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How do geomagnetic storms create voltage surges in power lines and other long conductors?

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Diagram of Earth's atmosphere layers-troposphere, stratosphere, mesosphere, and thermosphere-showing how temperature and air pressure change with increasing altitude, with key features like the ozone layer and pressure percentages at various heights. — Ionosphere and magnetosphere The layers of Earth's atmosphere, with a yellow line showing the air temperature at various heights.

Geomagnetic storms create voltage surges in power lines and other long conductors through the process of electromagnetic induction.123

During a geomagnetic storm, interactions between the solar wind and Earth's magnetosphere trigger intense electrical currents within the ionosphere and magnetosphere. These dynamic current systems cause rapid, localized fluctuations in Earth's geomagnetic field.423

According to Faraday’s law of induction, a changing magnetic field induces an electromotive force (voltage) in any nearby electrical circuit. Because power transmission lines and other long conductors span vast distances, they act as large-scale circuits that intercept these changing magnetic fields. The resulting induced currents can be powerful enough to damage electrical infrastructure, such as transformers, and cause widespread power grid failures.56124