<div>Two coincident, crustal-scale models, one of magnetic susceptibility and one of density, have been produced for a volume covering the Australian continent and extending down to 55.5 km depth. These models were produced using the UBC‑GIF MAG3D and GRAV3D inversion programs, respectively.</div><div><br></div><div>The inversions were constrained with geological reference models with layers for sediments, undifferentiated crust and the mantle. The reference model for the magnetic inversion incorporated a Curie depth surface below which magnetic susceptibility was set to zero.</div><div><br></div><div>Due to the size of the inversion problem to be solved, the volume was divided into 235 overlapping inversions, which were inverted separately and then recombined. The method of recombining the inversions relies on a cosine function to determine the weight of each property and then takes a weighted average. This method successfully attenuated the edge effects that would otherwise occur between models and allows them to be viewed as one seamless model that covers the whole of Australia.</div><div><br></div><div>Regions of coincident high-density (&gt;2.83 g/cm³) and high-magnetic susceptibility (&gt;0.0125 SI) within the top 8‑9&nbsp;km of the undifferentiated crust are suggested to be related to ultramafic rocks and the magnetite-forming hydrothermal alteration stages of potentially fertile IOCG systems. Currently the models are available in UBCGIF format (.den/.sus) only. Other formats and all supporting input data will be added in the near future. Due to their size, the models have been divided into subsets (labelled 1-17) for download. Please refer to the image below for the extent of the subsets.

The Layered Geology of Australia web map service is a seamless national coverage of Australia’s surface and subsurface geology. Geology concealed under younger cover units are mapped by effectively removing the overlying stratigraphy (Liu et al., 2015). This dataset is a layered product and comprises five chronostratigraphic time slices: Cenozoic, Mesozoic, Paleozoic, Neoproterozoic, and Pre-Neoproterozoic. As an example, the Mesozoic time slice (or layer) shows Mesozoic age geology that would be present if all Cenozoic units were removed. The Pre-Neoproterozoic time slice shows what would be visible if all Neoproterozoic, Paleozoic, Mesozoic, and Cenozoic units were removed. The Cenozoic time slice layer for the national dataset was extracted from Raymond et al., 2012. Surface Geology of Australia, 1:1 000 000 scale, 2012 edition. Geoscience Australia, Canberra.

The Vlaming Sub-Basin CO2 Storage Potential Study web service includes the datasets associated with the study in the Vlaming Sub-basin, located within the southern Perth Basin about 30 km west of Perth. The data in this web service supports the results of the Geoscience Australia Record 2015/009 and appendices. The study provides an evaluation of the CO2 geological storage potential of the Vlaming Sub-basin and was part of the Australian Government's National Low Emission Coal Initiative.

This web service delivers metadata for onshore active and passive seismic surveys conducted across the Australian continent by Geoscience Australia and its collaborative partners. For active seismic this metadata includes survey header data, line location and positional information, and the energy source type and parameters used to acquire the seismic line data. For passive seismic this metadata includes information about station name and location, start and end dates, operators and instruments. The metadata are maintained in Geoscience Australia's onshore active seismic and passive seismic database, which is being added to as new surveys are undertaken. Links to datasets, reports and other publications for the seismic surveys are provided in the metadata.

<div>The Vlaming Sub-Basin CO2 Storage Potential Study data package includes the datasets associated with the study in the Vlaming Sub-basin, located within the southern Perth Basin about 30 km west of Perth. The data in this data package supports the results of the Geoscience Australia Record 2015/009 and appendices. The study provides an evaluation of the CO2 geological storage potential of the Vlaming Sub-basin and was part of the Australian Government's National Low Emission Coal Initiative.</div>

<div>This look-book was developed to accompany the specimen display in the office of the Hon Madeleine King MP, Minister for Resources and Northern Australia. It contains information about each of the specimens including their name, link to resource commodities and where they were from. </div><div><br></div><div>The collection was carefully curated to highlight some of Australia’s well known resources commodities as well as the emerging commodities that will further the Australian economy and contribute to the low energy transition. The collection has been sourced from Geoscience Australia’s National Mineral and Fossil Collection. </div><div><br></div><div>The collection focuses on critical minerals, ore minerals as well as some fuel minerals. These specimens align with some of Geoscience Australia major projects including the Exploring For the Future (EFTF) program, the Trusted Environmental and Geological Information program (TEGI) as well as the Repository and the public education and outreach program.&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</div>

