The origin of the bradyseism and the seismicity that affected the Phlegraean Fields in the last 16 years old it should be attributed to a possible magma rising from a depth – relatively superficial – between 4 km and 8 km. This is stated in a study published on September 13, 2024 in the magazine Nature – Communications of Earth and Environmentconducted by researchers from the National Earthquake Observatory and the Vesuvius Observatory of the National Institute of Geophysics and Volcanology (INGV), in collaboration with the University of Roma Tre and the University of Geneva.
Using a multidisciplinary approach which saw the integration of measures radar And satellites from the ground deformationnumerical simulations and petrologic models, the researchers have mapped the changes in the position, size And volume from the source of the bradyseismic crisis of the Campi Flegrei from 2007 to 2023. Since 2005, in fact, the Pozzuoli area has recorded a gradual uplift of the ground, which has reached values equal to 1.3 meters in 2024The uplift rate has not remained constant over the last 16 years, but, on the contrary, has increased from initial values of 1.1 ± 0.4 cm per year until the 2011to 15.9 ± 0.7 centimeters per year between 2022 and 2023. The increase in the rate of ground uplift was accompanied by the‘intensification of seismic swarms and of their magnitudeJust think of the earthquakes of magnitude 3.5 and 4.4 that hit the area on May 20, 2024bringing the Civil Protection alert level yellow.
The new study outlined two springs underground responsible for the surface deformation. The first, which in 2007 was located at a depth of about 5.9 ± 0.6 km, is gradually rise to 3.9 ± 0.2 km in 2023. Its volume has also changed, going from from 0.1 km³ to 0.16 km³, with an increase of approximately 60 million cubic meters in sixteen yearsThe second magmatic source, instead, occupies a surface of approximately 100 km² and is stationary at a depth of approximately 8 km. This deeper source would be the engine of the activity of the Campi Flegrei.
The data indicate, in fact, a reduction of the volume of the deepest source in the period investigated, at a rate of approximately 104–105 m³/yearwhich is opposed to thevolumetric increase of the most superficial sourceequal to 106 m³/year. This reverse trend suggests that the two sources are in communication. In particular, considering various scenarios, the researchers deduced that the source of surface deformation is probably powered by rising magma and gas coming from the main source 8 km away. However, the exact volume of rising magma and gas cannot be precisely defined.
Mauro Antonio DiVitoDirector of the Vesuvius Observatory of the INGV and co-author of the study, underlined the importance of the research, stating: “Although it is not possible to establish with certainty the presence of magma at about 4 km depth, the study demonstrates for the first time that magma, rising from 8 km, is the main driver of the activity underway at Campi Flegrei”.
It should be emphasized, however, that the results of the study they do not indicate an imminent eruption of the Campi Flegrei. The data in fact show similarities with what was observed in the previous 16 years, although highlighting an intensification of the demonstrations. However, as Di Vito added, “the continued accumulation of magma and the increase in pressure underground represent a risk that must not be ignored.”
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