New analyses define the possible evolution of bradyseism in the Phlegraean area in the next decades, specifying that the current conditions of the volcano would not be capable of generating an eruption
Thanks to the use of thermal and petrological models, a study just published in the journal “Communications Earth and Environment” Nature has proposed a reference scenario to determine whether or not the Campi Flegrei could give rise to an eruption. The work, edited by a team of researchers from theNational Institute of Geophysics and Volcanology (INGV) and University of Geneva (Switzerland), has allowed us to develop a model based on what Anglo-Saxon literature defines as “the worst case”, the worst case.
The study, entitled “Scenario-based forecast of the evolution of 75 years of unrest at Campi Flegrei caldera (Italy)”, is based on the assumption that the current bradyseism in progress since 2005, as well as that recorded in the years 1950, 1970-1972 and 1982-1984, is determined by successive intrusions of magma at depths of about 4 kilometers.
"We chose to start from this assumption because it is the most precautionary one for the inhabitants of the Phlegraean area subject to volcanic danger and allows, at least, to define a possible evolutionary scenario.", explains Stefano Carlino, researcher at INGV and co-author of the study.
“Our calculations suggest that, although potentially eruptible magma could be present at about 4 kilometers depth and the overpressure within the magma reservoir could be sufficient to fracture the surrounding crust, an eruption would be hindered by the combination of several factors, including the small volume of the magma reservoir and the viscous deformation of the surrounding crust,” he adds. Luca Caricchi, full professor at the University of Geneva and co-author of the work.
“The reduced volume of the magma reservoir, in particular, currently represents one of the major obstacles to the eruption, since any possible release of magma from it would cause a sudden drop in internal pressure which, in turn, would not provide the magma with sufficient energy to reach the surface.”, they continue Charline Lormand e Guy Simpson of the University of Geneva, co-authors of the study.
If the current ground uplift dynamics in the Phlegraean Fields area were to continue in the future at rates similar to those of today, the magma source generating the uplift could reach, in a few decades, a size suitable for generating an eruption, with an accumulation of magma volumes comparable to that which fueled the last eruptive event of the Phlegraean Fields in 1538.
“However, as mentioned, the results of our study derive from the assumption that the bradyseism of the last 75 years, therefore the uplift of the ground, was fed by the rising deep magma and, in part, by the fluids that escaped from it: this is a possible condition, but not easy to verify., reiterates Stefano CarlinoFurthermore, it is important to underline that although previous studies have highlighted numerous fractures in the Campi Flegrei crust, the current conditions are not suitable for an eruptive event., he specifies Thomas Pivetta, researcher at INGV and co-author of the article.
To try to mitigate the difficulty in predicting how the volcano will behave in the future, scientific research efforts in this field remain focused on determining, through geophysical, geochemical, and geodetic measurements and through the joint study and processing of data, the true nature of the source of the bradyseism, currently still the subject of scientific debate.
Link to the studyUseful links: https://www.ingv.it/
University of Geneva
Figure: Temporal evolution of magma volume and excess fluids at different temperatures. The figure shows the results for magma injections of a thickness of 25 m, as well as the maximum and minimum volumes of magma injection events. The lower limit of each colored region refers to the calculations performed considering the minimum volume of magma injected in each event. The numbers next to the dashed lines indicate the minimum and maximum volumes of magma injected in each episode. The differently colored bands represent the volumes of excess fluids (in blue and associated with the right y-axis) and magma at different temperatures present in the magma reservoir over time.