An assumption of probabilistic seismic hazard assessment is that within each source zone the random earthquakes of the past are considered a good predictor of future seismicity. Random earthquakes suggest a Poisson process. If the source zone does not follow a Poisson process then the resulting PSHA might not be valid. The tectonics of a region will effect its spatial distributions. Earthquakes occurring on a single fault, or uniformly distributed, or clustered or random will each have a distinctive spatial distribution. Here we describe a method for both identifying and delineating earthquake clusters and then characterising them. We divide the region into N cells and by counting the number of earthquakes in each cell we obtain a distribution of the number of cells versus the number of earthquakes per cell. This can then be compared to the theoretical Poisson distribution. Areas which deviate from the theoretical Poisson distribution, can then be delineated. This suggests a statistically robust method for determining source zones. Preliminary results suggest that areas of clustering (eg. SWSZ) can also be modelled as a Poisson process which differs from the larger regional Poisson process. The effect of aftershocks and swarms are also investigated.

This map shows the boundary of the security regulated port for the purpose of Maritime Transport & Office Security Act 2003 1 Sheet (Colour) February 2010 Not for sale or public distribution Contact Manager LOSAMBA project, PMD

A growing need to manage marine biodiversity at local, regional and global scales cannot be met by applying the limited existing biological data sets. Abiotic surrogacy is increasingly valuable in filling the gaps in our knowledge of biodiversity hotspots, habitats needed by endangered or commercially valuable species and systems or processes important to the sustained provision of ecosystem services. This review examines the utility of abiotic surrogates across spatial scales with particular regard to how abiotic variables are tied to processes which affect biodiversity and how easily those variables can be measured at scales relevant to resource management decisions.

The global ocean absorbs 30% of anthropogenic CO2 emissions each year, which changes the seawater chemistry. The absorbed CO2 lowers the pH of seawater and thus causes ocean acidification. The pH of the global ocean has decreased by approximately 0.1 pH units since the Industrial Revolution, decreasing the concentration of carbonate ions. This has been shown to reduce the rate of biological carbonate production and to increase the solubility of carbonate minerals. As more CO2 is emitted and absorbed by the oceans, it is expected that there will be continuing reduction in carbonate production coupled with dissolution of carbonate sediments. This study was undertaken as part of a program to collect baseline data from Australia's seabed environments and to assess the likely impacts of ocean acidification on continental shelf sediments. Over 250 samples from four continental shelf areas of northern Australia (Capricorn Reef, Great Barrier Reef Lagoon, Torres Strait, Joseph Bonaparte Gulf) were analysed to characterise the surface sediment mineral and geochemical composition. Of particular importance was the quantification of carbonate minerals (calcite, aragonite, high-magnesium calcite) and the magnesium content in high-magnesium calcite. The latter determines the solubility of high-magnesium calcite, which is most soluble of all common carbonate minerals. The thermodynamic stability of carbonate minerals as referred to the state of saturation was calculated using the current and predicted equatorial ocean water composition [1]. Northern Australian continental shelf sediments are largely dominated by carbonate. High-magnesium calcite had the highest abundance of all carbonate minerals followed by aragonite in all areas. The average mol% MgCO3 in high-magnesium calcite varied from 13.6 to 15.5 mol% for the different areas, which is in agreement with the global average magnesium concentration in high-magnesium calcite in tropical and subtropical regions [2].

Magnetotelluric (MT) data have been acquired in 2008 and 2009 at 40 broadband (0:01 s to 500 s) and 12 long-period (10 s to 10 000 s) sites along the east-west deep seismic reflection transect of northern Eyre Peninsula, South Australia. The MT survey is a joint project between the University of Adelaide and Geoscience Australia and is funded by the Australian Government as part of the Onshore Energy Security Program. Long-period sites are spaced 20 km apart and broadband sites infill this spacing to 10 km with also some 5 km spacing. This ensures sufficient coverage to map the upper crustal to upper mantle structures beneath northern Eyre Peninsula.

