Browsing by Author "Courtney, C"

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    Multi-proxy evidence for trans-Pacific tsunamis in the Hawai'ian Islands
    (Elsevier, 2012-03-01) Chagué-Goff, C; Goff, JR; Nichol, SL; Dudley, W; Zawadzki, A; Bennett, JW; Mooney, SD; Fierro, D; Heijnis, H; Dominey-Howes, D; Courtney, C
    The origin of two sand layers buried in Pololū wetland, on the northeast coast of the island of Hawai'i, was investigated using a multi-proxy approach, including radiometric dating, sedimentology, geochemistry, micropalaeontology, palynology and historical records. Based on 210Pb, 137Cs and pollen data, the lower sand unit extending 250 to 350 m inland is attributed to the 1946 Aleutian tsunami, while the upper sand unit was laid down by the 1957 Aleutian tsunami. Chronological information does not appear to support any link between these deposits and historical storm events. Furthermore, sedimentological, geochemical, diatom and pollen results suggest deposition of marine and near-beach sediments under high energy conditions typically associated with tsunami inundation. This work presents the first conclusive sedimentary evidence for distantly-generated tsunamis on the Hawai'ian Islands, opening the way for more comprehensive historical and palaeotsunami studies. Indeed, a brief review of archaeological data suggests that the Hawai'ian coast may have experienced similar large magnitude events in the past, from both local and distant sources. © 2012 Elsevier
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    Reinterpretation of megatsunami inundation in Southeast Australia and the implications for palaeotsunami identification
    (American Geophysical Union, 2011-12-05) Courtney, C; Dominey-Howes, D; Goff, JR; Chagué-Goff, C
    The 2004 Indian Ocean tsunami resulted in a marked increase in concern regarding regions previously considered low risk of tsunami inundation. The southeast coast of Australia has a record suggesting low tsunami risk, with only 47 small tsunamis striking since European arrival. However, the controversial megatsunami hypothesis suggests patterns of massive inundation of the east Australian coast. Given the extreme vulnerability of the NSW coastline due to population concentration and the reliance on boulder deposit evidence, there is a need to provide thorough re-evaluation of the Australian tsunami risk. This re-examination has led to research at four back-beach locations on the south coast of New South Wales, located close to sites reported to contain evidence of megatsunami inundation. Analysis of stratigraphy, sediments, geochemistry and microfossils, plus an extensive radiocarbon chronology of these sites allows for a full reconstruction of the Holocene environments. This success highlights the importance of using multi-proxy diagnostic techniques in investigating potential tsunami inundation sites with relatively short historical records. In the case of NSW, no evidence of Holocene tsunamis has been identified, casting serious doubt on the existing understanding of tsunami risk on the NSW coast and the diagnostic criteria used for identifying tsunami deposits.