Atmospheric electricity coupling between earthquake regions and the ionosphere

Abstract

a b s t r a c tWe propose a mechanism to explain suggested links between seismic activity and ionospheric changes detected overhead. Specifically, we explain changes in the natural extremely low-frequency (ELF) radio noise recently observed in the topside ionosphere aboard the DEMETER satellite at night, before major earthquakes. Our mechanism utilises increased electrical conductivity of surface layer air before a major earthquake, which reduces the surface-ionosphere electrical resistance. This increases the vertical fair weather current, and (to maintain continuity of electron flow) lowers the ionosphere. Magnitudes of crucial parameters are estimated and found to be consistent with observations. Natural variability in ionospheric and atmospheric electrical properties is evaluated, and may be overcome using a hybrid detection approach. Suggested experiments to investigate the mechanism involve measuring the cut-off frequency of ELF ''tweeks'', the amplitude and phase of very low frequency radio waves in the Earth-ionosphere waveguide, or medium frequency radar, incoherent scatter or rocket studies of the lower ionospheric electron density.

Brief Communication: Earthquake–cloud coupling through the global atmospheric electric circuit

“…Previously, Harrison et al (2010) argued that enhanced ionisation in the lower atmosphere (and, specifically, in the planetary boundary layer), will increase the vertical current flow always present in fair weather from the global atmospheric electric circuit (e.g. Rycroft et al, 2012).…”

“…The full methodology was discussed in the description of the ALICE mechanism given in Harrison et al (2010). For an ionospheric potential V I , which is assumed to be an equipotential region since the ionosphere's conductivity is many orders of magnitude greater than that of the air's conductivity below it, the conduction current density J c is given by…”

A Review of Low Frequency Electromagnetic Wave Phenomena Related to Tropospheric-Ionospheric Coupling Mechanisms

“…Harrison et al (2010) suggest using tweeks to investigate possible ionospheric disturbances related to seismic activity. Specifically, they propose a mechanism to link seismic activity and changes in the local lower ionosphere that could be tested by measuring the tweeks cutoff frequency.…”

Is there any difference in local time variation in ionospheric F2-layer disturbances between earthquake-induced and Q-disturbance events?

“…In contrast, Omori et al (2007) argued that the radon emanation increased the number density of small ions and the atmospheric conductivity, consequently decreasing the atmospheric electric field, a view also shared by Harrison et al (2010).…”