The purpose of this research is to better understand how residents of communities located on the flanks of Kilauea, Hawai'i view the hazards associated with volcanic events taking into account hazard proximity, cultural beliefs, municipal trust, and evacuation planning. The study was conducted in the lower Puna district, an area with a rapidly growing population but limited infrastructure. Data were collected though a questionnaire survey undertaken at venues throughout the district, including grocery markets, bakeries, farmers markets, the public pool, and other gathering places. Overall, the results indicated that people understand the natural hazards of the place but are generally not concerned about the potential impacts of these hazards on their livelihoods; few could determine whether or not they lived in a lava zone, the impacts on health, and the need for evacuation planning. Cultural considerations appear to play major role and many residents believe that Madam Pele, Goddess of Fire, has a stake in the events of Kilauea. Both hazard understanding and cultural belief systems varied by gender, age, income, and education. When compared to findings from earlier studies within the lower Puna district, it was noted that opinions have shifted over time and that belief in Pele had strengthened. This study demonstrated that understanding the opinions and patterns of belief within communities must be ongoing and municipal planning must be altered over time to accommodate evolving needs and beliefs of a community to obtain optimum community support.

<p>The focus of this work is to use geologic and geophysical methods to better understand the faults and fracture systems at Puna, in southeastern Hawaii, and southern Montserrat, in the Lesser Antilles. The particular interest is understanding and locating the deep fracture networks that are necessary for fluid circulation in hydrothermal systems. The dissertation first presents a study in which identification of large scale faulting places Montserrat into a tectonic context. Then follow studies of Puna and Montserrat that focus on faults and fractures of the deep hydrothermal systems.</p><p>The first chapter consists of the results of the SEA-CALIPSO experiment seismic reflection data, recorded on a 48 channel streamer with the active source as a 2600 in3 airgun. This chapter discusses volcaniclastic debris fans off the east coast of Montserrat and faults off the west coast. The work places Montserrat in a transtensional environment (influenced by oblique subduction) as well as in a complex local stress regime. One conclusion is that the stress regime is inconsistent with the larger arc due to the influence of local magmatism and stress.</p><p>The second chapter is a seismic study of the Puna hydrothermal system (PHS) along the Kilauea Lower East Rift Zone. The PHS occurs at a left step in the rift, where a fracture network has been formed between fault segments. It is a productive geothermal field, extracting steam and reinjecting cooled, condensed fluids. A network of eight borehole seismometers recorded >6000 earthquakes. Most of the earthquakes are very small (< M.2), and shallow (1-3 km depth), likely the result of hydrothermal fluid reinjection. Deeper earthquakes occur along the rift as well as along the south-dipping fault plane that originates from the rift zone.</p><p>Seismic methods applied to the PHS data set, after the initial recording, picking, and locating earthquakes, include a tomographic inversion of the P-wave first arrival data. This model indicates a high seismic velocity under the field that is thought to be an intrusion and the heat source of the hydrothermal system. A shear wave splitting study suggested the PHS fracture system is largely oriented rift-parallel with some orthogonal fractures. Shear wave splitting data also were used in a tomographic inversion for fracture density. The fracture density is high in the PHS, which indicates high permeability and potential for extensive fluid circulation. This has been confirmed by high fluid flow and energy generation. The high fracture density is consistent with the interpretation of a transfer zone between the rift segments where a fracture mesh would be expected. In Puna the transfer zone is a relay ramp.</p><p>The results from the PHS are used as an example to examine the proposed hydrothermal system at St. George's Hill, Montserrat. In southern Montserrat, hot springs and fumaroles suggest a deep hydrothermal system heated by local magmatism. A magnetotelluric study obtained resistivity data that suggest focused alteration under southeastern Montserrat that is likely to be along fault segments. Several faults intersect under SGH, making it the probable center of the hydrothermal system. At Puna, and also Krafla, Iceland, where faults interact is an area of increased permeability, acting as a model to be applied to southern Montserrat. The conclusion is that in both Puna and Montserrat large faults interact to produce local areas of stress transfer that lead to fracturing and permeable networks; these networks allow for high-temperature hydrothermal circulation.</p> / Dissertation

Connaître mieux l'intérieur de la Terre nécessite d'améliorer les méthodes d'investigation géophysique. Cette thèse s'est interessée à une classe importante de ces méthodes : la tomographie sismique. La tomographie sismique classique utilise des temps d'arrivée d'ondes sismiques, dont la précision dépend du pas d'échantillonnage et du pointé de l'onde. Lorsque les trains d'onde sont similaires, c'est-à-dire lorsque les sources et/ ou les récepteurs sont proches, on peut calculer, avec une précision inférieure au pas d'échantillonnage, le décalage temporel entre les trains d'ondes. Cette thèse a eu pour objectif l'utilisation de telles données en tomographie sismique. Utiliser pleinement la précision de ces données a nécessité une revisite complète des algorithmes de tomographie, tant du point de vue du problème direct que du point de vue du problème inverse. Une solution robuste et précise a été trouvée au problème direct (calcul du temps de propagation des ondes dans un milieu hétérogène). Une attention particulière a été portée au problème inverse : une approche Tarantola-Valette a été utilisée, de façon à trouver le modèle de norme minimale qui ajuste les données. La minimisation de cette norme est obtenue par l'introduction d 'une fonction de corrélation des paramètres du modèle, dont la longueur et l'amplitude sont ajustées en suivant une procédure d'optimisation. De cette façon, toute fluctuation du modèle est contrainte par les données. L'algorithme mis au point a été utilisé avec des données provenant de séismes du volcan Kilauea (Hawaii) enregistrés par le réseau local USGS-HVO (50 stations). Il a permis de retrouver le modèle de vitesse à deux échelles : (1) une échelle régionale, où l'on retrouve le système magmatique profond, sous les calderas et les rifts du Mauna Loa et du Kilauea; le modèle trouvé permet d'expliquer les déformations mises en évidence dans la croûte océanique, la distribution confinée de la sismicité et les déformations intenses du flanc Sud du Kilauea; (2) une échelle locale, où l'on met en évidence un conduit magmatique sub-vertical sous la caldera et le rift Est du Kilauea, indétectable avec d'autres données. Cette méthode, précise, permet de choisir un modèle unique et stable à l'aide un critère d'optimisation objectif.

