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.

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.

All modern ground motion prediction equations (GMPEs) are now calibrated to the moment magnitude scale MW, it is therefore essential that earthquake rates are also expressed in terms of moment magnitudes for probabilistic seismic hazard analyses. However, MW is not routinely estimated for earthquakes in Australia because of Australia’s low-to-moderate level of seismicity, coupled with the relatively sparse seismic recording networks. As a result, the Australian seismic catalogue has magnitude measures mainly based on local magnitudes, ML. To homogenise the earthquake catalogue based on a uniform MW, a “reference catalogue” that includes earthquakes with available MW estimates was compiled. This catalogue consists of 240 earthquakes with original MW values between 2.0 and 6.58. The reference catalogue served as the basis for the development of magnitude conversion equations between MW and ML. The conversions are developed using general orthogonal regression. Different functional forms for the conversion equations were considered and their impact on seismic hazard is explored. Synthetic earthquake catalogues with a “known” ­b-value are generated about an arbitrary location. These catalogues are subsequently perturbed according to different magnitude adjustment assumptions. It is found that the results of seismic hazard analyses at our site are sensitive to the implementation algorithm of such equations. For the considered scenario, the results show a 20-40% reduction in PGA hazard (at the 10% in 50-year probability of exceedance level), depending on the selection of the functional form as well as the method for applying the magnitude conversion equations. Presented at the 2018 Seismological Society of America (SSA) Annual Meeting

This map is part of the AUSTopo - Australian Digital Topographic Map Series. It covers the whole of Australia at a scale of 1:250 000 (1cm on a map represents 2.5 km on the ground) and comprises 516 maps. This is the largest scale at which published topographic maps cover the entire continent. Each standard map covers an area of approximately 1.5 degrees longitude by 1 degree latitude or about 150 kilometres from east to west and at least 110 kilometres from north to south. The topographic map shows approximate coverage of the sheets. The map may contain information from surrounding map sheets to maximise utilisation of available space on the map sheet. There are about 50 special maps in the series and these maps cover a non-standard area. Typically, where a map produced on standard sheet lines is largely ocean it is combined with its landward neighbour. These maps contain natural and constructed features including road and rail infrastructure, vegetation, hydrography, contours (interval 50m), localities and some administrative boundaries. Coordinates: Geographical and MGA Datum: GDA94, GDA2020, AHD. Projection: Universal Traverse Mercator (UTM) Medium: Digital PDF download.

This map is part of the AUSTopo - Australian Digital Topographic Map Series. It covers the whole of Australia at a scale of 1:250 000 (1cm on a map represents 2.5 km on the ground) and comprises 516 maps. This is the largest scale at which published topographic maps cover the entire continent. Each standard map covers an area of approximately 1.5 degrees longitude by 1 degree latitude or about 150 kilometres from east to west and at least 110 kilometres from north to south. The topographic map shows approximate coverage of the sheets. The map may contain information from surrounding map sheets to maximise utilisation of available space on the map sheet. There are about 50 special maps in the series and these maps cover a non-standard area. Typically, where a map produced on standard sheet lines is largely ocean it is combined with its landward neighbour. These maps contain natural and constructed features including road and rail infrastructure, vegetation, hydrography, contours (interval 50m), localities and some administrative boundaries. Coordinates: Geographical and MGA Datum: GDA94, GDA2020, AHD. Projection: Universal Traverse Mercator (UTM) Medium: Digital PDF download.

This map is part of the AUSTopo - Australian Digital Topographic Map Series. It covers the whole of Australia at a scale of 1:250 000 (1cm on a map represents 2.5 km on the ground) and comprises 516 maps. This is the largest scale at which published topographic maps cover the entire continent. Each standard map covers an area of approximately 1.5 degrees longitude by 1 degree latitude or about 150 kilometres from east to west and at least 110 kilometres from north to south. The topographic map shows approximate coverage of the sheets. The map may contain information from surrounding map sheets to maximise utilisation of available space on the map sheet. There are about 50 special maps in the series and these maps cover a non-standard area. Typically, where a map produced on standard sheet lines is largely ocean it is combined with its landward neighbour. These maps contain natural and constructed features including road and rail infrastructure, vegetation, hydrography, contours (interval 50m), localities and some administrative boundaries. Coordinates: Geographical and MGA Datum: GDA94, GDA2020, AHD. Projection: Universal Traverse Mercator (UTM) Medium: Digital PDF download.

