Dynamics of vertical ionospheric inhomogeneities over Irkutsk during 06:00-06:20UT 11/03/2011 caused by the Tohoku earthquake

TL;DR

This study investigates the vertical ionospheric irregularities caused by the Tohoku earthquake, revealing that acoustic shock waves from seismic activity can explain observed plasma disturbances within the first 20 minutes post-quake.

Contribution

It demonstrates that seismic-generated acoustic shock waves can account for early ionospheric irregularities, combining observational data with numerical simulations.

Findings

Vertical irregularities of 5-40 km range observed post-earthquake

Irregularities explained by acoustic shock wave propagation from seismic source

Limitations identified in current ionosonde resolution for detailed analysis

Abstract

According to the data of quasi-vertical sounding at Usolie-Tory path (midpoint - 52.3N, 103E, 120km distance), the dynamics of vertical structure of the midscale inhomogeneities of the plasma frequency was reconstructed. These irregularities are caused by Tohoku earthquake 11/03/2011 (38.3N, 142.4E). Observed horizontal velocities of propagation in the ionosphere and the spatial scales of the wave-like disturbance modes, generated by earthquakes, are calculated. As a result of numerical simulation involving the data from TALAYA seismic station (TLY, 51.7N, 103.7E) and comparison with the experiment it is shown that the vertical ionospheric irregularities of 5-40km range observed in first 20 minutes after the beginning of observations of effects (from 06:00 to 06:20 UT) are qualitatively explained by travelling of acoustic shock wave cone ( Mach cone ) from supersonic ground source - seismic wave to the heights up to 200km. It is shown that the most likely source of the shock wave were Z and E components of the seismic oscillations observed at TLY station. Irregularities observed after 06:20UT were apparently linked with other mechanisms. It is shown that the existing temporary CHIRP ionosonde temporal resolution (60 seconds) and the ionogram inversion technique used are not enough for detailed diagnosis of fine spatial vertical structures of this process.