GNGTS 2024 - Atti del 42° Convegno Nazionale

Session 2.1 GNGTS 2024 A year and half later, following the team indications, another three detectors were realized and installed; two in Gubbio and one at the Perugia Seismic Observatory Andrea Bin a https://www.binapg.it/ . The detectors are embedded in a network of observatories and have so far collected continuous recordings, separated by some interruptions due to the need for instrument maintenance, together with electric and magnetic detectors, gamma and air ions detectors, as well as meteorological stations https://cfidani.wixsite.com/cien . The objective of these instruments is to develop a physical model that links earthquake events to mutually interacting geophysical observables, in order to better understand the earthquake process manifested in the lowest surface atmosphere. Thus, for example, Radon escaping from the ground has been widely hypothesized to be driven by fluid migration towards the Earth's surface, and Radon plus fluids entering the atmosphere able to generate electromagnetic signals therein modifying meteorological conditions. Moreover, fluid migrations have been reported to be the primary trigger of Appennine earthquakes (Chiodini et al., 2004). Finally, the multi-parameter monitoring of the Central Italy Electromagnetic Network is mainly dedicated to the physical processes occurring on the ground-atmosphere interface. Two moderately intense seismic events struck Central Italy between November-December 2023. An earthquake of magnitude ML = 4.0 occurred at about 3 km S Montelparo (Fermo), on November 14, 2023, 17:17:50 Italian time with geographical coordinates 42.996N and 13.537E at a depth of 21.6 km. The shock was generated by a compressional fault that is a typical mechanism of this area, due to the Apennine axis relaxation which towards the Adriatic Sea implicates a shortening belt. The area had been characterised by strong seismic events, as confirmed by the strong earthquakes of November 26, 1972, having an estimated magnitude Mw = 5.5, and of October 3, 1943, with an estimated magnitude Mw = 5.7 (INGV, 2015). The hourly decay counts of the 5 days preceding the November 14, 2023 shock are shown with a blue line in Fig. 2 bottom. Whereas, the red line in Fig. 2 bottom represents the 12-hour moving average of 12 previous counts reported in real time. Specifically, two decay increases are better visible by 12-hour moving averages, and these increases anticipated the seismic event indicated by a vertical red arrow in Fig. 2 bottom. The end of the smallest recorded average increase preceded the earthquake by two days, while the end of the largest recorded average increase preceded the earthquake by one day. The increases peak intensities were 30% for the smallest and of 120% for the largest. The meteorological instruments at the Fermo Station did not report any rain events or sudden pressure reductions during the peaks. However, a weak rain event registered prior to the quake was recorded between November 10 th and 11 th , 2023, with a cumulation of 7 mm. These peaks were repeatedly detected before moderate seismic events at the Fermo Station. Furthermore, similar peaks were also detected before moderate seismic events in Central Italy by the stations located in Nepi (VT), Orvieto (TR), Campli (TE), and Gubbio (PG ) http://www.osservatorionovara.it/ . Other peaks and periodic variations having not been followed by moderate seismic events have been studied in relation to meteorological variables providing some interpretative agreement. Additional examples of increases, similar to those recorded a few days after the Montelparo event, occurred without any significant recorded seismic and meteorological events. On November 16, 2023, a sudden increase in the count decay was recorded to be 20 times the average, only to return to the initial value before the end of the same day, see Fig. 2 top. No rain or pressure variation events were recorded by the meteorological instruments before November 16. While a sudden and unexpected temperature