The GA record contains abstracts of the contributions given at the "Geologically realistic inversion of gravity and magnetic data" workshop, held in Melbourne on 1 July 2006 as a prelude to the Australian Earth Sciences Convention 2006 (AESC 2006). The accompanying CD-ROM contains the abstracts given at the workshop in PDF format.

This report is part of the results of a study into the potential for the geological storage of carbon dioxide within the Triassic Formations of the Galilee Basin in central Queensland carried out in Geoscience Australia on behalf of the CO2CRC. A review of the geological potential of the area has been issued as a separate report (Marsh et al., 2008) and this document describes the construction of a static geological model of one of the potential reservoirs in one area of the basin, while the results of a preliminary dynamic simulation study based on this model will be presented in a separate report by the reservoir engineer Yildiray Cinar of UNSW.

In August 2002 the Council of Australian Governments (COAG) published a review of natural disaster relief and mitigation arrangements in Australia (COAG, 2003). One of the recommendations from this review included a commitment by COAG to develop and implement a five-year national program of systematic and rigorous disaster risk assessments. In response to this commitment, Geoscience Australia has undertaken a series of national risk assessments for a range of natural hazards including severe wind. This study includes four case studies representing different wind regions Perth (Region A), Brisbane (Region B), Gold Coast (Region B) and Cairns (Region C) to estimate the wind risk. Severe wind is one of the major natural hazards in Australia. These severe winds are chiefly produced by cyclones in the north and cold fronts or thunderstorms in the south. Geoscience Australia has developed a national wind hazard model for estimating the risk posed by peak wind gusts. In this study, the regional return period wind gusts used were as defined in the Australian/New Zealand wind loading standard (AS/NZS 1170.2, 2002) and applied the methodology detailed in the standard. The impact of severe wind varies considerably between structures at various locations, due to the geographic terrain, the height of the structure concerned, the surrounding structures and topographic factors. The wind multipliers defined in the AS/NZS 1170.2 can numerically describe the site wind exposure and speed modifications. These multipliers give quantitative measures of local wind conditions relative to the regional wind speed (defined as open terrain at 10 metre height) at each location. There are three local wind multipliers named terrain/height multiplier (Mz), shielding multiplier (Ms) and topographic (also called hill-shape) multiplier (Mh) influence the regional wind speed. The developed model estimates these multipliers using remote sensing and spatial information. The directional multiplier (Md) is considered from the standards determines the wind direction The relationship between the regional wind speed (VR) in open terrain at 10 metre height, the maximum local (site) wind speed (Vsite) and the local wind multipliers is: Vsite = VR × Md ×Mz × Ms × Mh The wind loading standard is known to be conservative in its approach to shielding by buildings upwind in a "shielding zone", and also with regard to the topographic shielding of structures. A number of modifications were made to remove the conservatism associated with AS/NZS 1170.2. The link between incident wind speed and loss is the structural vulnerability and contents loss model. For this study the models developed by George Walker for North Queensland structures using insurance loss data form two cyclone events have been used after validation. Damage levels across each region were assessed for various return periods (50-, 100-, 200-, 500-, 1000-, 2000- year). Severe wind damage losses were determined for each return period hazard level. Each city data set was regressed to obtain a corresponding Probable Maximum Loss (PML) curve. Finally the regression curves were used to determine annualised losses for each study area. The annualised percentage losses were estimated for Perth (0.0039), Brisbane (0.021), Gold Coast (0.04) and Cairns (0.137). In addition, spatially variable regional wind speeds for Perth region were estimated using eight weather stations data and linear interpolation techniques. The wind damage estimated using these wind speeds is significantly higher than the estimated from single station based wind speeds of AS/NZS 1170.2.

The Tanami 3D model is a crustal scale model that integrates geological mapping with seismic interpretation and gravity modelling in order to enhance our understanding of the 3D architecture of the region. The Tanami region is a multiply deformed Palaeoproterozoic terrain consisting of the predominantly turbiditic Tanami Group, the volcanically derived sedimentary and extrusive rocks of the Ware Group and the Mount Charles Formation. The region is thought to be underlain by Archaean age basement, was intruded by numerous granitoid bodies during the period 1820-1790 Ma and hosts the Callie world-class and several smaller gold deposits. The 2005 Tanami seismic survey consisted of four regional traverses. Interpreted sections show the presence of a series of crustal-penetrating structures, that appear to be fundamental to the evolution of the Tanami region. A number of these interpreted structures appear to link the mid-crust to `thin-skinned" structures within the uppermost crust. The seismic also shows the presence of a southeast-dipping suture and associated pop-up structure, that separates the Tanami crust from the Arunta crust. Known ore deposits are all located in close proximity to these interpreted through-going thrust faults and the associated ramp anticlines. Gravity modelling of the southeast-trending backbone seismic traverse supports the seismic interpretation. The current 3D model was constructed using 3D GeoModeller; with the seismic data, modelled gravity, interpreted magnetic and gravity data and geological mapping. The 3D model forms the basis of the Tanami X3D, web viewing tool, which allows the model and associated data to be viewed and manipulated over the web.

