2011 Postgraduate Research Competition - UNSW Science - The ...

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Reinterpretation of Megatsunami Inundation in
Southeast Australia and the Implications for
Palaeotsunami Identification
Abstract
Claire Courtney, Dale Dominey-Howes, James Goff and Catherine Chague-Goff
School of Biological, Earth & Environmental Sciences
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.
Abstract
Do animals on the ground really need trees
Alan Kwok and David Eldridge
School of Biological, Earth & Environmental Sciences
Mallee woodlands are an important ecological community in semi-arid eastern Australia,
whose distribution has been substantially reduced since European settlement. Within mallee
communities, substantial leaf litter accumulates around the trees, while the areas between
the trees are virtually litter–free. Consequently the community is dominated by two major
patch types; deep dense litter and bare soil. My research focuses on arthropod (insects,
spiders, slaters) use of these two patches, and indicates that leaf litter is a crucial component
of these mallee ecosystems, structuring fine- and broad-scale biodiversity. In areas not burnt
by fire for several decades, leaf litter is abundant under the tree canopy and supports a
different composition of arthropods such as slaters and jumping spiders, compared to areas
devoid of leaf litter. In contrast, in recently burnt communities, the area under the tree
canopy has considerably less leaf litter and therefore there are fewer differences between
canopy and open areas. Furthermore, slaters are virtually absent in recently burnt
communities. My research illustrates that patterns of arthropod biodiversity in mallee
woodlands are dependent upon environmental characteristics that vary over tens of metres
(leaf litter), and that this is intrinsically tied to broad-scale ecological processes such as fire.
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