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 behavior in Campi Flegrei caldera”, created by a team of researchers fromNational Institute of Geophysics and Volcanology (INGV) in collaboration with the 'University of Campania Luigi Vanvitelli, and published in the scientific journal 'Communications Earth & Environment' by Nature.
The Campi Flegrei, a well-known collapsed caldera to the west of the city of Naples, have a central part that continues to slowly rise and fall in the phenomenon called "bradyseism". This ground movement is accompanied by earthquakes which cause concern.
“The objective 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 to which it is subjected and its temperature influence the relationship between the number total number of earthquakes and their magnitudes, known as the Gutenberg-Richter relationship, in order to identify seismogenic areas with different behaviors and to monitor any changes in behavior over time. The parameter analyzed is called b-value and depends on the ratio between the number of earthquakes of high magnitude and those of smaller magnitude. For example, the value of b equal to 1, observed by analyzing the global seismic catalog, indicates that for every earthquake of magnitude 4, 10 earthquakes of magnitude 3 are observed.
“The developed method provides for an automatic subdivision of the seismic catalog” claims Prof. Cataldo Godano of the University of Campania Luigi Vanvitelli “allowing an accurate estimate of the spatial variations of the relationship between the earthquake magnitudes".
“By analyzing 7670 seismic events that occurred over 18 years, from January 2005 to October 2023, and detected byINGV Vesuvian Observatory (INGV-OV),” continues Vincenzo Convertito, INGV researcher and co-author of the research, “it was possible to highlight that below 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 earthquakes of low magnitude (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 has been observed on a global scale; that is, the estimated value of b 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 the understanding of volcanic dynamics,” continues Anna Tramelli.
“The research team will continue to improve the technique for automatically monitoring changes in the Gutenberg-Richter relationship, with the aim of applying it in 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.
Link to the study: B value enlightens different rheological behavior in Campi Flegrei caldera
How to quote:
Tramelli, Anna & Convertito, V. & Godano, Cataldo. (2024). b value enlightens different rheological behavior in Campi Flegrei caldera. Communications Earth & Environment. 5. 10.1038/s43247-024-01447-y.
Useful links
The distribution of seismicity was recorded at Campi Flegrei from January 2005 to October 2023
b value map from four points of view.
Model of the Campi Flegrei volcanic system deduced from the b value and from other geophysical tomographies.