This map is part of the AUSTopo - Australian Digital Topographic Map Series. It covers the whole of Australia at a scale of 1:250 000 (1cm on a map represents 2.5 km on the ground) and comprises 516 maps. This is the largest scale at which published topographic maps cover the entire continent. Each standard map covers an area of approximately 1.5 degrees longitude by 1 degree latitude or about 150 kilometres from east to west and at least 110 kilometres from north to south. The topographic map shows approximate coverage of the sheets. The map may contain information from surrounding map sheets to maximise utilisation of available space on the map sheet. There are about 50 special maps in the series and these maps cover a non-standard area. Typically, where a map produced on standard sheet lines is largely ocean it is combined with its landward neighbour. These maps contain natural and constructed features including road and rail infrastructure, vegetation, hydrography, contours (interval 50m), localities and some administrative boundaries. Coordinates: Geographical and MGA Datum: GDA94, GDA2020, AHD. Projection: Universal Traverse Mercator (UTM) Medium: Digital PDF download.

This map is part of the AUSTopo - Australian Digital Topographic Map Series. It covers the whole of Australia at a scale of 1:250 000 (1cm on a map represents 2.5 km on the ground) and comprises 516 maps. This is the largest scale at which published topographic maps cover the entire continent. Each standard map covers an area of approximately 1.5 degrees longitude by 1 degree latitude or about 150 kilometres from east to west and at least 110 kilometres from north to south. The topographic map shows approximate coverage of the sheets. The map may contain information from surrounding map sheets to maximise utilisation of available space on the map sheet. There are about 50 special maps in the series and these maps cover a non-standard area. Typically, where a map produced on standard sheet lines is largely ocean it is combined with its landward neighbour. These maps contain natural and constructed features including road and rail infrastructure, vegetation, hydrography, contours (interval 50m), localities and some administrative boundaries. Coordinates: Geographical and MGA Datum: GDA94, GDA2020, AHD. Projection: Universal Traverse Mercator (UTM) Medium: Digital PDF download.

Geoscience Australia’s geomagnetic observatory network covers one-eighth of the Earth. The first Australian geomagnetic observatory was established in 1840 in Hobart. 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, and 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. Geomagnetic storm events across three decades have been analysed to develop a statistical model of geomagnetic storm activity in Australia and the model used to predict the intensity of geomagnetically induced currents in Australia's modern-day power grids. Modelling shows the induced electric fields in South Australia, Victoria and New South Wales caused by an intense magnetic storm that occurred in 1989. Real-time forecasting of geomagnetic hazards using Geoscience Australia’s geomagnetic observatory network and magnetotelluric data from the Australian Lithospheric Architecture Mapping Project helps develop national strategies and risk assessment procedures to mitigate space weather hazard. Abstract submitted to/ presented at 2021 Australasian Exploration Geoscience Conference -AEGC2021 (https://2021.aegc.com.au/).

There are a number of global initiatives to understand and mitigate the impacts of extreme space weather on critical infrastructure and modern society. This paper provides the results of an analysis to estimate extreme geoelectric field values for the Australian region to facilitate evaluation of Australia's power system response to extreme geomagnetic storms. Geoelectric fields are calculated using a grid of modeled magnetotelluric impedance tensors obtained from a 3‐D conductivity model of the Australian region. Statistical metrics derived from grids of geoelectric field time series are analyzed as a function of Dst index for different storm days to extrapolate geoelectric fields to extreme storm levels over a range of ground conductivity conditions. For Carrington event storm levels, geoelectric field values of 5.3 ± 3.8 V/km in the north‐south direction and 9.6 ± 4.3 V/km in the east-west direction are expected for areas of electrically resistive rocks near coastlines that are adjacent to deep highly conductive oceans, and inland, where there are large contrasts between the electrical conductivities of different rock types across Australia. Further, geoelectric field values may change by at least an order of magnitude over the grid spacing interval of 50 km in these areas. The results of the analysis also suggest that upscaling grids of geoelectric field time series derived from an observed storm by the ratio of extreme storm Dst to the observed storm Dst are a valid approach for the Australian region that provides extreme storm scenarios for different storm morphologies. <b>Citation:</b> Marshall, R., Dziura, L., Wang, L., Young, J., & Terkildsen, M. (2020). Estimating extreme geoelectric field values for the Australian region. <i>Space Weather</i>, 18, e2020SW002512. https://doi.org/10.1029/2020SW002512