Geoscience Australia’s geomagnetic observatory network covers one-eighth of the Earth. The first Australian geomagnetic observatory was established in Hobart in 1840. This almost continuous 180-year period of magnetic-field monitoring provides an invaluable dataset for scientific research. Geomagnetic storms induce electric currents in the Earth that feed into power lines through substation neutral earthing, causing instabilities and sometimes blackouts in electricity transmission systems. Power outages to business, financial and industrial centres cause major disruption and potentially billions of dollars of economic losses. The intensity of geomagnetically induced currents is closely associated with geological structure. We modelled peak geoelectric field values induced by the 1989 Québec storm for south-eastern Australian states using a scenario analysis. Modelling shows the 3D subsurface geology had a significant impact on the magnitude of induced geoelectric fields, with more than three orders of magnitude difference across conductive basins to resistive cratonic regions in south-eastern Australia. We also estimated geoelectrically induced voltages in the Australian high-voltage power transmission lines by using the scenario analysis results. The geoelectrically induced voltages may exhibit local maxima in the transmission lines at differing times during the course of a magnetic storm depending on the line’s spatial orientation and length with respect to the time-varying inducing field. Real-time forecasting of geomagnetic hazards using Geoscience Australia’s geomagnetic observatory network and magnetotelluric data from the Australian Lithospheric Architecture Magnetotelluric Project (AusLAMP) helps develop national strategies and risk assessment procedures to mitigate space weather hazard. This Abstract was submitted/presented to the 2023 Australian Exploration Geoscience Conference 13-18 Mar (https://2023.aegc.com.au/)

Since the publication of the Global Seismic Hazard Assessment Project (GSHAP) hazard map in 1999, Australia has stood out as a region of high earthquake hazard among its stable continental region (SCR) peers. The hazard map underpinning the GSHAP traces its lineage back to the 1990 assessment of Gaull and others. This map was modified through a process of expert judgement in response to significant Australian earthquakes (notably the MW 6.2, 6.3 and 6.6 1988 Tennant Creek sequence and the deadly 1989 MW 5.4 Newcastle earthquake). The modified map, developed in 1991 (McCue and others, 1993), underpins Standards Australia’s structural design actions to this day (AS1170.4–2007). But does this assessment make sense with our current understanding of earthquake processes in SCRs? Geoscience Australia (GA) have embarked to update the seismic hazard model for Australia through the National Seismic Hazard Assessment (NSHA18) project. Members of the Australian seismological community were solicited to contribute alternative seismic source models for consideration as inputs to the updated Australian NSHA18. This process not only allowed for the consideration of epistemic uncertainty in the hazard model in a more comprehensive and transparent manner, but also provides the community as a whole ownership of the final model. The 3rd party source models were assessed through an expert elicitation process that weighed the opinion of each expert based on their knowledge and ability to judge relevant uncertainties. In total, 19 independent seismic source models (including regional and background area sources, smoothed seismicity and seismotectonic sources) were considered in the complete source model. To ensure a scientifically rigorous, transparent and quality product, GA also established a Scientific Advisory Panel to provide valuable and ongoing feedback during the development of the NSHA18. The NSHA18 update yields many important advances on its predecessors, including: calculation in a full probabilistic framework using the OpenQuake-engine; consistent expression of earthquake magnitudes in terms of MW; inclusion of epistemic uncertainty through the use of third-party source models; inclusion of a national fault-source model based on the Australian Neotectonic Features database; inclusion of epistemic uncertainty on fault occurrence models and earthquake clustering; and the use of modern ground-motion models. The preliminary NSHA18 design values are significantly lower than those in the current (1991-era) AS1170.4–2007 map at the 10% in 50-year probability level. However, draft values at lower probabilities (i.e., 2% in 50-years) are entirely consistent (in terms of the percentage land mass exceeding different PGA thresholds) with other SCRs with low strain rates (e.g. the central & eastern United States). The large reduction in seismic hazard at the 10% in 50-year probability level has led to much consternation amongst the building code committee in terms of whether the new draft design values will allow enough resilience to seismic loads. This process underscores the challenges in developing national-scale PSHAs in slowly deforming regions, where 10% in 50-year probability level may not adequately capture the maximum considered earthquake ground motions. Consequently, a robust discussion is required is amongst the Australian building code committee (including hazard practitioners) to determine alternative hazard and/or risk objectives that could be considered for future standards. Presented at the Probabilistic Seismic Hazard Assessment (PSHA) Workshop 2017, Lenzburg, Switzerland

