Speaker
Description
Geomagnetically induced currents (GICs) pose a serious risk to technological infrastructures, and their assessment requires reliable estimates of the surface geoelectric field, which depends on the Earth’s subsurface electrical conductivity. Long-period magnetotelluric (MT) surveys are ideal for this purpose, but many broadband MT datasets, originally acquired for geological exploration, remain largely unused for space weather research.
In this study, we explore the feasibility of reusing standard broadband MT data to estimate storm-time geoelectric fields in Southern Italy, a region where such studies have not been conducted before. We analyze several geomagnetic storms from Solar Cycle 25, including the intense “Gannon” storm of May 2024, using data from a broadband MT station (GARG) and 1 Hz magnetic field measurements from the nearby Duronia (DUR) observatory. The local MT response tensor is combined with these magnetic observations to model the surface geoelectric field.
Given the magnetic data sampling rate and MT tensor coverage, we focus on the 2–8000 s period range, which captures most storm-time variations relevant to GIC risk. For validation, we isolate the same frequency band from direct electric field measurements using Empirical Mode Decomposition (EMD). The modelled and observed electric field variations agree closely, demonstrating that archived broadband MT data can accurately capture field components relevant to GIC hazard assessment.
These results showcase the untapped potential of existing MT archives as a cost-effective resource for preliminary space weather hazard evaluation and represent the first application of this approach in Southern Italy.
