Volcanic eruptions produce a range of hazards which can impact society. The most widespread of these hazards is volcanic ash fall which can impact a range of critical infrastructure. Power systems are particularly vulnerable to ash fall hazards and the resulting impacts may lead to power supply disruption. This can lead to cascading disruption of dependent systems, such as hospitals, water and wastewater treatment plants, telecommunications and emergency services. Typically, large emergency power generator sets are used to provide emergency power supply for essential services during electrical power outages. There has been little study of what impact ash fall exposure will have on generator performance. International experience suggests large generators can experience rapid performance reduction when exposed to high concentrations of suspended or falling ash due to obstruction of air filters and radiators, causing overheating of the engine and shut down of the generator system. However, it is not clear at what ash fall thresholds generators are likely to be disrupted. This research uses custom designed empirical laboratory experiments to investigate the performance of large generators subjected to a range of volcanic ash fall types and intensities, simulating both proximal and distal ash fall exposure from a range of eruptive styles. It also investigates the application of temporary external filters to minimise the ingestion of volcanic ash into generator housings. The results are used to inform recommendations on the likely impacts of ash to generators and the most effective type of mitigation, which maximises filtration whilst maintaining generator performance. Control tests recorded high particle concentrations (~0.006 mg/m3) which indicate substantial ash contamination is possible. Multiple factors were considered to determine the best mitigation measure including the lowest particle concentration, highest air speed and the ease with which the measure could be fitted. The study found material filtration to be the most effective measure; however as the quality of filtration increased, the air speed was reduced and thus so was the volume of air available to the generator engine. Therefore, the type of filtration required is dependent the ash fall intensity. The study also found that a deflection hood is an effective mitigation measure; maintaining airspeed while reducing particle concentrations within the generator. This research informs risk management strategies for critical infrastructure organisations to reduce the risk of generator disruption during volcanic ash falls.

In order to prepare for the next in situ missions to Mars (MSL-2011 and ExoMars-2018), the objective of mythesis is to create a collection of relevant analogue rocks and minerals for calibrating and testing future (and existing) space flight instruments, in accordance with the geology of Mars. They were characterized using standard laboratory instrumentation (optical microscopy, Raman, IR, XRD, SEM, electron microprobe and ICP-MS), as well as by flight instrumentation in development (Mössbauer MIMOSII, ExoMars Raman and IR (MicrOmega) spectrometers). All the samples are described in an online database in the following web site: www.isar.cnrs-orleans.fr. A part of this thesis is dedicated to the development of a cathodoluminescence (CL) instrument that could potentially be adapted for space flight. Study of alteration processes of basalts on Earth that show some similarities to surface and subsurface processes occurring on Mars may help understand and interpret martian features. Therefore, to complete the collection, samples of hydrothermal and acidic weathered basalts were collected from the Skouriotissa mine in Cyprus. The mineralogical evolution of the basalt through different alteration facies was studied. Because terrestrial basalts are poorer in Fe and Mg than martian basalts, I synthesized two artificial martian basalts. The two artificial basalts are different in terms of cooling rate (~110°C/h and drop-quenched, >1200°C/h). Interestingly, the more slowly-cooled sample exhibits a spinifex texture, similar to that of komatiites. If similar basalts occur on Mars, such rocks when altered by aqueous processes may have astrobiological implications.

Volatile trace metals are variably enriched in volcanic gases. Metal concentrations in sub-aerially erupted magmas are also depleted in many of these metals. The causes of variable metal enrichment in volcanic gasses, however, remain enigmatic. The objective of this work is to place experimental constraints on kinetic and thermodynamic factors that influence the concentrations of trace metals in volcanic gases. To measure metal mobility in silicate melts, Pt crucibles packed with metal doped glasses of broadly basaltic composition were equilibrated with air and mixed gases at atmospheric pressure. The metals in the melt diffused to the gas/melt interface where they were released as a volatile species. The experiments produced concentration-distance profiles from which diffusivity was derived. Experiments were also conducted in a piston-cylinder apparatus at 1 GPa pressure. In these experiments, melts were equilibrated with Cl-bearing fluids at high temperature and pressure. At equilibrium, trace metals partitioned between the melt and fluid phase as a function of temperature and fluid composition. The diffusivity of Re in melts of natural basalt, andesite and a synthetic composition in the CaO-MgO-Al2O3-SiO2 (CMAS) system has been investigated at 0.1 MPa and 1250-1350C over a range of fO2 conditions from log fO2 = -10 to –0.68. Re diffusivity in natural basalt at 1300C in air is logDRe = -7.2  0.3 cm2/sec and increases to logDRe = -6.6 0.3 cm2/sec when trace amounts of Cl were added to the starting material. At fO2 conditions below the nickel-nickel oxide (NNO) buffer Re diffusivity decreases to logDRereducing = -7.60.2 cm2/sec and to logDReandesite = -8.4  0.2 cm2/sec in andesite melt. Cd, Re, Tl, Pb, Sb and Te diffusivity in CMAS and Na2O-MgO-Al2O3-SiO2 (NMAS) melts were also determined at 0.1 MPa and 1200-1350C. In the CMAS composition at 1300C, the fastest diffusing element was Cd having a logDCd = -6.5  0.2. The slowest element was Re with logDRe = -7.5  0.3. Diffusivities of Sb, Te, Pb and Tl have intermediate values where logDSb = -7.1  0.1, logDTe = -7.2  0.3, logDPb = -7.1  0.2, logDTl = -7.0  0.2 cm2/sec. In the NMAS composition, logDRe = -6.5  0.2, logDSb = -6.0  0.2, logDPb = -6.1  0.1, logDTl = -5.8  0.2 cm2/sec. Fluid/melt partition coefficients ( ) of Re, Mo, W, Tl and Pb between fluid (H2O + Cl) and a haplobasaltic melt in the CMAS system were measured between 1200 and 1400°C at 1 GPa and fluid chlorine molarities from 7.7 to 27 mol/L. At 1300°C and fluid molarity of 7.7 mol/L, = 9.8±1.8, = 11.8±1.6, = 3.7±1.6, = 4.5±1.4 and = 2.4 ±1.8. Both Mo and Re were shown to partition most strongly into the fluid at all temperatures and fluid chlorinities. Differences in diffusivity of volatile heavy metal ions to a lead to significant fractionation between these metals in magmas during degassing. Given the observed differences in Cd and Re diffusivities, an increase in the normalized Cd/Re ratio in the gas phase with increasing bubble growth rate is predicted. Monitoring of the Cd/Re ratios in aerosols from degassing volcanoes may provide a tool for predicting volcanic eruption. Modeling of Re using the values measured here support the contention that subaerial degassing is the cause of lower Re concentrations in arc-type and ocean island basalts compared to mid-ocean ridge basalts. The model results were also compared with emanation coefficients for trace metals from natural volcanoes. The magnitudes of the modeled Re/Tl and Re/Pb in fluids at 1300C and the lowest fluid chlorinities were less than that observed from their emanation coefficients. Re and Pb are more sensitive to fluid chlorinity than Tl. The ratios of Re/Tl and Re/Pb expected from emanation coefficients are closely matched if partitioning values for experiments having fluid chlorinities of ~16-20 MCl at 1300C are used.

