Geoelectric map of US to protect power grid from space weather

A mapping of the electrical properties of the Earth’s crust and mantle across the US is expected to aid protection of the power grid from extreme ‘space weather’ events.

The mapping, an almost twenty-year effort by Oregon State University researchers, is expected to enable power companies and others to better understand how naturally occurring ‘space weather’ induced geomagnetic sub-surface currents and other electromagnetic phenomena interface with the power grid.

Such geomagnetic disturbances, which are induced by solar activity such as flares and coronal mass ejections, have long been known to impact the Earth, for example causing the Northern lights and effects such as radio communication interference.

They also impact the power grids, particularly in the high latitude countries – a notable example being the March 1989 blackout on Hydro-Québec’s grid – but it is an area that remains little studied.

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“Before, we had a patchwork quilt of information but we could not connect the dots. Now we can see the entire picture,” said Adam Schultz, a professor in Oregon State University’s College of Earth, Ocean, and Atmospheric Sciences and the principal investigator of the project.

Noting that in May the Earth experienced its strongest solar storm in more than 30 years, causing power grid irregularities and problems with GPS systems, as well as affecting radio and some cellular phone service, he continued. “We didn’t see any wide-scale power issues during that storm and the power industry had access to the data we have provided through this effort, so that’s an indication of the project’s success.

“This is vital information that helps tell them how geomagnetic currents will interface with electrical substations.”

The initiative to measure and map the electrical conductivity of the Earth had its origins in 2006 with the ‘Magnetotelleric array’ project to collect information about the structure and evolution of the North American continent.

Starting in eastern Oregon, researchers deployed instruments across a grid every 70km or so to survey the electromagnetic energy below the surface.

But as the data started to be gathered, the realisation grew that it could be used for other applications including identifying geological hazards, areas for geothermal power exploration and sites for exploration of critical minerals, as well as mitigating the impacts of space weather – an outcome of which was the provision from NASA of funding towards the mapping.

The final map, which was completed in June, covers the entire US from the Earth’s surface through the crust and mantle to a depth of 300km.

As an example of a geological finding, a sharp transition in the structure of the Earth’s crust was found running along the East Coast from Washington, DC to Georgia, which can greatly amplify the geomagnetically induced currents and puts the area at higher risk in a big geomagnetic storm.

Additional research is needed in such high hazard areas to obtain higher resolution records of the structure in order to better understand the implications.