region above and including the perched zone, and to evaluate those characteristics to develop a model for a perching mechanism in the tuff. A second goal was to determine what fraction of water entering a watershed reaches the subsurface, to potentially recharge the perched zone. The Apache Leap Tuff has been subject to considerable devitrification and vapor phase crystallization, which dominate the character of the rock. With depth to the perched zone, pumice fragments become increasingly flattened and segregated; the pumice fragments are the primary locations of porosity in the rock, therefore porosity also becomes greatly reduced with depth, to the extent that the rock matrix is virtually impermeable at the perched water zone. Fractures are the primary pathways by which water moves through the rock; fracture hydraulic conductivity values were determined to be nine orders of magnitude greater than measured matrix hydraulic conductivity at the perched zone. An increase in fracture filling by silica mineralization beneath the perched zone reduces the secondary permeability, enhancing the formation of perched water. Thus, the primary mechanisms for the formation of the perched zone include fracture flow bringing water into the subsurface, combined with extremely low matrix hydraulic conductivity at depth, and reduced secondary permeability by filled fractures and lower fracture density. Water budgets were calculated for two years in a 51.4-ha watershed. Direct measurements were made of precipitation and runoff', evapotranspiration was both directly measured, and modeled based on measurement of a number of weather parameters. Infiltration was calculated as the residual of precipitation after runoff and evapotranspiration were removed. Infiltration was determined to be less than 10% of the annual water budget; evapotranspiration removes on the order of 90% of precipitation on an annual basis.

No description available.

Composition and texture of the Middle and Late Eocene volcanic, volcaniclastic, and volcanic-sedimentary rocks in the Bijgerd-Kuh e Kharchin area, in the Uromieh-Dokhtar zone northwest of Saveh, Iran, suggest the complexity of the magmatic system that involved multiple eruptions from one or more sources. Hydrated volcanic fragments in hyaloclastic rocks, and the presence of a sequence of shallow and intermediate-depth marine microfossils, suggest that the Middle Eocene units were erupted in a marine basin. The bimodal volcanism of the Late Eocene is distinguished by the presence of four alternating sequences of hyaloclastite lava and ignimbrite. The REE patterns show spatial homogeneity and temporal heterogeneity in the composition of all the Late Eocene sequences, suggesting origination of magma from varying sources that erupted at different times. The trace element distributions of the hyaloclastites and ignimbrites are compatible with those evolved through fractional crystallization of the lower and upper continental crust, respectively.

No description available.

Volcanic eruptions are powerful natural events which impact strongly on society. As human populations grow and expand into volcanically active areas, their exposure and vulnerability to volcanic hazards is also increasing. Of all volcanic hazards, ashfall is the most likely to impact lifelines because of the large areas affected. The widespread dispersal of ash can cause large-scale disruption of vital infrastructure services, aviation, and primary production. Electric power supply is arguably the most crucial of modern infrastructure systems, especially considering the dependence of other sectors on electricity to maintain functionality. During and immediately after ashfalls, electric power systems are vulnerable to a number of impacts, but disruption from volcanic ash-induced insulator flashover (unintended, disruptive electrical discharge) is most common. This thesis investigates the vulnerability of electric power systems to volcanic ashfall by examining impacts to the different sectors of the modern power system and exploring appropriate mitigation strategies. Analogue laboratory trials using a pseudo (synthetic) ash are undertaken to verify the environmental, volcanological and electrical parameters that most affect electrical conductivity and therefore the flashover mechanism in these experiments. While dry ash is highly resistant to the flow of electric current, increasing moisture content, soluble salt load, and compaction (bulk density) will reduce this resistance and, in turn, increase the potential for flashover. Volcanic ash is an acute form of airborne pollution for areas downwind of active volcanoes. Results from laboratory experiments in this thesis suggest that insulator pollution (volcanic ash) performance (dielectric strength) is primarily dictated by (1) the conductivity of the ash, and (2) insulator material, profile (shape) and dimensioning. Composite polymer insulators tested herein effectively minimise sinusoidal leakage current and partial discharge activity and also exhibit higher pollution performance when compared to ceramic equivalents. Irrespective of insulator material, however, the likelihood of flashover increases significantly once the bottom surface of suspension insulator watersheds become contaminated in wet ash. The thesis investigates the vulnerability (hazard intensity/damage ratio) of electric power systems to volcanic ashfall hazards. Identification, analysis, and reduction of the risk of ashfall impacts to power networks is explored as a part of holistic volcanic risk assessment. The findings of the thesis contribute to the readiness, response and recovery protocols for large electric power systems in volcanic disasters; which directly affects the functional operation and economics of industrial and commercial society.