As part of initiatives by the Australian and Queensland Governments, four new seismic reflection lines and three corresponding magnetotelluric lines were acquired in 2007 over the Mt Isa, Georgetown and Charters Towers regions. These data, combined with existing multidisciplinary data, have provided new insights into the 3D architecture, geodynamics and economic potential of the North Queensland region.

The Garnaut Climate Change Review commissioned by Australia's State and Territory Governments examined the impacts of, and possible policy responses to, climate change on the Australian economy. This presentation discussed the methodology developed for the Review by Geoscience Australia and the outputs which provided an assessment of the impact of tropical cyclone (TC) hazard on communities in northern Australia. The study utilized predicted changes in the maximum potential intensity (MPI) to define changes in the wind hazard and storm surge potential. The MPI sets a thermodynamic, theoretical upper limit for the distribution of TC intensities for a given vertical temperature and humidity profile and a given location. Associated storm surge impacts were developed using a simple relationship between TC intensity and storm surge height and adopting the IPCC fourth assessment global mid-point sea-level rise predictions. We considered the impact on the residential building stock of severe wind and storm surge hazards associated with a number of IPCC climate change scenarios. Changes in residential building stock, for over 500 coastal statistical local areas (SLA's) from Southeast Queensland anticlockwise to Perth, were forecast using Australian Bureau of Statistics population projections through to 2100. A Probable Maximum Loss (PML) curve for each study region was obtained by considering the return-period hazard over the range from 50 to 5000 years. The average annual cost to the region due to tropical cyclones across this wide time period (5000 years), often referred to as the 'annualised loss', was evaluated for each SLA. Expressing the annualised loss as a percentage of total reconstruction demonstrates the intensity of the risk to a particular community, which is not so evident in simple dollar loss figures.

The Australian National Coastal Vulnerability Assessment (NCVA) was commissioned by the Federal Government to assess the risk to coastal communities from climate related hazards. In addition to an understanding of the impact/risk posed by the current climate, the study also examined the change in risk under a range of future climate scenarios. This assessment will provide information for application to policy decisions for, inter alia, land use, building codes, emergency management and insurance applications. Geoscience Australia coordinated the work undertaken to quantify the impact on property and infrastructure. This included the development of SMARTLINE, a nationally-consistent database of coastal morphology for the entire country, which provides critical information on the geology and landforms and their potential susceptibility to instability or degradation due to environmental or climatic factors. In a first-order attempt to assess the climate-change induced hazard to the coastal landscape, SMARTLINE data have been combined with sea-level rise (SLR) projections for 2030 and 2100, and 1 in 100 year current-climate storm surge estimates to determine potential areas of inundation and zones of instability where coastal recession due to SLR is predicted. Additionally, cyclonic wind hazard along Australia's northern coastline has been estimated using Geoscience Australia's Tropical Cyclone Risk Model, utilising synthetic tropical cyclone event sets derived from IPCC AR4 global climate models. The hazard levels have been modified for terrain, topographic and shielding effects to reflect localised variations in wind hazard.

Abstract attached

Tropical cyclones pose a significant threat to islanders in the tropical western Pacific. The extreme winds from these severe storms can cause extensive damage to housing, infrastructure and food production, whilst low lying areas can be adversely affected by storm surge inundation. As part of the Pacific Climate Change Science Program (PCCSP), Geoscience Australia is assessing the wind hazard posed by tropical cyclones for 14 islands in the western Pacific and Timor Leste. The assessment will cover both the current climate as well as projections for future climate scenarios. Wind hazard maps are being generated using Geoscience Australia's open-source Tropical Cyclone Risk Model (TCRM) that applies a statistical-parametric process to estimate return period wind speeds. The climate projections are produced by applying this model to downscaled storm tracks from global climate models. Two types of downscaled tracks are used for the projections: tracks of tropical-cyclone-like vortices directly detected in dynamically downscaled climate simulations and tracks derived from GCM's using a statistical/deterministic model (Emanuel 2006). The presentation will provide an outline of the method applied.