Thesis (M.S.)--Oregon State University, 1983. / Typescript (photocopy). One map folded in pocket. Includes bibliographical references (leaves 107-110). Also available online.

Thesis (Ph. D.)--University of Washington, 2000. / Vita. Includes bibliographical references (leaves 136-142).

Thesis (Ph. D.)--Washington State University, December 2009. / Title from PDF title page (viewed on Dec. 15, 2009). "School of Earth and Environmental Sciences." Includes bibliographical references (p. 232-247).

published_or_final_version / Earth Sciences / Master / Master of Philosophy

No description available.

No description available.

No description available.

The term “blue-sky eruption” (BSE) can be used to describe eruptions which are unexpected or have no detected precursory activity. Case study analyses indicate that they have a diverse range of characteristics and magnitudes, providing both direct and indirect hazards and occur in both under-developed and developed countries. BSEs can be a result of physical triggers (e.g. the lack of physically detectable precursors or a lack of understanding of the eruption model of the volcano), social triggers (such as an inadequate monitoring network), or a combination of the two. As the science of eruption forecasting is still relatively young, and the variations between individual volcanoes and individual eruptions are so great, there is no effective general model and none should be applied in the absence of a site-specific model. Similarly, as methods vary between monitoring agencies, there are no monitoring benchmarks for effective BSE forecasting. However a combination of seismic and gas emission monitoring may be the most effective. The United States began a hazard and monitoring review of their volcanoes in 2005. While the general principles of their review would be beneficial in a monitoring review of New Zealand’s volcanoes, differences in styles of volcanism, geographic setting and activity levels mean changes would need to be review to fully appreciate the risk posed by New Zealand’s volcanoes. Similarly, the monitoring benchmarks provided in the U.S. review may not be fully applicable in New Zealand. While advances in technology may ultimately allow the effective forecasting of some BSEs, the immediate threat posed by unexpected eruptions means that effective management and mitigation measures may be the only tools currently at our disposal to reduce the risks from BSEs.

Volcanic eruptions are powerful, uncontrollable natural events which produce a number of hazards that can impact upon all aspects of society, including critical infrastructure. The most widespread and disruptive of these hazards is volcanic ashfall. Direct ashfall impacts, even minor, can cause multiple knock on effects throughout all critical infrastructure sectors leading to disruption of these services, on which society relies. However with appropriate volcanic risk management strategies, these impacts can be lessened. Electronic equipment, including laptop computers, are a common and vital component in all critical infrastructure sectors, field based volcanic research and wider society. Therefore, it is important to understand how laptops will function in volcanic environments. This thesis assesses the vulnerability of laptop computers to volcanic ash and gas hazards through field and laboratory based experimentation and the development of quantitative risk assessments metrics. Laboratory based ash vulnerability experiments were carried out in the Volcanic Ash Testing Facility, University of Canterbury, using a mass produced basalt ‘pseudo ash’, which is physically and chemically analogous to fresh volcanic ash. Each laptop was exposed to ash for 100 160 hours at fall rates of ~500 g/m² h. None of the ten laptops used sustained any permanent damage from volcanic ash, however, three shutdown temporarily due to overheating. This was because laptops only contain a few small ventilation holes which prevent large quantities of ash from entering the laptops. However, ash contamination reduced functionality of keyboards, CD drives and some cooling fans as these are open to the environment or located close to ventilation holes. Wet ash, known to cause short circuits of electrical equipment, was not able to enter the laptops because it is less mobile than dry ash. Functionality was retained with the use of simple mitigation techniques such as placing laptops inside heavy duty polyethylene bags. Volcanic gas vulnerability experiments were undertaken at White Island, New Zealand. Three laptops were exposed to high concentrations of volcanic gases for ~5 hours. None however, sustained any permanent damage, due to the limited quantity of gas that could enter the laptop, although metal components on the outside of the laptop sustained minor corrosion.

This study assesses the geological constraints on fluid flow within the main crater of Whakaari volcano (White Island) which is located in the Bay of Plenty, New Zealand. A review of the volcanological and morphological history, field mapping, and permeability experiments were used to propose a model for single-state (gas or liquid water) fluid flow in the volcano. Three structural scales were of most importance: (a) the elongate main crater (1.2 km by 0.5 km); which contains (b) three subcraters (~300-500 m in diameter); and (c) >14 historic eruption craters and crater complexes (30-300 m in diameter). A large (2.1x10⁸ m³) sector collapse formed the basic morphology and structure of the amphitheatre-like main crater ≤3.4 ka. Hot fluids are released from magma at ~1–2 km depth and circulated within a conduit-hosted volcano-hydrothermal system. The collapse event was likely to have removed low permeability cone lavas, significantly increasing meteoric water collection and lateral seawater infiltration within high permeability main crater fill above the magma conduit. It is proposed that this caused a susceptibility to ‘wet’ (i.e. phreatic and phreatomagmatic) eruptions which possibly formed three prehistoric subcraters and has been demonstrated in the last ~200 years of available historic record. The permeability of the remaining in-situ cone lavas is controlled by micro- (<1 mm) and macro- (>1 mm) cracks but despite these cracks, the cone lavas’ permeability is still sufficiently low to focus rising magmatic fluid flow through main crater fill. Low-to-high permeability lithified tuffs are inferred to fill the main crater at depth. Low permeability fine ash tuffs generally restrict vertical fluid flow put permit it when vertical trains of vesicles are present. Atmospheric steam and gas pluming is accommodated by a permeable zone of repeated and overlapping historic eruption crater-related discontinuities that extend to >250 m depth through highly permeable unlithified main crater fill in the west. It is likely to be this material into which the seawater infiltrates from the east. Throughout the main crater, fluid flow is focussed at subcrater margins due to steeply-dipping discontinuities between low permeability lava and low-to-high permeability crater fill deposits. The variable permeabilities of crater fill deposits are due to age-related factors of hydrothermal alteration, reworking/sorting, consolidation, and pore mineralisation. At shallow levels (<100 m depth), vertical fluid flow is diverted to historic eruption crater margins by very low permeability clay (reworked and altered tephra). High permeability coarse ash tuffs, Fe-rich lapilli tuffs, and surficial solfatara deposits do not appear to have much effect on the overall fluid flow system. The results of this study show that, within active volcanic craters, the spatial distributions of variably permeable lithologies are often related to discontinuous cratering structures. Together, these are significant geological constraints on fluid flow. Morphological changes to crater structure can directly impact the groundwater regime above the magma conduit and may strongly influence the occurrence of wet versus dry eruptions. This process is possibly a significant control on eruptive behaviour at volcanoes with similar fluid flow systems worldwide.