GNGTS 2018 - 37° Convegno Nazionale

344 GNGTS 2018 S essione 2.1 Given that the loop have the axis oriented approximately N-S, the idealised current flowing parallel to the ground plane able to induce in the loop will have approximately an E-Wdirection, which is perpendicular to the faults strike of Central Italy. However, this configuration required currents of at least 1.7 MA for the Norcia earthquake, which the E-W line is about 90 km away from Chieti, and 1.1 MA for the Capitignano earthquakes, which the E-W line is about 60 km away from Chieti, to produce the magnetic induction recorded from the loop at Chieti. These extremely high current values are difficult to justify and constitute a challenge to found other models of electric currents in the earth’s crust. Using the simple idealized model of an infinitesimally short, horizontal dipole (Bortnik et al., 2010) located at a depth d in the half-space z > 0, results are still more difficult to justify, Figure 3 middle model. Thus, a distributed electric current model was hypothesized where the concatenated flux to the loop was calculated with special functions, and gave a more acceptable electric current intensity and configuration, see Figure 3 right. Acknowledgements. Authors would like to thank Tommasi Cecci for realising the loops for the Avigliano Umbro and Norcia Stations. Additionally, Authors would like to express his thanks to Marco Eleuteri for realising the Narni Station loop. Authors would like to thank Adriano Nardi and Ernesto Tiberi for their contribution to installing the Norcia Station. Finally, Authors would like to thanks iccardo Rossi for the loop installed in the Perugia Station. References Bortnik J., Bleier T.E., Dunson C., and Freund F.; 2010: Estimating the seismotelluric current required for observable electromagnetic ground signals, Ann. Geophys., 28, 1615-1624. Fidani C. and Marcelli D.; 2017: Ten Years of the Central Italy Electromagnetic Network (CIEN) Continuous Monitoring, Open Journal of Earthquake Research, 6, 73-88. Fidani C.; 2017: Electricity perturbations observed around the October 30, 2016 Norcia earthquake, M = 6.5, 36 th GNGTS, Trieste. 314-316, Nov. 14-16. Landau L.D. And Lifsits E.M.; 1986: Fisica Teoricaa, Elettrodinamica dei mezzi continui, Editori Riuniti Edizioni Mir, Roma, p. 172. Orsini M. and Fidani C.; 2017: Magnetic perturbations observed around the October 30, 2016, Norcia, 36 th GNGTS, Novembrer 14 – 16, 2017, Trieste, 316-318. Fig. 3 - Three ground electric current models, infinite line on the left, infinitesimal dipole on the middle and distributed line currents.