GNGTS 2021 - Atti del 39° Convegno Nazionale

GNGTS 2021 S essione 2.1 196 has a certain degree of dependence from the first detected. Regarding the possible physical link able to cover more than 2,000 km between the Earth’s crust and the ionosphere throughout the atmosphere, magnetic pulses have been hypothesized to influence the high-energy charged particles’ motion (Galper et al., 1995). Thus electron bursts and magnetic pulses would be considered as dependent candidate precursors. Recent measurements of magnetic pulses on the occasions of strong earthquakes have contributed to suggesting an efficient process may influence the ionosphere (Fidani et al., 2020). In this latter work, the magnetic data analysis at the Chieti Station of the Central Italy Electromagnetic Network, performed through two independent sample systems of the same signal, showed that a large number of pulses were recorded in the ELF band below 10 Hz with B mostly in the range of 2.5 - 80 nT. Specifically, the model proposed for analyzing magnetic pulses consisted of diffused underground electrical currents throughout a conductive strip between the Apennines and the Adriatic Sea. The current required to induce detected pulses is greater than 40 kA for the strongest pulses. Moreover, two characteristics of these pulses are significant to the electron disturbances in the lower part of the inner Van Allen Belts: the frequency band and the diffuse current dimensions. In fact, the measured pulse frequency under 10 Hz is around the bouncing resonance of electrons with energies between 30 keV and 100 keV (Walt, 1994); exactly as measured onboard NOAA satellites. This means Fig. 3. The probability gain (3) due to the contribution of EB and MF detections. This gain is calculated with respect to the maximum event correlation between EB s and MF s on the abscissa, which comes from P(EB|MF) , and to the maximum event correlation between EQ s and EB ∩ MF s on the ordinate, which is derived from P(EQ|EB ∩ MF) . Δt* = T EB – T MF is thought to be the drifting time of electrons from the ionosphere above the epicenter to the cross with the NOAA satellite. Therefore, G EB ∪ MF is described by the contours if Δt between EB s and MF s correlation is shifted by Δt* , that is the dependence between EB s and MF s. The white dotted line on the left and the black one on the right represents G EB ∪ MF limits of validity.