Earth system sciences
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<div>The wet tropospheric component and clock phase variations are the most important factors that limit the accuracy of the geodetic VLBI products. These fast fluctuations can be introduced into the parametric model as a correlated stochastic noise and treated in a special way using the least square collocation method (LSCM). An a-priori covariance function is used to construct the non-diagonal covariance matrix. We have developed a procedure to calculate the wet troposphere delay and the clock offset for each observation epoch. The wet troposphere delays calculated by the LSCM are in perfect agreement with the water vapour radiometer (WVR) data, within the uncertainty of 2-3 mm. This information is then incorporated into the NGS data file and used in the second iteration. As a result, the procedure for analysing the VLBI data becomes simpler and faster, since the remaining observational error is Gaussian, and the matrix of the observational covariance can be treated as diagonal. For the calibrated VLBI data, the simple least squares method (without breaking the 24-hour experiment into small bins) is applied, followed by a reduction in the number of estimated parameters. All VLBI data between 1993 and 2023 were processed with pre-calibrated tropospheric and clock delays. The result was tested with two independent software packages, OCCAM and VieVS, and showed a good efficiency with respect to the traditional approach. The accuracy of the estimates reaches: 1 mm for VLBI site positions, 3 µas for UT1-UTC values, 40 mas for X- and Y-pole components. The formal error of the most observed ICRF reference radio source positions drops to 1-2 µas, and the ”floor” (or ”inflated”) error for the future ICRF realization would also be reduced. This paper shows that the new data analysis procedure produces results which align with the announced VGOS goals for the S/X VLBI data. Finally we report a detection of the negative parallax effect with an amplitude of −15.8(±0.5) µas. Abstract presented at the 2024 13th General Meeting of the International VLBI Service for Geodesy and Astrometry (IVS), Tsukuba, Japan
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<div>This data package contains interpretations of airborne electromagnetic (AEM) conductivity sections in the Exploring for the Future (EFTF) program’s Eastern Resources Corridor (ERC) study area, in south eastern Australia. Conductivity sections from 3 AEM surveys were interpreted to provide a continuous interpretation across the study area – the EFTF AusAEM ERC (Ley-Cooper, 2021), the Frome Embayment TEMPEST (Costelloe et al., 2012) and the MinEx CRC Mundi (Brodie, 2021) AEM surveys. Selected lines from the Frome Embayment TEMPEST and MinEx CRC Mundi surveys were chosen for interpretation to align with the 20 km line-spaced EFTF AusAEM ERC survey (Figure 1).</div><div>The aim of this study was to interpret the AEM conductivity sections to develop a regional understanding of the near-surface stratigraphy and structural architecture. To ensure that the interpretations took into account the local geological features, the AEM conductivity sections were integrated and interpreted with other geological and geophysical datasets, such as boreholes, potential fields, surface and basement geology maps, and seismic interpretations. This approach provides a near-surface fundamental regional geological framework to support more detailed investigations. </div><div>This study interpreted between the ground surface and 500 m depth along almost 30,000 line kilometres of nominally 20 km line-spaced AEM conductivity sections, across an area of approximately 550,000 km2. These interpretations delineate the geo-electrical features that correspond to major chronostratigraphic boundaries, and capture detailed stratigraphic information associated with these boundaries. These interpretations produced approximately 170,000 depth estimate points or approximately 9,100 3D line segments, each attributed with high-quality geometric, stratigraphic, and ancillary data. The depth estimate points are formatted for compliance with Geoscience Australia’s (GA) Estimates of Geological and Geophysical Surfaces (EGGS) database, the national repository for standardised depth estimate points. </div><div>Results from these interpretations provided support to stratigraphic drillhole targeting, as part of the Delamerian Margins NSW National Drilling Initiative campaign, a collaboration between GA’s EFTF program, the MinEx CRC National Drilling Initiative and the Geological Survey of New South Wales. The interpretations have applications in a wide range of disciplines, such as mineral, energy and groundwater resource exploration, environmental management, subsurface mapping, tectonic evolution studies, and cover thickness, prospectivity, and economic modelling. It is anticipated that these interpretations will benefit government, industry and academia with interest in the geology of the ERC region.</div>
