The lower Darling Valley contains Cenozoic shallow marine, fluvial, lacustrine and aeolian sediments including a number of previously poorly dated Quaternary fluvial units associated with the Darling River and its anabranches. New geomorphic mapping of the Darling floodplain that utilises a high resolution LiDAR dataset and SPOT imagery, has revealed that the Late Quaternary sequence consists of scroll-plain tracts of different ages incised into a higher more featureless mud-dominated floodplain. Samples for OSL (Optically-Stimulated Luminescence) and radiocarbon dating were taken in tractor-excavated pits, from sonic drill cores and from hand-auger holes from a number of scroll-plain and older floodplain sediments in the Menindee region. The youngest, now inactive, scroll-plain phase, associated with the modern Darling River, was active in the period 5-2 ka. A previous anabranch scroll-plain phase has dates around 20ka. Indistinct scroll-plain tracts older than the anabranch system, are evident both upstream and downstream of Menindee and have ages around 30ka. These three scroll-plain tracts intersect just south of Menindee but are mostly separated upstream and downstream of that point. Older dates of 50 ka, 85 ka and >150 ka have been obtained from lateral-migration sediments present beneath the higher mud-dominated floodplain. Establishing a chronology for the Quaternary fluvial landscape has been important for groundwater investigations in the Darling River floodplain area. More specifically, this has assisted in constraining the 3D mapping of floodplain units, helped constrain conceptual models of surface-groundwater interaction, and aided in the assessment of managed aquifer recharge options.

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.

Six deep seismic reflection profiles totalling ~900 km were acquired across the Mount Isa Province in 2006 (Figure 1). Each vibe point was recorded to ~20 s TWT (two-way travel time), which equates to ~60 km depth. The aims of the survey were to develop a 3D model and a geodynamic history of the province, link deep crustal structure with known mineral deposits, and demonstrate the potential of deep seismic surveys in mineral exploration

Geoscience Australia has developed an interactive 3D viewer for three national datasets; the new Radiometric Map of Australia (Geoscience Australia 2009b), the Magnetic Anomaly Map of Australia (Geoscience Australia 2004), and the Gravity Anomaly Map of the Australian Region (Geoscience Australia 2008). The interactive virtual globe is based on NASA's open source World Wind Java Software Development Kit (SDK) and provides users with easy and rich access to these three national datasets. Users can view eight different representations of the radiometric map and compare these with the magnetic and gravity anomaly maps and satellite imagery; all draped over a digital elevation model. The full dataset for the three map sets is approximately 55GB (in ER Mapper format), while the compressed full resolution images used in the virtual globe total only 1.6GB and only the data for the geographic region being viewed is downloaded to users computers. This paper addresses the processes for selecting the World Wind application over other solutions, how the data was prepared for online delivery, the development of the 3D Viewer using the Java SDK, issues involving connecting to.

The Tsunami Data Access Tool (Tsu-DAT) is intended for use by the emergency management community to understand the offshore tsunami hazard for areas of interest around Australia and to access the large database of tsunami waveforms to generate the required input to a detailed tsunami impact assessment for a given community. The offshore tsunami hazard and resultant waveforms are a result of the probabilistic tsunami hazard assessment (PTHA) of Australia (Burbidge2008a). This assessment modelled thousands of synthetic tsunami to estimate the likelihood of a tsunami wave of a given amplitude occurring at an offshore location, defined at the 100 m depth contour. A database of tsunami waveforms at points along the 100 m depth contour around the Australian coast was created. The Tsu-DAT allows users to search this database and extract tsunami waveforms for events of interest. These waveforms are in a format that can be used to drive more detailed models of tsunami inundation and impact for communities of interest.

The Capel and Faust basins are located in a frontier part of offshore eastern Australia, about 800 km east of Brisbane in 1300-2500 m of water. Little is known of the basin structures and geological history of this area, which is a continental fragment separated from Australia during the Cretaceous rifting of the Tasman Sea. In 2007 Geoscience Australia acquired 6000km of 2D seismic reflection and refraction data, gravity and magnetics, to begin an assessment of the petroleum prospectivity of these basins. A workflow has been developed to assist the seismic interpreter with feedback from a coherent 3D geology model that is used to predict the gravity response of the basins. This response is harmonized with the observed gravity and modified geological horizons are then returned to the seismic interpreter. An interface between Geoframe and Geomodeller has been optimized to make it very easy to do many iterations of this process, as suits the changing needs of the interpretation team.

Extended abstract version of short abstract accepted for conference presentation GEOCAT# 73701

Receiver function studies of Northern Sumatra T. Volti and A. Gorbatov Geoscience Australia, GPO Box 378 Canberra ACT 2601 Australia The Northern Sumatra subduction zone is distinguished by the occurrence of the 2004 Sumatra-Andaman megathrust earthquake and has a peculiar subduction of two major bathymetric structures; the Investigator fracture zone and the Wharton fossil ridge. Four stations in Northern Sumatra (BSI, PSI, PPI, GSI) and two stations in Malaysia (KUM and KOM) have been selected to construct migrated images based on receiver functions (RF) in order to study Earth structure and subduction processes in the region. Waveforms from 304 teleseismic earthquakes with Mb >5.5 and a distance range of 30º to 95º recorded from April 2006 to December 2008 were used for the analysis. The number of RF for each station varies from 20 to 192 depending on the signal/noise ratio. The computed RF clearly show pS conversions at major seismic velocity discontinuities associated with the subduction process where the Moho is visible at 5.5, 4, 3.5, and 2 sec for BSI, PSI, PPI, and GSI, respectively. RF for KUM and KOM have only conversions at the Moho near ~4 sec. The subducted slab is visible below Sumatra as a positive amplitude conversion preceded by a negative one, which we interpret as a low-velocity structure above the subducted slab. RF for PSI located at Toba supervolcano reveal pockets of low-velocity zones extending from a ~50 km depth down to the subducted slab. Forward modellings of RF suggest that seismic velocity contrasts can reach ~18% that is in accordance with previous local tomographic studies.

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 Australian Government formally releases new offshore exploration areas at the annual APPEA conference. In 2012, twenty-eight areas in nine offshore basins are being released for work program bidding. Closing dates for bid submissions are either six or twelve months after the release date, i.e. 8 November 2012 and 9 May 2013, depending on the exploration status in these areas and on data availability.