Geodetic contribution to predict the seismological activity of the Italian metropolis by the ionospheric variant of GPS_TEC

Abstract

In this paper, we present a predictive approach treating the seismic hazard to detect, through to the geodetic data and the ionospheric total electron content (TEC) Anomalies, the time-origin of the seismic precursors of notable earthquakes (Mw ≥ 5). The main aim of this paper is to show the geo-spatial investigation interest to establish the ionospheric ‘TEC-Mapping’ allowing the monitoring and prediction of spontaneous vibrations of the lithospheric layer. For this purpose, we studied the seismic events that rocked the Italian peninsula (Central Italy, Mw > 6.1, late October 2016), where several IGS geodetic stations surrounding the hypocenter, were exploited to acquire raw data allowing to reconstitute in real time the GPS_TEC signal. As results, the elaborated ‘TEC’ diagram has allowed us to observe significant disturbances in the ionospheric TEC's amplitudes appear near the epicenter, a few days, before the Central Italy earthquake; which are related to the fluctuations of the electron density of the surrounding ionosphere. These anomalies represent the early percussion of seismic vibrations on earth, which truly respond the ternary coupling: Lithosphere-Atmosphere-Ionosphere. We also studied the causes that can disturb the ionosphere in order to distinguish from the pre-earthquake precursors. Finally, we confirmed the efficacy of this geodetic approach, applied in the natural hazards area, which can contribute effectively to the prediction of a significant seismic event in a given region.