Identified several seismic structures within the Campi Flegrei caldera through the analysis of the distribution of earthquake magnitudes in space.
Understand how the characteristics of the earth's crust at the Campi Flegrei caldera, the stress to which it is subjected and the temperatures that characterize it, can influence the number of earthquakes and their magnitudes.
These are the objectives of the innovative study “B value enlightens different rheological behaviour in Campi Flegrei boiler”, created by a team of researchers from the National Institute of Geophysics and Volcanology (INGV) in collaboration with the University of Campania Luigi Vanvitelli, and published in the scientific journal 'Communications Earth & Environment' of Nature.
I Campi Flegrei, a well-known collapsed caldera west of the city of Naples, have a central part that continues to slowly rise and fall in a phenomenon called “bradyseism.” This ground movement is accompanied by earthquakes that cause concern.
"The goal of the research," explains Anna Tramelli, INGV researcher and first author of the study, "was to understand how the characteristics of the crust, the stress it is subjected to, and its temperature influence the relationship between the total number of earthquakes and their magnitudes, known as the Gutenberg-Richter relationship. This will help us identify seismogenic areas with different behaviors and monitor any changes in behavior over time.
The parameter being analyzed is called the b-value and depends on the ratio between the number of high-magnitude earthquakes and those of lower magnitude. For example, a b-value of 1, observed by analyzing the global seismic catalog, indicates that for every magnitude 4 earthquake, 10 magnitude 3 earthquakes are observed.
“The developed method provides for an automatic subdivision of the seismic catalogue” claims Prof.
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“By analyzing 7670 seismic events that occurred over 18 years, from January 2005 to October 2023, and detected by the INGV Vesuvius Observatory (INGV-OV),” continues Vincenzo Convertito, INGV researcher and co-author of the research, “it was possible to highlight that beneath the Solfatara and Pisciarelli areas, up to a depth of approximately 2 km, the high fracturing of the rocks and the presence of hydrothermal fluids favor the occurrence of low-magnitude earthquakes (up to Md = 3) compared to those of higher magnitude (up to Md = 4.4).
Below 2 km, however, for the surrounding areas the relationship between earthquake magnitudes is consistent with what is observed on a global scale; that is, the estimated b value is very close to 1".
The discovery of variations in the relationship between earthquake magnitudes within the Campi Flegrei caldera represents an important step forward for the monitoring of volcanic areas.
“The ability to automatically detect variations in this ratio could significantly improve seismic monitoring and understanding of volcanic dynamics,” continues Anna Tramelli.
“The research team will continue to improve the technique for automatically monitoring variations in the Gutenberg-Richter relation, with the aim of applying it to other volcanic areas and using the results to predict potentially dangerous changes in the dynamics of the Earth's crust,” concludes Vincenzo Convertito.
The published research has an essentially scientific value, currently devoid of immediate implications regarding the aspects of civil protection, representing a potentially useful contribution in the future to refine the forecasting and prevention tools of civil protection. At the moment the research results have no direct implication on measures affecting the safety of the population.
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