Scientists say aurora, caused by head-on collisions with Earth’s magnetic field, could damage critical infrastructure

Auroras have inspired myths and omens for millennia, but only now, with modern technology that relies on electricity, do we appreciate their true power. The same forces that cause auroras also generate currents that can damage infrastructure that carries electricity, such as pipelines.

Now scientists are writing in Frontiers in astronomy and space sciences have shown that the impact angle of interplanetary shocks determines the strength of the currents. This offers the possibility to predict dangerous shocks and shield critical infrastructure.

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

“The auroral region can expand dramatically during severe geomagnetic storms,” ​​he added. “Normally, its southernmost limit is around 70 degrees latitude, but during extreme events it can drop to 40 degrees or even further, which is certainly what happened during the May 2024 storm – the most severe storm in the past two decades.”

Lights, color, action

The aurora is created by two processes: particles emitted by the sun collide with the Earth’s magnetic field, causing a geomagnetic storm, or interplanetary shocks compress the Earth’s magnetic field.

These shocks also generate geomagnetically induced currents, which 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 significant damaging impact on the electrical infrastructure occurred in March 1989, following a severe geomagnetic storm. The Hydro-Quebec system in Canada was down for nearly nine hours, leaving millions of people without electricity,” Oliveira said.

“But weaker, more frequent events such as interplanetary shocks could eventually pose a threat to Earth’s conductors. Our work shows that significant geoelectric currents occur quite often after shocks, and that these deserve attention.”

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

To do this, they took a database of interplanetary shocks and compared it with measurements of geomagnetically induced currents from a natural gas pipeline in Mäntsälä, Finland, which is typically located in the auroral region during active periods.

To calculate the properties of these shocks, such as angle and velocity, they used interplanetary magnetic field and solar wind data. The shocks were divided into three groups: highly inclined shocks, moderately inclined shocks, and near-frontal shocks.

Angle of attack

They found that more frontal shocks cause higher peaks 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 have been between the sun and Mäntsälä. Local substorms at this time also cause striking brightening of the aurora.

“Moderate currents occur shortly after the disturbance, around sunset local time in Mäntsälä, while more intense currents occur around midnight local time,” Oliveira said.

Because the angles of these shocks can be predicted up to two hours before impact, this information allows us to take protective measures for power grids and other vulnerable infrastructure before the strongest and most frontal shocks occur.

“One thing that electric infrastructure operators can do to protect their equipment is to control a few specific electrical circuits when a shock alarm is triggered,” Oliveira suggested. “This would prevent geomagnetically induced currents from shortening the life of the equipment.”

However, the scientists did not find strong correlations between the angle of a shock and the time it takes for the shock to hit and then induce a current. This may be because more current recordings at different latitudes are needed to investigate this aspect.

“The current data has only been collected at one specific location, namely the Mäntsälä natural gas pipeline system,” Oliveira warned.

“Although Mäntsälä is located in a critical location, it does not provide a global picture. In addition, there are several days missing from the Mäntsälä data during the period under investigation, which meant that we had to remove many events from our shock database. It would be great if global energy companies would make their data accessible to scientists for studies.”