The underground waters of the Apennines can oscillate in response to distant earthquakes, which even occur on other continents: this is demonstrated by the anomalous variations in the level of an aquifer in Popoli, in Abruzzo, monitored for five years by researchers from the Sapienza University of Rome in collaboration with the National Institute of Geophysics and Volcanology (Ingv) and the National Research Council (Cnr).
The results of the study, published in Scientific Reports, represent a further step towards a possible future identification of precursor signals to earthquakes in the waters.
In recent years, many studies have highlighted the existence of a link between earthquakes and variations in groundwater circulation, but what is not yet clear is how this phenomenon also concerns 'telesisms', or distant earthquakes, which occurred in other continents, the effects of which are felt thousands of kilometers from the epicenter.
To shed light on the issue is precisely the study of the Popoli aquifer: during the five years of monitoring the signs left by seismic events occurred in the immediate vicinity, but also 18 strong oscillations in response to earthquakes of magnitude greater than 6.5 were identified. occurred all over the world, even over 18,000 kilometers away.
The data also show a correlation between the distance of the earthquake and its magnitude with the extent of the oscillation of the water table.
"From the hydrogeological and seismic investigation it emerged that the seismic waves responsible for the perturbations are the Rayleigh waves that travel on the earth's surface, reaching enormous distances", explains Carlo Doglioni della Sapienza and president Ingv.
"Now that we have identified the perturbations caused by distant earthquakes - specifies the expert - we have an extra tool to distinguish them from the precursor signals induced by nearby earthquakes".