Animation of earthquake generated tsunami created in 3D Studio Max for the Risk Research Group.

Tsunami inundation models are computationally intensive and require high resolution elevation data in the nearshore and coastal environment. In general this limits their practical application to scenario assessments at discrete communities. This paper explores the use of moderate resolution (250 m) bathymetry data to support computationally cheaper modelling to assess nearshore tsunami hazard. Comparison with high resolution models using best available elevation data demonstrates that moderate resolution models are valid at depths greater than 10 m in areas of relatively low sloping, uniform shelf environments, however in steeper and more complex shelf environments they are only valid to depths of 20 m or greater. In contrast, arrival times show much less sensitivity to resolution. It is demonstrated that modelling using 250 m resolution data can be useful in assisting emergency managers and planners to prioritise communities for more detailed inundation modelling by reducing uncertainty surrounding the effects of shelf morphology on tsunami propagation. However, it is not valid for modelling tsunami inundation.

A nationally-consistent wave resource assessment is presented for Australian shelf (<300 m) waters. Wave energy and power were derived from significant wave height and period, and wave direction hindcast using the AusWAM model for the period 1 March 1997 to 29 February 2008 inclusive. The spatial distribution of wave energy and power is available on a 0.1° grid covering 110'156° longitude and 7'46° latitude. Total instantaneous wave energy on the entire Australian shelf is on average 3.47 PJ. Wave power is greatest on the 3,000 km-long southern Australian shelf (Tasmania/Victoria, southern Western Australia and South Australia), where it widely attains a time-average value of 25-35 kW m-1 (90th percentile of 60-78 kW m-1), delivering 800-1100 GJ m-1 of energy in an average year. New South Wales and southern Queensland shelves, with moderate levels of wave power (time-average: 10-20 kW m-1; 90th percentile: 20-30 kW m-1), are also potential sites for electricity generation due to them having a similar reliability in resource delivery to the southern margin. Time-average wave power for most of the northern Australian shelf is <10 kW m-1. Seasonal variations in wave power are consistent with regional weather patterns, which are characterised by winter SE trade winds/summer monsoon in the north and winter temperate storms/summer sea breezes in the south. The nationally-consistent wave resource assessment for Australian shelf waters can be used to inform policy development and site-selection decisions by industry.

This paper describes two studies modelling the potential impacts of extreme events under sea level rise scenarios in two potentially vulnerable coastal communities: Mandurah and Busselton in Western Australia. These studies aim to support local adaptation planning by high resolution modelling of the impacts from climate change.

Data is currently being used, and reused, in ecological research at unprecedented rates. To ensure appropriate reuse however, we need to ask the question: “Are aggregated databases currently providing the right information to enable effective and unbiased reuse?” We investigate this question, with a focus on designs that purposefully bias the selection of sampling locations (upweighting the probability of selection of some locations). These designs are common and examples are those that have unequal inclusion probabilities or are stratified. We perform a simulation experiment by creating datasets with progressively more bias, and examine the resulting statistical estimates. The effect of ignoring the survey design can be profound, with biases of up to 250% when naive analytical methods are used. The bias is not reduced by adding more data. Fortunately, the bias can be mitigated by using an appropriate estimator or an appropriate model. These are only applicable however, when essential information about the survey design is available: the randomisation structure (e.g. inclusion probabilities or stratification), and/or covariates used in the randomisation process. The results suggest that such information must be stored and served with the data to support inference and reuse. <b>Citation: </b>S.D. Foster, J. Vanhatalo, V.M. Trenkel, T. Schulz, E. Lawrence, R. Przeslawski, and G.R. Hosack. 2021. Effects of ignoring survey design information for data reuse. Ecological Applications 31(6): e02360. 10.1002/eap.2360

Basin evolution of the Vlaming Sub-basin and the deep-water Mentelle Basin, both located offshore on the southwest Australian continental margin, were investigated using 2D and 3D petroleum system modelling. Compositional kinetics, determined on the main source sequences, were used to predict timing of hydrocarbon generation and migration as well as GOR evolution and phase behaviour in our 2D and 3D basin models. The main phase of petroleum generation in the Vlaming Sub-basin occurred at 150 Ma and ceased during following inversion and erosion episodes. Only areas which observed later burial have generated additional hydrocarbons during the Tertiary and up to present day. The modelling results indicate the likely generation and trapping of light oils for the Jurassic intervals for a variety of structural traps. It is these areas which are of greatest interest from an exploration point of view. The 2D numerical simulations in the Mentelle Basin indicate the presence of active hydrocarbon generating kitchen areas. Burial histories and generalized petroleum evolutionary histories are investigated.