Seismic line 07GA-IG2, described here, forms part of the Isa-Georgetown-Charters Towers seismic survey that was acquired in 2007. The seismic line is oriented approximately east-west and extends from east of Croydon in the west to near Mt Surprise in the east (Figure 1). The acquisition costs for this line were provided jointly by the Geological Survey of Queensland and Geoscience Australia, and field logistics and processing were carried out by the Seismic Acquisition and Processing team from Geoscience Australia. Three discrete geological provinces have been interpreted on this seismic section (Figure 2). Two of these, the Numil and Abingdon Provinces, only occur in the subsurface. The upper crustal part of the seismic section consists of the Paleo- to Mesoproterozoic Etheridge Province, which here includes the Croydon Volcanic Group in the western part of the Province. In this east-west profile, the crust is essentially two-layered, with a strongly reflective lower crust defining the Numil and Abingdon Provinces and a less reflective upper crust being representative of the Etheridge Province.

Mount Merapi in Indonesia has experienced a number of VEI 3 (Volcano Explosivity Index) eruptions in historical times. This animation simulates a 'what if' scenario for a VEI 5 eruption of Mount Merapi using the output results from a volcanic ash hazard model called FALL3D-5.1.1. The simulated eruption occurs over a 12 hour period with a modelled eruption column height of 30 km. The prevailing wind direction is modelled to the southwest towards the nearby city of Yogyakarta (28 km). The animation shows the increase in volcanic ash thickness on the ground over time. The simulation shows that if Mount Merapi erupted under these conditions the city of Yogyakarta could experience ash thicknesses on the ground between 1 and 15 m including thicknesses of 7 - 8 m at the nearby Adisucipto International Airport.

ABSTRACT Oil and gas reservoirs below the sea bed can experience seepage through the seafloor, resulting in oil slicks on the sea surface. Remote sensing has the potential to cost-effectively scan extensive and/or remote regions for such surface slicks, thereby identifying areas in producing and frontier basins that are prospective for hydrocarbons. Accordingly, we are developing a two-pronged, remote sensing-based approach for seepage slick studies in the Australian Marine Jurisdiction (AMJ): 1) Detection : building a semi-automated processing and classification system in order to scan large numbers of SAR scenes for potential natural slick targets. This includes time series analysis. 2) Identification : investigating the potential of optical remote sensing as a diagnostic tool for further, targeted study. Here, we present the.....

The Southwest Margin of Australia includes the Paleozoic to Mesozoic Perth basin. Depth-to-basement and basement structure and composition across this region remain poorly understood due to a limited extent of exposed basement outcrop, few wells intersect basement and the lack of resolvable basement horizon in many of the seismic lines. This study uses the integrated modelling and interpretation of all available geophysical and geological datasets to produce new interpretive maps of basement architecture, composition and structural fabric to better characterise the nature of basement across the region. The basement domain, structure and composition maps have been constructed through the integrated interpretation of all available geological and geophysical datasets, including outcrop, wells, geochronology, seismic, gravity, magnetic and bathymetry datasets. These products are predictive tools for better understanding structural reactivation patterns and associated changes in basin geometry through time, as well as variations in basement derived heat flow. A depth-to-basement model was developed using the Spector and Grant method, implemented using custom software. Depths are measured from straight line segments in the azimuthally averaged power density spectrum of sub-sectioned magnetic grids. This allows additional geological and geophysical data (e.g. wells, surface outcrop, gravity and seismic interpretations) to be integrated into the workflow, resulting in a more geologically plausible model. The model provides a new view of Perth basin geometry, not obtainable from seismic data alone, which highlights the location and geometry of key depocentres and provides additional constraints on the possible thickness of pre- and early syn-rift sediments.

Abstract for SGA Townsville 2009

Predictive maps of the subsurface can be generated when geophysical datasets are modelled in 2D and 3D using available geological knowledge. Inversion is a process that identifies candidate models which explain an observed dataset. Gravity, magnetic, and electromagnetic datasets can now be inverted routinely to derive plausible density, magnetic susceptibility, or conductivity models of the subsurface. The biggest challenge for such modelling is that any geophysical dataset may result from an infinite number of mathematically-plausible models, however, only a very small number of those models are also geologically plausible. It is critical to include all available geological knowledge in the inversion process to ensure only geologically plausible physical property models are recovered. Once a set of reasonable physical property models are obtained, knowledge of the physical properties of the expected rocks and minerals can be used to classify the recovered physical models into predictive lithological and mineralogical models. These predicted 2D and 3D maps can be generated at any scale, for Government-funded precompetitive mapping or drilling targets delineation for explorers.

Three seismic lines (10GA-CP1, 10GA-CP2 and 10GA-CP3), which cross north to south across the Capricorn Orogen of Western Australia, have recently been collected by Geoscience Australia, ANSIR and the Geological Survey of Western Australia. The interpretation of these seismic lines is aimed at providing insight into the geologic structure of the Capricorn Orogen and to explore the relationship between the Pilbara and Yilgarn cratons. To aid in further interpretation and to add value to the seismic data an analysis of the available potential field data (gravity and magnetics) has also been undertaken. A range of geophysical data analysis techniques have been applied and include: multi-scale edge detection (worms), forward modelling and 3D inversion. By applying all three analysis techniques to the potential-field data major trends, contrasting properties and regional blocks relating to the subsurface geology have been determined, in turn, allowing for a detailed comparison with the seismic interpretation. Note that all results referred to in this abstract are preliminary and subject to change.

Broken Hill Managed Aquifer recharge Projects 3D models and Fly-through

Abstract. Severe wind is one of the major natural hazards in Australia. The component contributors to economic loss in Australia with regards to severe wind are tropical cyclones, thunderstorms and sub-tropical (synoptic) storms. Geoscience Australia's Risk and Impact Analysis Group (RIAG) is developing mathematical models to study a number of natural hazards including wind hazard. This paper discusses wind hazard under current and future climate using RIAG's synoptic wind hazard model. This model can be used in non-cyclonic regions of Australia (Region A in the Australian-New Zealand Wind Loading Standard; AS/NZS 1170.2:2002) where the wind hazard is dominated by synoptic and thunderstorm gust winds.

The first RSTT model for Australia has been developed based on the Australian Seismological Reference Model (AuSREM) that was released in late 2012. The densely-gridded P and S wave distributions of the crust and upper mantle of AuSREM have been simplified and translated into the 7 layer crustal and upper mantle RSTT model. Travel times computed with this RSTT model are evaluated against travel times computed in full 3D through the AuSREM model to assess the impact of the approximations used by RSTT. Location estimates of 5 ground truth earthquakes (GT1, GT2 and GT5) using the global ak135 reference model, the RSTT model and the full 3D travel times are compared. It is found that the RSTT model can reproduce the 3D travel times fairly accurately within its distance of applicability, thereby improving location estimates compared to using a global travel time model like ak135. However the benefit of using RSTT for locating Australian earthquakes is far less than using full 3D travel times, mainly because most stations tend to be further away from the source than the distance of RSTT applicability.