This study presents a theoretical GIS model to investigate the relative impacts of geomorphic and environmental factors that govern the occurrence of landslides on the slopes of Mount Cameroon and its surrounding areas. The study area is located along the Cameroon Volcanic Line (CVL), a major structural feature that originates from the south Atlantic and continues into the continental landmass. The quite frequent seismic activity, geologic character, humid tropical climate and high human pressure on hill slopes are the major factors behind the occurrence of landslides in Mount Cameroon. This paper, therefore, underscores the necessity of in-depth follow-up studies concerned with landslides prevention and management based on the relevance of sufficient reliable field methods in landform geomorphology and interpretation. As much is yet to be done to acquire data for structural and surface geology, hydrology, geomorphic processes and physiography of Mount Cameroon, it is difficult at this point in time to considerably apply suitable methods using GIS that would enable identifying and delineating the landslide-prone areas. In addition, the application of environmental surface monitoring instruments will not be meaningful without a clear presentation of which areas are a cause for concern (given that the employment of any slope stability monitoring and rehabilitation efforts will be only possible after appropriate problem-area identification has been done). Consequently, based on the writer’s previous work in the Mount Cameroon area and available related literature, a methodology using GIS is proposed, which provides the capability to demonstrate how the impact of individual or collective geomorphologic site-specific factors on landslides occurrence could be justified. Considering that digital data may not be readily available, a procedure for the creation of data and analysis of themes is proposed and illustrated. The factors analysis approach in landslides analysis may be cheaper and easier to employ in Mount Cameroon and similar problem regions in developing countries (given that there may be problems of limited financial resources and available expertise in GIS technology and applications). The study underscores and recommends the necessity for a later practical implementation with the availability of adequate resources.

[Truncated abstract] The Neoarchean (2800 to 2600 Ma) Eastern Goldfields Superterrane (EGST) comprises elongated belts of deformed and metamorphosed volcanic and sedimentary rocks intruded by granitoids. The Superterrane is made up of five distinct tectonostratigraphic terranes. From west to east these are the Kalgoorlie, Gindalbie, Kurnalpi, Laverton and Duketon Terranes. The Kalgoorlie Terrane is characterised by 2720 to 2680 Ma marine mafic-ultramafic volcanic successions interlayered with, and overlain by, 2710 to 2660 Ma dominantly trondhjemite-tonalite-dacite (TTD) dacititic volcaniclastic rocks (Black Flag Group). The adjacent Gindalbie and Kurnalpi terranes are characterised by 2720 to 2680 Ma calc-alkaline volcanic successions representing oceanic island arcs. To the west of the EGST, the Youanmi Terrane is characterised by older, dominantly 3000 to 2900 Ma greenstone rocks and complex granitoid batholiths derived from older crustal sources. The southern Kalgoorlie Terrane comprises five elongate NNW-trending tectono-stratigraphic domains. Three principal marine komatiitic to basaltic suites, collectively referred to as the Kambalda Sequence, are present, including the wellpreserved massive to pillowed Lower and Upper Basalt Sequences, separated by the Komatiite Unit, as well as numerous dyke suites. The Lower Basalt Sequence comprises the Woolyeenyer Formation, Lunnon, Wongi, Scotia, Missouri Basalts and Burbanks and Penneshaw Formations, whereas the Upper Basalt Sequence contains the Paringa, Coolgardie, Big Dick, Devon Consols, Bent Tree, and Victorious basalts. ... Instead, the data suggest that discrete PGE-bearing phase (s) fractionated from the basaltic magmas. Such phases could be platinum group minerals (PGM; e.g. laurite) and/or alloys, or discrete PGE-rich nuggets. In summary, data on the three magmatic sequences record decompression melting of three distinct mantle sources: (1) long-term depleted asthenosphere for prevalent depleted tholeiitic and komatiitic basalts, and komatiites; (2) long-term enriched asthenosphere for Paringa Basalts and similarly enriched rocks; and (3) shortterm enriched continental lithospheric mantle (CLM) for HREE and Al-depleted dykes. Some of these rocks were contaminated by TTD-type melts. Taken with the existing geophysical and xenocrystic zircon data, the most straightforward interpretation is eruption of a zoned mantle plume at the margin of rifted continental lithosphere. The Kalgoorlie Terrane extensional basin was subsequently tectonically juxtaposed with the adjacent arc-like Gindalbie and Kurnalpi Terranes at approximately 2660 Ma at the start of orogeny in a Cordilleran-style orogen to form the EGST. Collectively, uncontaminated basalts have Nb/Th of 8-16, compared to 8-12 reported for the Lunnon basalts in a previous study. To a first approximation these asthenosphere melts are complementary to average Archean upper continental crust with Nb/Th =2, consistent with early growth of large volumes of continental crust rather than models of steady progressive growth.

Mémoire (M.Sc.A.)-- Université du Québec à Chicoutimi ; 1986. / "Mémoire présenté pour l'obtention du grade de maîtrise es sciences appliquées" CaQCU Document électronique également accessible en format PDF. CaQCU