Beypazari Granitoid is a low temperature and shallow-seated batholite intruded the Tepek&ouml / y metamorphic rocks of the Central Sakarya Terrane. Composition of the granitoid varies from granite to diorite. The granitoid is unconformably overlain by Palaeocene and Eocene rock units. Thus the age is probably Late Cretaceous. The Beypazari Granitoid comprises mafic microgranular enclaves. The granitoid mainly consists of quartz, plagioclase, orthoclase and minor amphibole, biotite, chlorite, zircon, sphene, apatite, and opaque minerals. Plagioclase shows sericitation whereas biotite and hornblende, chloritization. Holocrystalline and hypidiomorphic are characteristic textures of the granitoid. Geochemically, the Beypazari Granitoid is calc-alkaline, metaluminous and I-type. REE data indicate that it may have been generated from a source similar to the upper continental crust. The trace element data of the Beypazari Granitoid suggest a volcanic arc tectonic setting. The possible mechanism of Beypazari granitoid is the northdipping subduction of Neo-Tethyan northern branch under Sakarya continent during Late Cretaceous. The Beypazari Granitoid may be related with Galatean volcanic arc granitoids.

Thesis (Ph. D.)--University of Hawaii at Manoa, 1995. / Includes bibliographical references (leaves 556-580). / Microfiche. / 2 v. (xv, 580 leaves, bound) ill., maps, col. photos. 29 cm

Yucca Mountain was designated as the proposed high-level radioactive waste repository by the U.S. Government in 1987. The proposed repository design requires high safety for a long maintenance period of 10,000 years. To satisfy this requirement, evaluation of the influence of earthquakes on the repository is necessary. Prediction of earthquake-induced ground motions around the repository requires knowledge of the dynamic properties of the geologic materials around the repository. The main geologic materials in the vicinity of Yucca Mountain are tuffs (ignimbrites) which are formed by the deposition of volcanic ash mixed with erupted volcanic gas, water vapor and pyroclastic material. Two types of dynamic tests, (1) the free-free, unconfined, resonant column and direct arrival test (freefree URC test) and (2) the fixed-free resonant column and torsional shear test (fixed-free RCTS test), were used to measure the dynamic properties of tuffs. The emphasis in this dynamic testing was evaluation of shear modulus (G) and material damping ratio (D) of the tuffs in the small-strain (linear) and mildly nonlinear (to strains of about 0.02 %) ranges. To evaluate the influence of various parameters on G and D of tuffs, correlations with other features such as total unit weight, porosity and stratigraphic unit were performed and general relationships between them are proposed. In addition, an unconfined, slow-cyclic torsional shear (CTS) device was developed and used to measure the cyclic shear properties of the tuffs from Yucca Mountain at larger strain amplitudes than possible in the fixed-free RCTS tests. Additionally, the CTS device was also used to determine the shear failure strength of the tuffs. By combining the cyclic shear properties of the tuffs from the CTS tests and the dynamic properties of the tuffs from the fixed-free RCTS tests, complete dynamic property curves from small-strain to failure strain were evaluated.

Mémoire (M.Sc.T.)-- Université du Québec à Chicoutimi, 1991. / Bibliogr.: f. 83-86. Document électronique également accessible en format PDF. CaQCU

Mémoire (M.Sc.T.)--Université du Québec à Chicoutimi, 1991. / Document électronique également accessible en format PDF. CaQCU

Mémoire (M.Sc.T.)-- Université du Québec à Chicoutimi, 1991. / "Mémoire présenté en vue de l'obtention de la maîtrise en sciences de la terre" CaQCU Bibliogr.: f. 166-171. Document électronique également accessible en format PDF. CaQCU

Thesis (M.S.)--Ohio University, November, 2003. / Includes bibliographical references (p. 73-77).