Metallic bronze-Co-Ag alloys ranging from1-90 µm have been discovered in bomb and lava vesicles from the mafic volcanoes of Kilauea in Hawaii and Vesuvius, Stromboli and Etna in Italy. It is inferred that the metals for these alloys were transported (in part) as chloride complexes, and that the metal ratios in the alloys may be a function of S/Cl. Alloy compositions in each system are extremely heterogeneous with Co concentrations from 1% to 94%, Cu from 2% to 89%, Sn from 1% to 22% and Ag from 0.5% to 42%. Maximum abundances (in wt%) of other trace or minor elements are, Fe (3.0), Zn (0.11), As (0.50), Pd (0.05), Pt (0.05), Au (0.05), Hg (0.10) and Pb (.13) Spot analyses and element maps of alloy grains reveal that three major exsolved components exist. They are bronze, Co, and Ag. Kilauean alloys are dominantly Cu-Sn (bronze) with little Co and Ag while a systematic decrease in the bronze component and an increase in Co occurs in grains from Stromboli to Etna to Vesuvius. Element maps show a covariance of Cu and Sn while Co and Ag concentrations vary independently. Element maps of the alloys also reveal that chlorides are occasionally present in the same vesicles as the alloys. Sulphur content of the metal alloys rarely exceed about 0.4 wt%. Electron back-scatter diffraction (EBSD) was employed for lattice characterization of the exsolved phases and shows a FCC structure for the Cu-Sn section of the alloys. Cu-Sn alloys high in Sn are successfully indexed using the Cu6Sn5 pattern (hexagonal), even though the Sn:Cu ratio of our alloys is considerably lower than 5:6. Cu-Sn alloys containing significant subequal amounts of Co and Fe (≈5 wt% each) indexes as body-centered cubic (BCC). The presence of alloys suggests metal transport as complexes in a vapor phase before being reduced to native metals. Our current model for the origin of the alloys suggests that the metals are transported to vesicles as chlorides and then deposited as sulfides and/or native metals. Oxidation and removal of most of the S then occurs. This data suggests that in some circumstances Cu-Sn-Co and Ag are readily partitioned into escaping magmatic volatiles during quenching of mafic magma. Further examination into vesicle-hosted alloys may confirm that the ratio of Cu, Ag, Au, Zn, and Pb in vesicles reflects the ratio of available metals present in the magma and in subsequent ore deposits.

The opportunistic environmental microbes, non-tuberculous Mycobacterium (NTM), pose an increasing risk of disease and death in both immunodeficient and immunocompetent individuals in the USA and across the world. NTM lung disease is particularly prevalent in Hawaii, although the modes of NTM acquisition and transport in Hawaii are not fully understood. This study evaluated 149 soil and 50 water samples across the Hawaiian Islands to determine geochemical factors controlling NTM. Non-metric multidimensional scaling (NMDS) and principal component analyses (PCA) of modern soils show variables such as Total Organic Carbon (TOC), pH, P, mafic silicate minerals, and Pb seem to control NTM presence and transition metals and oxides such as TiO2, Zr, and Nb seem to control the absence perhaps due to toxicity. Logistic regression modeling coupled with Kolmogorov-Smirnov testing supported that TOC and P could be used to explain the probability of NTM presence in modern soils. Kolmogorov-Smirnov, non-metric multidimensional scaling, and principal components analysis results suggest poor predictability of NTM presence in soils when evaluating mineralogy alone. The same statistical methods indicated that transition metals appeared to control NTM presence in stream water and major cations and anions seemed to control NTM absence. However, additional bacterial stream data is needed to strengthen this finding. Additionally, an Oahu source water assessment and protection groundwater model was refined by including stream discharge data, including losses to the aquifer. NTM inhabits many environmental niches, although little is understood regarding the transport of NTM from the environment to indoor plumbing. However, transport from surface water to water-supply aquifers is likely important. This study analyzes groundwater flow from stream losses as a mechanism of NTM transport to water supplies. An updated MODFLOW groundwater model was developed for the north-east Oahu, Waimea River drainage. Results show hundreds of meters of lateral and tens of meters of vertical transport of NTM in 1-3 months. Additionally, geochemical modeling with Geochemist’s Workbench showed Fe oxy/hydroxides oversaturated in 100% of streams. Fe oxy/hydroxide affixed to NTM would potentially satisfy NTM’s preference for attachment and allow for colloidal transport through the aquifer.

Graduation date: 2005