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<div>The Petroleum Systems Summary database stores the compilation of the current understanding of petroleum systems information by basin across Australia. The Petroleum Systems Summary database and delivery tool provide high-level information of the current understanding of key petroleum systems for areas of interest. For example, geological studies in the Exploring for the Future (EFTF) program have included the Canning, McArthur and South Nicholson basins (Carr et al., 2016; Hashimoto et al., 2018). The database and tool aim to assist geological studies by summarising and interpreting key datasets related to conventional and unconventional hydrocarbon exploration. Each petroleum systems summary includes a synopsis of the basin and key figures detailing the basin outline, major structural components, data availability, petroleum systems events chart and stratigraphy, and a précis of the key elements of source, reservoir and seal. Standardisation of petroleum systems nomenclature establishes a framework for each basin after Bradshaw (1993) and Bradshaw et al. (1994), with the source-reservoir naming conventions adopted from Magoon and Dow (1994). </div><div><br></div><div>The resource is accessible via the Geoscience Australia Portal (https://portal.ga.gov.au/) via the Petroleum Systems Summary Tool (Edwards et al., 2020).</div>
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<div>The annual Asia Pacific Regional Geodetic Project (APRGP) GPS campaign is an activity of the Geodetic Reference Frame Working Group (WG) of the Regional Committee of United Nations Global Geospatial Information Management for Asia and the Pacific (UN-GGIM-AP). This document describes the data analysis of the APRGP GPS campaign undertaken between the 10th and 17nd of September 2023. Campaign GPS data collected at 124 sites in nine countries across the Asia Pacific region were processed using version 5.2 of the Bernese GNSS Software in a regional network together with selected IGS (International GNSS Service) sites. The GPS solution was constrained to the ITRF2020 reference frame by adopting IGS20 coordinates on selected IGS core reference sites and using the final IGS earth orientation parameters and satellite ephemerides products. The average of the root mean square repeatability of the station coordinates for the campaign was 2.5 mm, 2.5 mm and 6.9 mm in north, east and up components of station position respectively.</div><div><br></div>
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<div>On January 15, 2022, an ongoing eruption at the Hunga volcano generated a large explosion which resulted in a globally observed tsunami and atmospheric pressure wave. This paper presents time series observations of the event from Australia including 503 mean sea level pressure (MSLP) sensors and 111 tide gauges. Data is provided in its original format, which varies between data providers, and a post-processed format with consistent file structure and time-zone. High-pass filtered variants of the data are also provided to facilitate study of the pressure wave and tsunami. For a minority of tide gauges the raw sea level data cannot be provided, due to licence restrictions, but high-pass filtered data is always provided. The data provides an important historical record of the Hunga volcano pressure wave and tsunami in Australia. It will be useful for research in atmospheric and ocean waves associated with large volcanic eruptions. <b>Citation:</b> Davies, G., Wilson, K., Hague, B. et al. Australian atmospheric pressure and sea level data during the 2022 Hunga-Tonga Hunga-Ha’apai volcano tsunami. <i>Sci Data</i> <b>11</b>, 114 (2024). https://doi.org/10.1038/s41597-024-02949-2
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<div>A document outlining how geoscientific data can be useful for farmers and engagement tool for geoscientists interacting with farmers and pastoralists.</div>
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<div>This record links to tarred folders with simulation files used for a study on tsunami hazards in Tongatapu (eCat 146012) - DOI: https://doi.org/10.1093/gji/ggac140. </div><div><br></div><div>Access to this data will only be available by request via datacatalogue@ga.gov.au</div><div><br></div><div>The files were created using code here: </div><div>https://github.com/GeoscienceAustralia/ptha/tree/master/misc/monte_carlo_paper_2021. </div><div><br></div><div>This code should be read to understand the structure and contents of the tar archives. The simulation files are large and for most use cases you won't need them. First check if your needs a met via code and documentation at the link above. If the git repository doesn't include links to what you need, then it may be available in these tar archives. Contents include the datasets used to setup the model and the model outputs for every scenario. While the modelling files and code were developed by GA, at the time of writing, we do not have permission to distribute some of the input datasets outside of GA (including the Tongatapu LIDAR). </div><div><br></div><div>Access to this data will only be available by request via datacatalogue@ga.gov.au</div>
