With a statistical study, the concentrations of electromagnetic anomalies in the ionosphere before strong earthquakes have been correlated
A statistically significant determination of electromagnetic anomaly concentrations in the ionosphere prior to the occurrence of earthquakes of magnitude 5.5 or greater, and with hypocentral depths up to 50 km.
This is the most important result of the study "Precursory worldwide signatures of earthquake occurrences on Swarm satellite data" by an interdisciplinary group of researchers from the National Institute of Geophysics and Volcanology (INGV), Planetek Italia srl and the European Space Agency (ESA) just published in the prestigious journal Scientific Reports of the Nature publishing group.
Thanks to the financial support given by ESA to the SAFE project (SwArm For Earthquake study), the team led by INGV analyzed the magnetic and plasma data in the ionosphere - the ionized layer of the upper atmosphere - measured at an altitude of about 500 km by the three satellites of the "Swarm" project, the ESA mission created to improve knowledge of the earth's magnetic field.
Going beyond the scope of the Swarm mission itself, the research group looked for "electromagnetic" traces of coupling with the Earth's lithosphere during large earthquakes.
The main result of the research was a statistically significant identification of concentrations of electromagnetic anomalies in the ionosphere before the occurrence of earthquakes of magnitude equal to 5.5 or greater, and with a hypocentral depth up to 50km.
“The importance of this work is twofold” – underlines Angelo De Santis, Research Director of INGV and first author of the article. “On the one hand, we were able to statistically confirm that, during the preparatory phase of a major earthquake, there is a coupling between the lithosphere, where earthquakes occur, and the overlying ionosphere. In another respect, then, Rikitake's empirical law has been confirmed with satellite data. This is a law proposed in the 80s for precursors on the ground, according to which the advance time of the precursors depends on the magnitude of the earthquake: the longer the advance time of the precursor, the stronger the earthquake will be”.
"The result of our work is very important" concludes De Santis "but although the anomalies identified are statistically linked to the occurrence of earthquakes, they still do not allow us to make forecasts of seismic events, for which it is necessary to pass from a statistical approach to a deterministic one, which will require further study in the future."
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