Analysis of the Geomagnetic Storm of May 2024 at Ebre and Livingston Island Observatories and of the GICs Generated in the Spanish Power Transmission Grid

Abstract

This study analyzes the 10–12 May 2024 geomagnetic storm using data from the Ebre (Spain) and Livingston Island (Antarctica) geomagnetic observatories, together with modeling approaches to assess its impact on the Spanish power transmission grid. Geomagnetic field variations reveal stronger disturbances at higher geomagnetic latitudes, with peak rates of change of the horizontal magnetic field reaching 230.1 nT/min at Livingston Island and 74.4 nT/min at Ebre. A statistical analysis based on a 46‐year data set (1980–2025) indicates that the storm corresponds to a return period of approximately 7.7 years at Ebre, ranking ninth in magnitude. In terms of geoelectric field intensity, the event is less extreme, with a return period of 3.3 years, indicating that it was significant but moderate compared with historical extremes. To evaluate geomagnetically induced currents (GICs), recorded geomagnetic field was combined with a 3D lithospheric resistivity model to estimate geoelectric fields and resulting currents across the Spanish power grid. Results show an uneven GIC distribution, with maximum modeled values reaching 28.7 A, largely due to the alignment of transmission lines with the dominant electric field direction. Model performance was assessed using indirect GIC measurements, revealing a systematic overestimation of observed values. After applying the derived scaling factor to the most vulnerable substation, the expected GIC was estimated at 14.5 ± 3.5 A. The findings confirm that the storm generated measurable GICs in Spain, although they did not pose a risk to the Spanish grid, unlike those recorded in grids at higher latitudes.