Mid-Latitude Geoelectric Field Response in North China During the May 2024 Superstorm: Effects of Geological Heterogeneity

Geoelectric field disturbances during geomagnetic storms pose growing risks to mid-latitude power systems, yet direct observations remain limited. We report multi-station, real-time GIE observations from a new monitoring network in North China, comprising 22 geoelectric and 4 geomagnetic stations. This network captured detailed GIE responses during the May 2024 superstorm, providing rare mid-latitude field measurements under extreme space weather conditions. Although geomagnetic field variations were relatively uniform across the region, the induced geoelectric fields exhibited significant spatial heterogeneity, primarily controlled by local subsurface conductivity. In mountainous regions such as the Qinling orogen, peak GIE amplitudes reached up to 1,500 mV/km—substantially higher than in surrounding basins and plains. Magnetotelluric (MT) impedance analysis reveals pronounced electrical anisotropy beneath these zones, which preferentially amplifies the north–south component of the GIEs. These findings offer key observational evidence linking subsurface structure to storm-time GIE amplification, and have direct implications for GIC forecasting and infrastructure resilience in tectonically complex, mid-latitude regions.