Radio Direction Finding System Applied to Identify Pre-seismic Signals in the Adriatic Sea

In this study, we present the application of a multiparameter analysis for the search of seismic precursor candidates, tested with a deterministic approach. The seismic sequence analyzed concerns the earthquakes that occurred on March 27, 2021, in the Adriatic Sea, characterized by seventeen earthquakes greater than Ml 2, occurring in less than two hours with the main shock of magnitude Mw 5.2. In the pre-seismic phase, with a time window of five days from the first earthquake, three types of signals have been detected in temporal sequence, which occur with decreasing times from the seismic event. The start of the monitoring is given by the emission of radon gas Rn-222, followed by the emission of radio anomalies within the frequency band of 3 Hz, and then by the direction of electromagnetic signals describing the future epicentral zone. Applying this method, in this case, resulted in a successful prediction regarding the time window and epicentral zone but not the magnitude.