Hazards/Geomagnetic Disturbance
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Geomagnetic Disturbance
Geomagnetic disturbances are variations in the Earth's magnetic field caused by solar activity, primarily coronal mass ejections. These disturbances induce electric fields at the Earth's surface that drive quasi-dc geomagnetically induced currents through grounded conductors, including transmission lines and transformer neutrals. GIC-driven transformer saturation can cause widespread reactive power absorption, voltage instability, and cascading grid disturbances that threaten offsite power availability to nuclear plants.
MORE INFO COMING SOON — This page is under active development. Detailed content will be available in an upcoming update to the External Hazards Knowledge System.
Return to Hazards. | EPRI technical point of contact: Chris Rochon (CRochon@epri.com)
Date last reviewed: 2026-05-07