Earth’s magnetic field is quieting, finally, almost 48 hours after a surprisingly strong geomagnetic storm sparked auroras seen from the Arctic Circle to the continental USA. And during the surprisingly strong G3-class geomagnetic storm of Aug. 26th, there was action underground as well. Strong electric currents moving through the soils have been detected in the ground of Norway, which were about 10 times stronger than normal. Let’s just say that’s a pretty rare during solar minimum!
When a geomagnetic storm erupts, most eyes naturally turn to the sky, looking for auroras.
But during the strong G3-class geomagnetic storm of Aug. 26, 2018, there was action underfoot as well. Probes buried in the ground in Norway detected strong currents of electricity moving through the soil.
The currents were remarkably strong. During the magnetic storm, voltages surged to 10mv/m or 10v/km. That’s about 10 times stronger than normal. These are pretty rare readings without a strong solar flare during solar minimum.
Why does electricity flow through the ground during a geomagnetic storm?
Changing magnetic fields cause currents to flow in wires and other conductors. In most places, soil can conduct electricity due to the presence of dissolved salts and minerals. So when the local magnetic field begins to vibrate, electricity naturally begins to flow. Currents induced by geomagnetic storms can cause voltage fluctuations in power systems and in rare cases complete blackouts.
Arctic sky watchers should remain alert for auroras. Earth is passing through a stream of high-speed solar wind, and there is a 40% chance of renewed minor storms on Aug. 28th.