GNGTS 2024 - Atti del 42° Convegno Nazionale

Session 2.1 GNGTS 2024 Statistically interpreting multiple observations derived from one or more geophysical monitoring networks C. Fidani 1,2 ​ 1 Istituto Nazionale di Geofisica e Vulcanologia, Roma, Italy ​ 2 Cenrtral Italy Electromagnetic Network, Fermo, Italy Recent studies have unveiled significant statistical correlations between specific geophysical parameters and seismic activity. Statistical correlations for ULF geomagnetic fluctuations at ground stations have been calculated exclusively when considering moderate magnitude earthquakes (Schekotov et al., 2006). In alternative investigations, a lead time of 6–7 days for Pc1 was observed (Bortnik et al., 2008), VLF noise exhibited a lead time of 2 days (Oike and Yamada, 1994), lightning activities were noted to precede earthquakes by 17–19 days (Liu et al., 2015), and geoelectric fields demonstrated lead times ranging from days to weeks (An et al., 2020). A statistical correlation between earthquakes and VLF/LF signals, spanning approximately 10 years, was established using the Japanese VLF/LF network. The findings, as reported by Hayakawa et al. (2010), disclosed discernible perturbations in the signals occurring 3–6 days before the seismic wave paths. Low-orbit satellites provide the capability to observe extensive ground areas within a few hours, facilitating the monitoring of regions affected by seismic events. From this perspective, using the Intercosmos-24 satellite, Molchanov (1993) observed a 50% increase in the probability of charged particle burst observations occurring 6 to 24 hours before seismic events. Additionally, onboard the AUREOL-3 satellite, Parrot (1994) noted an augmentation in the average wave intensity correlated with seismic activity. The micro-satellite DEMETER enabled a statistical study of VLF electromagnetic wave intensity in the vicinity of earthquake epicenters (Nemec et al., 2008), evidencing a significant decrease in the measured wave intensity, 0–4 h before strong earthquakes. Analysing Total Electron Content (TEC) data from the global ionosphere map, researchers found that the highest occurrence rates of anomalies were associated with earthquakes of larger magnitudes and lower depths, 1–5 days before the seismic events (Zhu et al., 2018). This trend was corroborated by studies conducted in Japan (Kon et al., 2011) and China (Ke et al., 2016). Reports worldwide have documented concentrations of electron density and magnetic anomalies occurring more than two months to a few days before earthquake events (De Santis et al., 2019). Space-based observations have detected thermal infrared anomalies, and a comprehensive review by Tramutoli et al. (2015) has documented the major contributions and results achieved in over 30 years of correlating these anomalies with strong earthquakes. Finally, sudden variations in high-energy charged particles