Traces of a Violent Geomagnetic Storm in Fossil Tree Trunks

Over 14,000 years ago, a geomagnetic storm occurred that was so powerful that it would cause a global blackout today: it occurred in 12,350 BC and its signs have been discovered inside the trunks of fossilized trees . The study led by Kseniia Golubenko of the University of Oulu in Finland and published in the journal Earth and Planetary Science Letters identified them and reconstructed their extent.

"Today, an event like the one described above would have a catastrophic impact , this is because we are a society based on space technologies that are very exposed to events of this type . A good part of the satellites would be 'swept away' , they would stop being operational, from telecommunications to location services, and then there would be a risk of electrical blackouts ", explains Mauro Messerotti, professor of Space Meteorology at the University of Trieste, to ANSA.

The geomagnetic storm of which traces have been discovered is part of the so-called Miyake Events , named after the Japanese physicist Fusa Miyake who was the first to discover the signs of a very violent geomagnetic storm that occurred between 774 and 775 AD . It was identified thanks to a peak in the concentration of carbon-14 in the growth rings of some Japanese cedars. Over time , 5 other events of this severity have been discovered, but the one that occurred 14,000 years ago would have been by far the most powerful. In this case, the memory of it was kept by some Scots pines along the banks of the Drouzet River in France, whose data were also confirmed by some peaks of beryllium-10 in ice cores from Greenland .

The impact of energetic particles expelled by the Sun with the atmosphere leads to the production of cascades of other particles and the formation of some isotopes , i.e. variants with a different number of neutrons, of beryllium and carbon well above average . Isotopes that are then distributed in the atmosphere and absorbed by trees. “These data clearly tell us that such violent storms are not that rare ,” adds Messerotti. “We prefer to think that such events cannot happen to us, but this could be a serious mistake. Only by continuing to study them in depth will we be able to understand them better, so much so that perhaps one day it will be possible to make more accurate predictions and identify strategies to mitigate the dangers.”