A team of researchers from the National Institute of Geophysics and Volcanology (INGV) conducted a study on GIC (Geomagnetically Induced Currents), i.e. electric currents that can be established in the subsoil following a very complex chain of physical processes that is triggered when a coronal mass ejection occurs on the Sun, giving rise, for example, to a geomagnetic storm. Under certain conditions, these currents can cause damage to electrical network equipment, causing malfunctions or even blackouts.
The American Geophysical Union's online magazine “Earth and Space News” (EOS) gave the spotlight (Link) to this work in which a preliminary estimate of the risk to which the Italian electricity grid is subject following the establishment of the GICs is made.
About 20 years of data from the magnetic observatories managed by INGV were analyzed in the study and a GIC risk index was calculated. It emerged that, in the time interval considered, only one geomagnetic storm, that of 29 October 2003, produced a level of risk considered "moderate", which is equivalent to a 35 - 65% probability that damage or malfunctions may occur on the net.
The study carried out, however, is to be considered preliminary since there are still numerous unknown factors that need to be evaluated in more detail such as, for example: a) the effects of the electrical conductivity of the soil, especially in coastal regions, where the presence of the sea can intensify the risk of GIC; b) the specific technical characteristics of the Italian network, its state of wear and tear and the protections already operating in the junction cabins; c) the history of network failures as a function of magnetic activity, necessary to be able to better calibrate the risk index.
The countries most at risk of damage due to GICs are those at high latitudes, from 55-60°N up (or 55-60°S down) and, even at these latitudes, only in a few cases intense geomagnetic storms have caused extensive damage.
The most striking case was certainly the blackout that occurred in the Canadian region of Quebec in 1989, when millions of people were left in the dark for days following a strong magnetic storm which caused the breakage of some of the crucial transformers for the operation of the entire network.
At our latitudes, only extreme events, i.e. magnetic storms of extraordinary intensity, are expected to cause potentially harmful GICs but the probability that events of this intensity will occur is extremely low. However it is very important, even for mid-latitude countries, such as Italy, to have a risk estimate from the GIC.
#INGV #EOS #GIC #geomagnetism