Understanding the dynamics of tsunamis from signatures in the landscape

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Embargoed until 2018-11-30
Copyright: Kain, Claire
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Abstract
The overarching aim of this research is to extend our understanding of the relationship between historic and prehistoric tsunami waves and the signatures they leave behind in the landscape. Previous sedimentary research has developed methods for identifying tsunami signatures and attempting to distinguish them from related processes, but has not generally provided detailed information about the events that created them. The methodological framework of this thesis contains two components: a global scale meta-data analysis of the relationships between tsunami deposit texture and environmental parameters, and regional/local scale field and laboratory based investigations of erosional and depositional signatures in the sedimentary record. A combination of techniques was applied to case studies in Indonesia and New Zealand. In Indonesia, GPR was used to study erosional tsunami signatures and measure coastal recovery processes in order to better interpret the completeness of preserved features. In New Zealand, historic and prehistoric tsunami deposits were identified, and their inundation extent, flow patterns and sediment source determined. Methods were drawn from sedimentology, geochemistry and mineralogy, geophysics and statistics. Results of the global scale meta-data analysis showed significant relationships between tsunami deposit form and climatic parameters, sediment density and degree of coastal protection. While these relationships have long been understood at a local level, this is the first work to attempt to quantify these patterns at a broader scale. At a regional scale, geochemical and mineralogical analyses successfully identified marine signatures and source material in anomalous deposits. Multivariate statistical analyses of these data allowed tsunami signatures to be separated from those of similar deposits. This approach prevented grain size variations from obscuring other signatures. Statistical analyses of MF and sedimentological data to reconstruct tsunami flow and basic dynamics had also not previously been attempted. Local scale results from Okains Bay, New Zealand, highlighted the importance of landscape geometry in controlling tsunami flow and demonstrated a case where inundation occurred entirely via the river channel. The findings of this thesis help to improve our understanding of tsunami signatures in the sedimentary record and have implications for the effective management of tsunami risk in the future.
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Author(s)
Kain, Claire
Supervisor(s)
Goff, James
Chague-Goff, Catherine
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Publication Year
2016
Resource Type
Thesis
Degree Type
PhD Doctorate
UNSW Faculty
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