Auroras from head-on hits to Earth’s magnetic field could damage critical infrastructure, scientists say

The aurora borealis has inspired myths and omens for millennia – but only now, with modern technology dependent on electricity, do we appreciate their true power. The same forces that cause the aurora borealis also cause currents that can damage infrastructure that conducts electricity, such as pipelines.

Now scientists write Frontiers in Astronomy and Space Sciences demonstrated that the angle of incidence of interplanetary shocks is key to the strength of currents and offers an opportunity to predict dangerous shocks and protect critical infrastructure.

“Auroras and geomagnetically induced currents are caused by similar drivers of space weather,” explained Dr. Denny Oliveira of NASA’s Goddard Space Flight Center, lead author of the paper. “The aurora borealis is a visual warning that suggests that electrical currents in space can generate these geomagnetically induced currents on earth.”

“The polar region can expand considerably during strong geomagnetic storms,” ​​he added. “Usually its southernmost limit is around 70 degrees latitude, but during extreme events it can drop to 40 degrees or more, which certainly happened during the May 2024 storm – the most severe storm in two decades.”

Lights, colors, action

Auroras are caused by two processes: either particles ejected from the Sun reach the Earth’s magnetic field and cause a geomagnetic storm, or interplanetary shocks compress the Earth’s magnetic field.

These tremors also generate geomagnetically induced currents that can damage infrastructure that conducts electricity. Stronger interplanetary shocks mean stronger currents and auroras—but frequent, less powerful shocks can also cause damage.

“Probably the most intense damaging effects on energy infrastructure occurred in March 1989 after a severe geomagnetic storm – the Hydro-Quebec system in Canada was shut down for nearly nine hours, leaving millions without electricity,” Oliveira said.

“But weaker, more frequent events, such as interplanetary tremors, can pose a threat to grounding conductors over time. Our work shows that aftershocks, significant geoelectric currents occur quite often and deserve attention.”

Shocks that hit the Earth head-on, rather than at an angle, are thought to produce stronger geomagnetically induced currents because they compress the magnetic field more. The researchers investigated how geomagnetically induced currents are affected by tremors at different angles and times of day.

To do this, they took a database of interplanetary tremors and compared it with data on geomagnetically induced currents from a pipeline in Mäntsälä, Finland, which is usually located in the polar region during active times.

They used data on the interplanetary magnetic field and solar wind to calculate the properties of these shocks, such as angle and speed. The shocks were divided into three groups: high-tilt shocks, slightly inclined shocks, and near-head shocks.

Angle of attack

They found that more foreshocks cause higher spikes in geomagnetically induced currents both immediately after the shock and during the subsequent substorm. Particularly intense peaks occurred around magnetic midnight, when the North Pole would be between the Sun and Mäntsälä. Localized substorms at this time also cause significant brightening of the aurora borealis.

“Medium currents appear shortly after the impact of the disturbance when Mäntsälä is around dusk local time, while more intense currents occur around midnight local time,” Oliveira said.

Since the angles of these shocks can be predicted up to two hours before impact, this information could allow us to set up protections for power grids and other vulnerable infrastructure before the strongest and most frontal shocks hit.

“One thing that energy infrastructure operators could do to protect their facilities is to control a few specific electrical circuits when a shock warning is issued,” Oliveira suggested. “This would prevent geomagnetically induced currents from shortening the lifetime of the device.”

However, the researchers did not find a strong correlation between the angle of the shock and the time it takes to strike and then generate a current. This may be because more current records at different latitudes are needed to investigate this aspect.

“Current data has only been collected at a specific location, namely the Mäntsälä pipeline system,” Oliveira warned.

“Although Mäntsälä is in a critical location, it does not provide a global picture. In addition, data from Mäntsälä are missing several days in the study period, which forced us to discard many events in our shock database. It would be nice to have global energy companies make their data available for scientists to study.”