Thesis (Ph. D.)--University of Texas at El Paso, 2009. / Title from title screen. Vita. CD-ROM. Includes bibliographical references. Also available online.

Thesis (Ph. D.)--Oregon State University, 1995. / System requirements for computer disk: Macintosh. Typescript (photocopy) Includes bibliographical references (leaves 181-184). Also available online.

Made available in DSpace on 2016-05-17T16:51:45Z (GMT). No. of bitstreams: 0 Previous issue date: 2015-10-30. Added 1 bitstream(s) on 2016-05-17T16:55:33Z : No. of bitstreams: 1 000864623.pdf: 7761369 bytes, checksum: 6fac5bc2304624dd1699245d98931aae (MD5) / Os traquitos e dacitos do tipo Chapecó (ATC) e dacitos e riolitos do tipo Palmas (ATP), de idade cretácica, compõem 2.5% dos ~ 800.000 km3 de lavas da Província Magmática do Paraná (PMP) geradas anteriormente à quebra de Gondwana... / The Cretaceous Chapecó trachydacites-dacites (ATC) and Palmas dacites-rhyolites (ATP) make up 2.5% of the ~ 800.000 km3 of lava of the Paraná Magmatic Province (PMP), prior to Gondwana breakup...

Orientadores: Carlos Roberto de Souza Filho, Clive Matthew Martin Oppenheimer / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Geociências / Made available in DSpace on 2018-08-22T23:47:32Z (GMT). No. of bitstreams: 1 Murphy_SamuelWilliam_D.pdf: 5456096 bytes, checksum: 83ba771a9ac314dbabebef173f7abdf1 (MD5) Previous issue date: 2013 / Resumo: O monitoramento de vulcões é necessário para a mitigação do perigo que apresentam à sociedade. Esse monitoramento pode ser feito em uma escala global através de satélites. Foi com essa finalidade que este doutorado visou desenvolver metodologias para o monitoramento das atividades termais dos vulcões observados do espaço. Chegou-se a isso através do uso de uma variedade de sensores infravermelhos orbitais. Foi utilizado o sensor Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), que oferece imagens de moderada a alta resolução espacial (30 - 90 m) no infravermelho das ondas curtas (SWIR) e infravermelho termal (TIR), a fim de caracterizar o tamanho e a intensidade das anomalias termais. As bandas do TIR do ASTER conseguiram detectar anomalias sutis, o que permitiu a observação de novos precursores termais antes das erupções. O Moderate Resolution Imaging Spectroradiometer (MODIS) oferece imagens de alta resolução temporal (i.e. cobertura global diária), por isto foi utilizado para investigar atividade termal através do tempo. A análise de wavelets foi utilizada para quantificar os períodos de oscilação de tal atividade. Hyperion é um espectroradiômetro imageador e foi utilizado para demonstrar uma nova metodologia para calcular fluxo radiante de alvos termalmente heterogêneos (i.e. vulcões). Essas metodologias utilizam as melhores resoluções de cada um dos sensors: espacial (ASTER), temporal (MODIS), espectral (Hyperion) pode ser automaticamente executadas em escala global. Essa tese visa, portanto apresentar uma fundação sólida onde futuros sistemas de monitoramento de vulcões podem ser baseados / Abstract: Volcanoes need to be monitored to mitigate the risk that they pose to society. This can be done on a global scale using satellite sensors. The goal of this doctorate was to develop methods for the monitoring of volcanic thermal activity from space. This was achieved through the use of a variety of orbital infrared sensors. The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), which offers moderate to high spatial resolution imagery (30 - 90 m) in the short-wave infrared (SWIR) and thermal infrared (TIR), was used to characterize the size and intensity of thermal anomalies. Its TIR channels were capable of detecting subtle thermal anomalies. This permitted the observation of new thermal precursors to eruptive events. The Moderate Resolution Imaging Spectroradiometer (MODIS) offers high temporal resolution imagery (i.e. daily global coverage). It was therefore used to investigate thermal activity through time. Wavelet analysis was used to quantify the time period over which such activity oscillates. Hyperion is an orbiting imaging spectrometer. It was used to demonstrate a new method for calculating radiant flux from thermally heterogeneous targets (i.e. such as volcanoes). These methods utilized the strengths of each sensor system, i.e. high spatial, temporal or spectral resolution. They all improve the ability to detect and/or quantify thermal anomalies from space and can be executed in an automated global basis. This thesis therefore presents a solid foundation on which the next generation global volcano monitoring system can be based / Doutorado / Geologia e Recursos Naturais / Doutor em Ciências

