Continuous long-term analysis on earthquake-related Total Electron Content (TEC) signals across the Mediterranean region

CONTINUOUS LONG-TERM ANALYSIS ON EARTHQUAKE-RELATED TOTAL ELECTRON CONTENT (TEC) SIGNALS ACROSS THE MEDITERRANEAN REGION R. Colonna 1,2, C. Filizzola 3,2, N. Genzano 4, N. Pergola 3,2, V. Tramutoli 1,2 1) School of Engineering, University of Basilicata, Potenza, Italy; 2) Satellite Application Centre (SAC), Space Technologies and Applications Centre (STAC), 85100 Potenza, Italy; 3) Institute of Methodologies for Environmental Analysis, National Research Council, Tito Scalo (PZ), Italy; 4) Department ABC (Architecture, Built Environment and Construction Engineering), Politecnico di Milano, Via Ponzio 31, 20133 Milano, Italy; In recent years, the integration of extensive historical satellite records with rapid advancements in artificial intelligence techniques has significantly enhanced the study of space-based detection of seismic-related anomalies. Over the past decade, various geophysical parameters—including electromagnetic field components across diverse frequency ranges, Earth's thermal emissions, ground-level gas discharges, and ionospheric characteristics—have been proposed as potential precursors to seismic activity. Specifically, the analysis of Total Electron Content (TEC) variations has been extensively explored as a potential indicator of ionospheric disturbances linked to seismic events. A comprehensive, systematic, and continuous examination of long-term historical data is crucial to distinguish between TEC fluctuations resulting from natural ionospheric cycles and those induced by non-terrestrial factors, both of which are heavily influenced by solar activity. In this study, multi-year GNSS-derived TEC datasets are correlated with extended time series of seismic events across the Mediterranean region and analyzed using an interquartile range (IQR)–based methodology. The findings reveal a non-random correlation between the most intense TEC anomalies detected in the multi-year time series and the occurrence of significant seismic events. These results are discussed in the context of evaluating the potential for developing and deploying a TEC-integrated multi-parametric system for time-dependent assessment of seismic hazard (t-DASH).