A new scientific study has examined the seismicity that occurred in the Campi Flegrei caldera, one of the most monitored volcanic areas in the world, known for its complex bradyseismic dynamics
Since 2005, the Campi Flegrei have been subject to a new bradyseismic phase, which is still ongoing.
With the study “Space and time distribution of seismic source energy at Campi Flegrei, Italy through the last unrest phase (1.1.2000–31.12.2023)” just published in the international journal 'Physics of the Earth and Planetary Interiors', the researchers of theIstituto Nazionale di Geofisica e Vulcanologia (INGV) analyzed a significant dataset on the spatio-temporal variations of seismic parameters, acquired between January 1, 2000, and December 31, 2023, with the aim of better understanding the phenomena characterizing the current volcanic crisis.
The research highlighted that the spatial and temporal distribution of earthquakes occurs mainly in swarms, with an average duration of about one day for each swarm.
Edoardo Del Pezzo, research associate at the Vesuvius Observatory of the INGV and first author of the study, specifies “Since 2010 we have observed an increase in the number of swarms and events within each of them, suggesting an evolution of the seismic activity of the caldera. However, we have not detected a significant increase in the total seismic moment, or energy released, within each swarm over time”.
An innovative aspect of the study concerned the analysis of the spatial density of seismic energy.
Francesca Bianco, Director of the INGV Volcanoes Department and co-author of the study, specifies “In the last 15 months - from October 2022 to December 2023 - an expansion of the fracture zones has been detected in the western part of the caldera, at a depth of about 3000 meters below sea level. This area of greater fracturing coincides with areas characterized by strong contrasts in seismic attenuation, suggesting intense rock deformation activity. The distribution of the spatial density of seismic energy, together with the statistical study of the temporal distribution of earthquakes, highlight important properties of bradyseism, confirming that the instability phase of the Campi Flegrei is still ongoing, with a progressive expansion of the fracture zones towards the south and west compared to measurements taken 22 months earlier, from December 2020 to October 2022”.
This study suggests the usefulness of continuous monitoring of the spatial density parameter of seismic energy, together with the classical spatial distribution of hypocenters.
The latter, in fact, in the case of numerous events in relatively small volumes, does not allow an immediate vision of the real energy at play, which is instead a crucial parameter for understanding the evolution of the ongoing bradyseismic crisis and for contributing to defining possible evolutionary scenarios of the volcanic phenomenon.
The research is part of the many ongoing projects aimed at understanding the fascinating phenomenon of Phlegraean bradyseism, important not only for scientific reasons but also for the enormous social impact of a possible eruption in the area.
How to quote:
Edoardo Del Pezzo, Francesca Bianco, Space and time distribution of seismic source energy at Campi Flegrei, Italy through the last unrest phase (1.1.2000–31.12.2023), Physics of the Earth and Planetary Interiors, Volume 356, 2024, 107258, ISSN 0031-9201, https://doi.org/10.1016/j.pepi.2024.107258
Link to the study:
Useful links:
The Campi Flegrei map shows earthquakes above magnitude 1.5 with circles proportional to the magnitude. The panels on the right show the hypocenter projections on the north-south and east-west planes.rw
On the left, three vertical sections (located in the green strip of the map at the bottom right) showing the ESD in different time periods. On the right, the three-dimensional image showing the ESD in the time interval 2000-2023