The Valle del Bove is a horse-shoe shaped depression, 8km long and 5km wide, cut into the eastern flanks of Mount Etna, Sicily. In the southern cliff walls there are exposed the lavas and pyroclastics erupted by six ancient centres of activity which existed in the vicinity of the site now occupied by the Valle del Bove. The majority of these volcanics originated at a centre, Trifoglietto II, which occupied a position on the site of the southern Valle del Bove, and which was still erupting lavas at 25,000 ys BP. A reconstruction of the topography which previously existed within the Valle del Bove, is accomplished by extrapolating preserved contours on the northern and southern walls of the depression. Reconstruction of the Trifoglietto II centre shows that its summit was probably between 2500m and 2600m above present sea-level, and that it consisted of a cone constructed predominantly from pyroclastic materials, overlain on its southern and eastern flanks by lavas. A stratigraphy is constructed for the southern wall. The Trifoglietto II lavas rest unconformably upon the eroded remnants of an older centre, and are themselves overlain by the products of younger centres. All the lavas exposed in the southern wall are of alkalic affinity, and comprise a trachybasaltic suite ranging from hawaiite to benmoreite. Variation in the chemistry of most of the lavas can be explained by their differentiation at high levels in the crust, from a more basic magma of alkalibasalt/hawaiite composition. Chemical variation in the Trifoglietto II lavas, however, can best be explained as a result of generation by the partial melting of garnet-peridotite material at upper mantle depths and pressures. A study has been made of the numerous dykes exposed in the walls of the Valle del Bove., the alignments of which parallel trends which are important on Etna at the present time. It is proposed that the Valle del Bove was formed by phreatic or phreato-magmatic eruptions which destroyed the Trifoglietto II centre, some 15-17,000 ys BP, following magmatic extinction at the centre. The eruptions produced lahars which are evident to the east of the depression, and extensive air-fall ashes. Subsequent enlargement of the Valle del Bove was accomplished by fluvial erosion.

