On the Geomagnetic Field Line Resonance Eigenfrequency Variations during Seismic Event

• Published in: Remote sensing (Basel, Switzerland) Switzerland), 2021-07, Vol.13 (14), p.2839
• Main Authors: Piersanti, Mirko, Burger, William Jerome, Carbone, Vincenzo, Battiston, Roberto, Iuppa, Roberto, Ubertini, Pietro
• Format: Article
• Language: English
• Subjects: acoustic gravity waves; coseismic effects; Coupling; earthquake; Earthquakes; field line resonance; Geomagnetic field; Gravity waves; Ionosphere; Lithosphere; lithosphere-magnetosphere coupling; Magnetic fields; Magnetometers; Magnetospheres; Observatories; Plasma density; Remote sensing; Resonance; Resonant frequencies; Satellites; Seismic activity
• ISSN: 2072-4292; 2072-4292
• DOI: 10.3390/rs13142839

In this paper, we report high statistical evidence for a seismo–ionosphere effects occurring in conjunction with an earthquake. This finding supports a lithosphere-magnetosphere coupling mechanism producing a plasma density variation along the magnetic field lines, mechanically produced by atmospheric acoustic gravity waves (AGWs) impinging the ionosphere. We have analysed a large sample of earthquakes (EQ) using ground magnetometers data: in 28 of 42 analysed case events, we detect a temporary stepwise decrease (Δf) of the magnetospheric field line resonance (FLR) eigenfrequency (f*). Δf decreases of ∼5–25 mHz during ∼20–35 min following the time of the EQ. We present an analytical model for f*, able to reproduce the behaviour observed during the EQ. Our work is in agreement with recent results confirming co-seismic direct coupling between lithosphere, ionosphere and magnetosphere opening the way to new remote sensing methods, from space/ground, of the earth seismic activity.