Details of the abstract
Title of paper |
Towards a new 3D conductivity model of the British Isles: Revisiting MT data from Isle of Skye, Scotland |
List of authors | Montiel-Álvarez, A.M., Hübert, J., Whaler, K.A. |
Affiliation(s) | The University of Edinburgh, British Geological Survey, The University of Edinburgh |
Summary |
Potential ground-level impacts of space weather on infrastructure include so-called Geomagnetically Induced Currents (GICs). These currents result from electromagnetic induction during geomagnetic storms and can damage power networks, pipelines, and railways. Estimating geoelectric fields at the Earth’s surface is a critical element to evaluate the hazard and model GICs. Although the increase in computational capabilities has led to a wide range of GIC estimation techniques, the accurate incorporation of the Earth’s electrical conductivity is probably the least explored aspect. However, large-scale magnetotelluric (MT) surveys are emerging as a suitable way to fill this gap and improve GIC modelling. The SAGE (SWIMMR Activities in Ground Effects) project, led by the British Geological Survey, is one of eleven projects within the UK Strategic Priorities Fund (SPF) Space Weather Instrumentation, Measurement, Modelling, and Risk (SWIMMR) program. As part of the SAGE project, we are acquiring long-period magnetotelluric (LMT) data across Great Britain. These new sites, in addition to legacy datasets, will be used to build a 3D conductivity model of the British Isles. The legacy data include a broadband MT survey in the Isle of Skye that we used as a mini-scale pilot experiment to analyze effects and modelling parameters expected to be crucial in the model of Great Britain (GB). Although the ocean depth is shallow around the Isle of Skye (up to 250m), and in contrast to the argument of negligibility in the previous study, we show that the coast effect is significant. Another aspect related to the coast effect that has been recently investigated is the impact of conductive sediments. We show that adding sediment conductivity variation improves Skye’s model, and we discuss the potential impact on the GB model. Finally, we investigated the effects of varying parameters including resistivity, extension, and cell dimension of the starting model as well as damping and covariance for the 3D inversion. The results from this study not only allowed us to build a new, robust 3D model of the Isle of Skye but set the bases to optimize the future modelling of the British Isles. |
Session Keyword | 3.0 Exploration, Monitoring and Hazards |
File upload |
3.0_towards_a_new_3d_conducti_montiel alvarez.pdf
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