Volcanic arcs are the primary seat of subaerial volcanism and where continental crust is created. Since the advent of plate tectonics theory in the last half century, many of the processes that govern arc magmatism have been described in detail. However, understanding the development and eruption of upper crustal magma reservoirs remains a fundamental challenge. Here we develop and implement new geochemical approaches, and combine our results with those from other disciplines, to explore the location, formation, and eruption of upper crustal magma reservoirs, with the ultimate goal of linking these processes to the underlying process of plate tectonics. Our study area is the central-eastern Aleutian arc, one of the most volcanically active regions on earth, where significant along-strike variability in subduction parameters, magma compositions, and volcanic activity exists. To advance understanding of magma reservoirs, it is essential to hone our tools for gauging magma depth. Melt inclusion analysis is the first in the toolbox for petrologists, but recent studies have raised questions about the accuracy of this approach. Vapor bubbles commonly form in melt inclusions after entrapment. These bubbles may sequester a substantial portion of the total volatile contents of the melt inclusion, which is problematic because depth estimates are based on melt volatile contents. In Chapter 1, we explore vapor bubble growth in melt inclusions by describing the processes, and their timescales, that lead to bubble growth and developing new methods to retrieve accurate depth estimates from melt inclusions. Our new methods have situational strengths. In concert, they enable extraction of reliable depth information, unlocking the true potential of melt inclusions to measure depth. With an improved understanding of melt inclusions, we next investigate eruption run-up. During run-up, crustal-scale magmatic systems can be activated, providing a unique opportunity to peer into their structure. In Chapter 2, our goal is to study eruption run-up and determine how magmas are stored in the months, days, and hours leading to volcanic eruption. As a case study, we investigate the 1999 eruption of Shishaldin volcano, of interest because the run-up was months, an unusually long duration, and, despite 43 million cubic meters of tephra ejected in the eruption, no eruption-related deformation was detected in satellite imagery. We develop a new approach for studying run-up that combines diffusion modeling, which gives information on the timing of magmatic processes preceding eruption, with melt inclusion analysis, which gives depth information. Results are combined with those from shear-wave splitting analysis and other geophysical methods. We identify a shallow magmatic system that existed prior to the run-up to the 1999 eruption. A substantial fraction of the magma that was erupted was delivered to the shallow reservoir ~50 days prior to the eruption. More broadly, our results indicate that open-system volcanoes, such as Shishaldin, may commonly have long run-up durations. Our work on run-up demonstrates the strength of the forensic approach for studying magma reservoirs, but it leads us to question what can be understood in real time. One powerful approach for understanding the state and location of magma reservoirs in real time is the study of volcanic gas emissions. However, interpretation of gas data is a major challenge. To improve our ability to use gas data to understand plumbing systems, and to investigate the shallow magmatic plumbing system of an open-vent volcano, we perform a melt inclusion study of the degassing system at Cleveland in Chapter 3. We focus on Cleveland volcano, one of the most active volcanoes in the US. We develop an empirical degassing model based on melt inclusion data. We use the degassing model to interpret gas composition and flux measurements at Cleveland. Our results indicate gas emissions are generated in a shallow, convecting magmatic system, which is consistent with geophysical observations. After detailing plumbing systems at Shishaldin and Cleveland, we investigate global trends in magma storage depth in Chapter 4. Geophysically imaged magma storage depths are mostly ~0-20 km depths. The reason for the dramatic variability is not well known. We compile geophysical estimates of magma storage depth and compare these data to magmatic water contents. The initial water content of magma is thought to exert a key control over magma storage depth because as magmas ascent, they degas water. Concurrently, melt viscosity increases and crystallization may be induced. Both these processes promote slowing of magma ascent. We find a strong correlation between magma storage depth and magmatic water contents at the 24 volcanoes that have estimates for both. A global compilation of magma storage depths at 97 volcanoes has a distinct mode at 6 ±3 km, which coincides very closely with the average depth at which arc magmas become water saturated (6 ±3 km) based on maximum water content estimates from a compilation of 77 volcanoes. Melt inclusions from the eastern-central Aleutians do not show evidence of degassing or diffusive loss of water, indicating that water content is a strong control over magma storage depth. The trend exists globally, despite a large range in potential upper crustal controls (thickness, age, stress state, etc.). In Chapter 5, we move deeper in the arc to understand the underlying processes of subduction and arc magma genesis. Slab depth in the central-eastern Aleutians varies from a near global minimum of 65 km in west (near Seguam) to a more common value of 100 km in the east (near Shishaldin). The cause for this variability is not well known. The thermal structure of the wedge is thought to play a key role in determining where mantle melting occurs, and subduction parameters (slab age, dip, velocity, etc.) exert first order controls on wedge thermal structure. Therefore, subduction parameters are likely to some extent modulate slab depth. However, the mantle-slab coupling depth also has a key influence on the thermal structure of the wedge. Therefore, the coupling depth must also play a role in determining slab depth. A potential third factor is the extent of lateral melt migration in the wedge. In the central-eastern Aleutians, variations in slab depth are reflected in variations in major, trace, and volatile elements. Chemical trends are most consistent with a shallow slab-mantle coupling depth of 50 km throughout the corridor. Results from slab top thermometry suggest that significant lateral variation is unlikely. We speculate that the change in slab depth across the corridor is likely a result of the significant decrease in trench fill sediment thickness moving east.

Cassini spacecraft images of Io obtained during its flyby of Jupiter in late 2000 and early 2001 were used to determine the lava composition and eruption style of three faint hotspots, Pillan, Wayland, and Loki. We found a maximum color temperature of 1130+/-289 K for Pillan and maximum color temperatures of 1297+/-289 K and 1387+/-287 K for Wayland and Loki, respectively. These temperatures are suggestive of basaltic lava. The temperatures with the best signal-to-noise ratios also suggested basaltic lava and were found to be 780+/-189 K, 1116+/-250 K, and 1017+/-177 K for Pillan, Wayland, and Loki, respectively. Pillan showed increased activity on the third eclipse day after being fairly constant for the first two days, suggesting increased fountaining or lava flow activity on the third day. The data also suggest that Pillan is surrounded by topography that blocked emission on day000 and caused a much more dramatic decrease in emission. Wayland's intensity decreased over the three eclipses, consistent with a cooling lava flow or decreasing eruption. However, rapid decreases in intensity over periods of 26 to 48 minutes could have resulted from the eruption of highly exposed lava, perhaps an open channel or fountain. The data also suggest Wayland may be in a depression surrounded by ridges that blocked part of the emission. Intensities at Loki over the course of the observation varied in both directions, and were consistent with previous determinations of an often quiescent lava lake with periods of active overturning and fountains.

No description available.

Thesis (Ph. D.)--University of Washington, 1999. / Vita. Includes bibliographical references (leaves 174-181).

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.