Sensitivity of ionosonde detection of atmospheric disturbances induced by seismic Rayleigh waves at different latitudes

Takashi Maruyama,Hiroyuki Shinagawa,Adel Akchurin,Kamil Yusupov

doi:10.1186/s40623-017-0600-z

Abstract

Ionospheric disturbance was observed in ionograms at Kazan, Russia (55.85^circ hbox {N}, 48.81^circ hbox {E}), associated with the M8.8 Chile earthquake in 2010 (35.91^circ hbox {S}, 72.73^circ hbox {W}). The disturbance was caused by infrasound waves that were launched by seismic Rayleigh waves propagating over 15,000 km along Earth’s surface from the epicenter. This distance was extremely large compared with the detection limit of similar ionospheric disturbances that were previously studied at lower latitudes over Japan. The observations suggest that the sensitivity of ionograms to coseismic atmospheric disturbances in the infrasound range differs at different locations on the globe. A notable difference in the geophysical condition between the Russian and Japanese ionosonde sites is the magnetic inclination (dip angle), which affects the ionosphere–atmosphere dynamical coupling and radio propagation of vertical incidence ionosonde sounding. Numerical simulations of atmospheric–ionospheric perturbation were conducted, and ionograms were synthesized from the disturbed electron density profiles for different magnetic dip angles. The results showed that ionosonde sounding at Kazan was sensitive to the atmospheric disturbances induced by seismic Rayleigh waves compared with that at Japanese sites by a factor of sim3.Graphical

Highlights

Large earthquakes are known to cause appreciable ionospheric disturbances through lithosphere–atmosphere– ionosphere coupling
The resulting ionospheric perturbation is detected by various radio techniques
Neutral–ion coupling The magnetic inclination effect on the wave-induced electron density perturbation was estimated by examining the ion continuity equation under the influence of the neutral particle motion of acoustic waves that propagate upward, as described below (Maruyama and Shinagawa 2014), 11 March 2011 Tohoku-oki (M7.7 Aftershok)

Summary

Introduction

Large earthquakes are known to cause appreciable ionospheric disturbances through lithosphere–atmosphere– ionosphere coupling. The neutral particle motion of the acoustic waves induces alternating enhancements and depletions of plasma density through the neutral–ion collisions at ionospheric heights (Maruyama and Shinagawa 2014).

Results

Conclusion