The effect of a compact ionosphere disturbance over the earthquake: A Focus on Schumann resonance

Abstract

We model perturbations of vertical electric and horizontal magnetic fields of Schumann resonance by a localized seismogenic non-uniformity in the Earth–ionosphere cavity with simultaneous accounting for the day–night non-uniformity. The source and receiver are placed at the same meridian and the latitudes covering 22.5° N and 22.5° S. The propagation path is positioned at the night (60° E) or the dayside (120° E) of morning terminator. The localized nonuniformity moves either along or across the propagation path. The full wave solution is used in the form of Riccati equation for finding the propagation parameters. The spectral components of fields are computed with the 2D (two dimensional) telegraph equations. Numerical estimates were obtained of the impact of the localized ionosphere non-uniformity on the electric and magnetic field amplitudes at a set of Schumann resonance frequencies for various positions of disturbances relative to the propagation path. It is shown that the impact of compact nonuniformity grows with increasing frequency. Field modifications are of interference nature. The day–night asymmetry provides a minor impact, and one may neglect this non-uniformity. The model was applied to interpret observations with a point source in Southeast Asia, Africa, or in South America. The observer was positioned at the Moshiri observatory, Japan. The earthquake focus modifying the conductivity of mesosphere was located at Taiwan. Perturbations of amplitude spectra of Schumann resonance were computed and their similarity to the observations was demonstrated.