The eruption of Iceland's Fagradalsfjall volcano, which began on March 19, 2021 after around 800 years of quiescence, shed light on several mechanisms behind volcano awakening, leading to a better understanding of the processes that occur before and during an eruption.
It has in fact provided the first direct data on the behavior of the Earth's mantle.
This is indicated by two studies, in which several Italian researchers participated, both published in the journal Nature and led by the University of Iceland.
The 2021 event was particularly valuable since the magma did not stop inside the earth's crust before escaping, thus allowing direct information to be collected on the characteristics of the mantle, the layer between the crust and the core from which the magma comes.
"We have known for some time that the Earth's mantle has a very variable chemical composition, a characteristic that is also reflected in the magma erupted during volcanic phenomena", Alessandro Aiuppa, researcher and professor at the University of Palermo, who participated in the Research.
“What we have been able to observe with the Icelandic volcano is that the source of the magma has become deeper during the eruption, thus draining more magma coming from greater depths and therefore enriched with other chemical elements.
This means - continues Aiuppa - that the transitions between the magma sources present in the mantle can occur much faster than previously thought, in the order of a few days ".
The researchers, led for this part of the study by Sæmundur Halldórsson and who also include scholars from the Catania section of the National Institute of Geophysics and Volcanology (Ingv), collected many samples of materials, both solid and gaseous, erupted during the first three months from the beginning of the phenomenon, managing to observe the changes in the chemical composition of the magma 'live'.
“The contribution of the University of Palermo, in particular, was important with regard to gas measurement,” adds the Italian researcher.
"In fact, it was we who supplied the small instruments which, once mounted on drones, allowed the analysis of these compounds, which allowed us to trace the depth from which the magma came".
The second study, led by Freysteinn Sigmundsson, made it possible to study in detail the seismic phenomena that preceded the eruption.
The Icelandic one was initially preceded by an increase in seismic activity and surface deformation of the earth's crust, phenomena which then decreased for several days just before the eruption.
To explain this mechanism, the study authors suggest that forces are stored in the earth's crust when magma is rising: the decline in seismic activity and soil deformation may mean that this process is coming to an end and that magma will erupt. .
The results therefore demonstrate