A massive coronal mass ejection (CME)—commonly known as a solar storm—in July 2012 could have rivaled the worst recorded event from 1859 had it hit the Earth, according to a study published Mar. 18 in Nature Communications.
Research at the University of California, Berkeley, and by Chinese scientists into a magnetic storm on July 23, 2012, determined that the unusually large event propelled magnetic material from the sun outward at a peak speed of more than 2,000 km/hr, four times faster than typical magnetic storms. The burst resulted from at least two CMEs about ten minutes apart, and its high speed occurred because another event four days earlier cleared the path of material that would have slowed it down.
Worse, it produced a very long duration southward-oriented magnetic field that would have collided violently with the Earth’s northward-oriented field had it hit. While most CMEs release their energy at the poles—causing the well-known aurora borealis and aurora australis effects—such an event would have released its energy around the globe.
Fortunately, the storm erupted on a side of the sun that was oriented away from the Earth at the time. Had it come nine days earlier, however, it would have been aimed directly at us.
The researchers estimated that the effect could have rivaled the 1859 Carrington event as the worst magnetic storm in recorded history. That storm damaged telegraph systems around the world, in some cases delivering electric shocks to operators and starting fires. The damage from a similar event today would likely be several orders of magnitude worse.
CMEs are dangerous to electrical equipment because they can produce geomagnetically induced currents on the Earth’s surface. Among other effects, these currents can enter the electrical grid and cause wild voltage fluctuations, damaging transformers and starting fires. A much smaller CME in 1989 wreaked havoc across Canada, tripping Hydro-Québec’s La Grande high-voltage transmission network and causing widespread power outages and damage up and down the U.S. East Coast.
2012 was predicted to be a year of strong solar storms, and authorities have been warning for years that the electrical grid is badly unprepared for another event on the scale of 1989, let alone 1859. Estimates of the damage from another 1859 event have run into trillions of dollars worldwide.
Last year, the Federal Energy Regulatory Commission (FERC) ordered the North American Electric Reliability Corp. to develop reliability standards that address the impact of geomagnetic disturbances on the bulk power system. Those standards are now being reviewed by FERC, and will require equipment operators to develop strategies to limit the impact of CMEs and upgrade equipment as necessary.
—Thomas W. Overton, JD is a POWER associate editor (@thomas_overton, @POWERmagazine).