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<div>Mineral prospectivity studies seek to map evidence of mineral system activity, with the aim of informing mineral exploration decisions and guiding exploration in the face of uncertainty. These studies leverage the growing volumes of information that are available to characterise the lithosphere by compiling covariate (or feature) grids that represent key mineral system ingredients. Previous studies have been categorised as either “knowledge-driven” or “data-driven” approaches depending on whether these grids are integrated via expert elicitation or by the empirical relationship to known mineralisation, respectively. However, to our knowledge, the underlying modelling framework and assumptions have not been systematically reviewed to understand how choices in the approach to the problem influence modelling outcomes. Here we show the broad mathematical equivalence in these approaches and highlight the limitations inherent when optimising to minimise misfit in potentially under-determined problems. We argue that advances in mineral prospectivity are more likely to be driven by careful consideration of the model selection problem. Focusing effort on model selection will not only drive more robust mineral prospectivity predictions but may also simultaneously refine our understanding of key mineral system processes. To build on these results, we present the Mineral Potential Toolkit; a software repository to facilitate feature engineering, statistical appraisal, and quantitative prospectivity modelling. The toolkit enables a novel approach that combines the best aspects of previous methods. Abstract presented to the 26th World Mining Congress 2023 (https://wmc2023.org/)
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<div>The annual Asia Pacific Regional Geodetic Project (APRGP) GPS campaign is an activity of the Geodetic Reference Frame Working Group (WG) of the Regional Committee of United Nations Global Geospatial Information Management for Asia and the Pacific (UN-GGIM-AP). This document describes the data analysis of the APRGP GPS campaign undertaken between the 11th and 17nd of September 2022. Campaign GPS data collected at 116 sites in seven countries across the Asia Pacific region were processed using version 5.2 of the Bernese GNSS Software in a regional network together with selected IGS (International GNSS Service) sites. The GPS solution was constrained to the ITRF2014 reference frame by adopting IGS14 coordinates on selected IGS reference sites and using the final IGS earth orientation parameters and satellite ephemerides products. The average of the root mean square repeatability of the station coordinates for the campaign was 2.0 mm, 2.4 mm and 7.5 mm in north, east and up components of station position respectively.</div>
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<div>Offshore probabilistic tsunami hazard assessments (PTHAs) are increasingly available for earthquake generated tsunamis. They provide standardized representations of tsunami scenarios, their uncertain occurrence-rates, and models of the deep ocean waveforms. To quantify onshore hazards it is natural to combine this information with a site-specific inundation model, but this is computationally challenging to do accurately, especially if accounting for uncertainties in the offshore PTHA. This study reviews an efficient Monte Carlo method recently proposed to solve this problem. The efficiency comes from preferential sampling of scenarios that are likely important near the site of interest, using a user-defined importance measure derived from the offshore PTHA. The theory of importance sampling enables this to be done without biasing the final results. Techniques are presented to help design and test Monte Carlo schemes for a site of interest (before inundation modelling) and to quantify errors in the final results (after inundation modelling). The methods are illustrated with examples from studies in Tongatapu and Western Australia.</div> Abstract submitted/presented to the International Conference on Coastal Engineering (ICCE) 2022 - Sydney (https://icce2022.com/). Citation: Davies, G. (2023). FROM OFFSHORE TO ONSHORE PROBABILISTIC TSUNAMI HAZARD ASSESSMENT WITH QUANTIFIED UNCERTAINTY: EFFICIENT MONTE CARLO TECHNIQUES. <i>Coastal Engineering Proceedings</i>, (37), papers.18. https://doi.org/10.9753/icce.v37.papers.18