Reinterpretation of megatsunami inundation in Southeast Australia and the implications for palaeotsunami identification

Courtney, C; Dominey-Howes, D; Goff, JR; Chagué-Goff, C

Reinterpretation of megatsunami inundation in Southeast Australia and the implications for palaeotsunami identification

Date

2011-12-05

Authors

Publisher

American Geophysical Union

Abstract

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.

Keywords

Indian Ocean, Tsunamis, Australia, Coastal regions, Hazards, Natural disasters, New South Wales, Hypothesis, Geologic deposits, Sediments, Carbon 14

Citation

Courtney, C., Dominey-Howes, D., Goff, J. R., & Chagué-Goff, C. (2011). Reinterpretation of megatsunami inundation in Southeast Australia and the implications for palaeotsunami identification. Paper presented at the American Geophysical Union Fall Meeting 2011, San Francisco, California, 5 December 2011 to 9 December 2011.