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Performance-based earthquake engineering is an emerging field of study that complements the prescriptive methods that the design codes provide to ensure adequate seismic performance of structures. Accounting for uncertainties in the performance assessments forms an important component in this area. In this context, the present study focuses on two broad themes; first, treatment of uncertainties and the application of the first-order reliability method (FORM) in finite-element reliability analysis, and second, the seismic risk assessment of reinforced concrete structures for performance states such as, collapse and monetary loss. In the first area, the uncertainties arising from inherent randomness (“aleatory uncertainty”) and due to the lack of knowledge (“epistemic uncertainty”) are identified. A framework for the separation of these uncertainties is proposed. Following this, the applicability of FORM to the linear and nonlinear finite-element structural models under static and dynamic loading is investigated. The case studies indicate that FORM is applicable for linear and nonlinear static problems. Strategies are proposed to circumvent and remedy potential challenges to FORM. In the case of dynamic problems, the application of FORM is studied with an emphasis on cumulative response measures. The limit-state surface is shown to have a closed and nonlinear geometric shape. Solution methods are proposed to obtain probability bounds based on the FORM results. In the application-oriented second area of research, at first, the probability of collapse of a reinforced concrete frame is assessed with nonlinear static analysis. By modelling the post-failure behaviour of individual structural members, the global response of the structure is estimated beyond the component failures. The final application is the probabilistic assessment of monetary loss for a high-rise shear wall building due to the seismic hazard in the Cascadia subduction zone. A 3-dimensional finite-element model of the structure with nonlinear material models is subjected to stochastic ground motions in the reliability analysis. The parameters for the stochastic ground motion model are developed for Vancouver, Canada. Monetary losses due to the damage of structural and non-structural components are included.

Avalanches pose a significant natural hazard in many parts of the world. Worldwide the hazard is being managed in a number of new and traditional methods. In New Zealand, the Milford Road, Fiordland, has a significant avalanche problem which has been managed by the Transit New Zealand Milford Road Avalanche Programme since 1984. This avalanche programme has generated a database of all avalanche occurrences and associated meteorological parameters for the time period 1985 to 2002. Elsewhere around the world, similar and more extensive data sets have been used to examine a wide variety of aspects in relation to the snow cover, avalanching and avalanche hazard. The availability of the Milford Road database has provided the opportunity use new and traditional approaches to examine many aspects of avalanching including; the trends in and relationships with the snow and avalanche regime, evaluation of the avalanche hazard, statistical forecasting of avalanches and the visualisation of avalanche occurrence information in a GIS. Statistical and graphical examination of the inter-annual variation in the snow and avalanche regime revealed relationships between the snow depth, avalanche occurrences and atmospheric circulation similar to those found elsewhere around the world, but not previously examined in New Zealand. Furthermore, the analysis resulted in strong correlations despite using a database significantly shorter than those used elsewhere. Atmospheric circulation types that bring strong winds and precipitation were found to be highly significantly correlated with avalanche occurrences and snow depth. Avalanche occurrences were more highly correlated with atmospheric circulation than snow depth was, reflecting the strong maritime avalanche climate. Risk evaluation was undertaken using two approaches, the avalanche hazard index (AHI) and the probability of death to individuals (PDI) method. The present avalanche risk was compared to a theoretically uncontrolled avalanche regime, using 2002 traffic volumes for AHI and PDI. The AHI analysis highlighted the reduction in the AHI resulting from the control programme, and the significantly lower AHI when compared to Rogers Pass, B.C., Canada. The PDI analysis using equations modified to allow for a range of consequences indicated that the Milford Road is similar in risk to roads in Switzerland, but is far more accessible, with fewer closed days. A new equation for PDI, which accounted for waiting traffic was derived, and suggested that the calculated risk was high and unacceptable compared to standards applied to other hazards. Statistical forecasting using classification tree analysis has been successfully applied to avalanche forecasting in other climatic settings. This study has applied an extension to this technique through 10-fold cross validation to permit classification of an avalanche day in this direct action maritime climate. Using varying misclassification costs two classification trees were generated. The tree that used only wind speed and wind speed and precipitation combined in a temperature sensitive wind drift parameter obtained an overall accuracy of 78%, with correct prediction for an avalanche day at 86%. These predictor variables are considered to be the fundamental controls on avalanche forecasting in this climate, and coincide with important variables inferred from the atmospheric circulation analysis. Following the investigation of various methods for the creation of a high resolution digital elevation model (DEM), a GIS was used for the visualisation and examination of avalanche occurrences. Similar to other studies, qualitative and quantitative analysis of the spatial distribution in terms of aspect of avalanche occurrences was undertaken using the GIS. Colour coding of occurrences highlighted the influence of two storm directions, while an excess ratio showed the clear influence of aspect on avalanche occurrences in relation to two dominant storm directions, avalanche size and avalanche paths. Furthermore, the GIS has many applications for operational forecasting, teaching and the maintenance of institutional memory for the avalanche programme.

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.

Thesis (Ph. D.)--University of Nevada, Reno, 2007. / "May, 2007." Includes bibliographical references (leaves 84-95). Online version available on the World Wide Web.

Thesis (Ph. D.)--University of Nevada, Reno, 2007. / "May, 2007." Includes bibliographical references. Online version available on the World Wide Web.

Thesis (M.Sc. Earth and Ocean Science)--University of Waikato, 2008. / Title from PDF cover (viewed August 26, 2008) Includes bibliographical references (p. 169-177)

Thesis (M.A.)--Ohio University, August, 2008. / Title from PDF t.p. Includes bibliographical references.

Thesis (M.S.)--University of Wyoming, 2007. / Title from PDF title page (viewed on Nov. 13, 2008). Includes bibliographical references (p. 210-213).

Thesis (M. Sc.)--University of Canterbury, 2008. / Typescript (photocopy). Three folded leaves of ill. in pocket. Includes bibliographical references (leaves 175-185). Also available via the World Wide Web.