A shallow MW 5.3 earthquake near Lake Muir in southwest Western Australia on the 16 September 2018 was followed on the 8 November by a co-located MW 5.2 event in the same region. Sentinel-1 synthetic aperture radar interferograms (InSAR) allowed for the timely identification and mapping of the surface deformation relating to both earthquakes. Field mapping, guided by the InSAR observations, revealed that the first event produced an approximately 3 km-long and up to 0.4 m-high west-facing surface rupture. Five seismic rapid deployment kits (RDKs) were installed in the epicentral region within three days of the 16 September event. These data, telemetered to Geoscience Australia’s National Earthquake Alerts Centre, have enabled the detection and location of more than 750 dependent events up to ML 4.6. Preliminary joint hypocentre relocation of aftershocks using data from RDKs confirms an easterly dipping rupture plane for the first MW 5.3 event. The main shocks were recorded throughout the Australian National Seismic Network, in addition to a local broadband network in the Perth Basin operated by University of Texas at Dallas and the University of Western Australia. These data indicate large long-period ground-motions due to Rg phases and basin amplification. The two main shocks were widely felt within the region, including the Perth metro region (300 km away), with over 2400 online felt reports for the 8 November event. The Lake Muir sequence represents the ninth recorded surface rupturing earthquake in Australia in the past 50 years. All of these events have occurred in the Precambrian cratonic terranes of western and central Australia, in unanticipated locations. Paleoseismic studies of these ruptures found no evidence for regular recurrence of large events on the underlying faults. The events might therefore be considered “one-offs” at timescales of significance to typical probabilistic seismic hazard studies. Presented at 2019 Seismological Society of America Conference, Seattle in the special session on “Central and Eastern North America and Intraplate Regions Worldwide”

As the Central Bureau for the Asia Pacific Reference Frame (APREF), Geoscience Australia were keen to transition to the most up-to-date realisation of a trusted global reference frame from the IGS, being IGS20. However, following adoption of ITRF2020/IGS20 there were apparent site-specific, centimetre-level coordinate inconsistencies between ITRF2020/IGS20 and ITRF2014/IGb14, concerningly presenting as an inconsistent height offset across the APREF network. The Asia-Pacific Reference Frame (APREF) is a network consisting of more than 1000 stations across the Asia-Pacific region, including ~700 Australian stations as well as global IGS core stations. For our routine analysis of the network, we process GPS-only double-difference observations in network mode and align them to the global reference frame of choice, using the Bernese software. We process daily solutions, and then stack them to generate weekly solutions. We then take these coordinates and apply the Australian Plate Motion Model to acquire GDA2020 coordinates, which is a plate-fixed national datum used widely across Australia, including to calculate the legally traceable coordinates we provide to station owners and operators. Taking the latest available products (satellite clock and orbit files, and antenna models) from the IGS, APREF (weekly) solutions are aligned to the IGS20 reference system (where IGS20 is the IGS realisation of ITRF2020), however, we found station-specific offsets of our APREF solutions between the ITRF2014/IGb14 and ITRF2020/IG2S0 due to updates in the ground antenna calibration values from igs14.atx to igs20.atx that reached up to 3 cm. Some of the antenna calibration values were updated post-release of ITRF2020 (updates between igsR3.atx and igs20.atx), which results in further inconsistencies at the coordinate level between the APREF solutions and ITRF2020 solutions. This presentation will discuss the challenges faced when implementing a new global frame of reference at the regional level and the impact on downstream users. We commend the IGS for their efforts in providing high quality, openly available products and services and would like to prompt conversation about the consideration of user requirements for the development of downstream products (such as regional reference frames). Abstract to be submitted to/presented at the American Geophysical Union (AGU) Fall Meeting 2023 (AGU23) - https://www.agu.org/fall-meeting