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/).

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/)