An evidence on the lithosphere-ionosphere coupling in terms of atmospheric gravity waves on the basis of a combined analysis of surface pressure, ionospheric perturbations and ground-based ULF variations

Abstract

One major candidate of lithosphere-atmosphere-ionosphere (LAI) coupling mechanism is through atmospheric oscillations triggered near Earth's surface due to some pre-earthquake (EQ) effect, and this channel has been extensively proved by using meteorological disturbances much more easily treated than pre-EQ effects (Korepanov et al., 2009). In the present paper this channel is challengingly studied, for the first time, for pre-EQ phenomena, and we take a rather strong EQ named Niigata-chuetsu EQ on 23 October, 2004 (with magnitude of 6.8 and with depth of 13 km) for which we already know that the ionospheric perturbation did take place prior to the EQ . In this paper the LAI coupling has been intensively studied by means of coordinated observational data (surface atmospheric pressure data as an indicator of atmospheric gravity waves (AGWs), our own subionospheric VLF/LF data as a measure of ionospheric perturbations and the ground-based ULF data as a measure to monitor the modulation in the ionospheric dynamic region). The wavelet analyses for these parameters in different spatial regions have all indicated the enhancements of fluctuations in the wave frequency of 10 ~ 100 min (in the frequency range of AGWs). The correlation of wavelet spectra between the atmospheric pressure and VLF/LF amplitude has yielded a high value with the delay of a few hours, while there is nearly no distinct delay of the wavelet spectra between the ionospheric perturbation and the ground-based ULF fluctuation. These observational facts are compared with the theoretical estimation of AGW hypothesis, which may provide a convincing support to the AGW channel of the LAI coupling.

Magnetospheric–Ionospheric–Lithospheric Coupling Model. 1: Observations during the 5 August 2018 Bayan Earthquake

“…The authors in Korepanov et al [18], investigating surface atmospheric pressure and magnetic field data during meteorological events, concluded that AGWs are a possible candidate for seismo-ionospheric coupling. A similar study by Nakamura et al [19] for the 2004 Niigata-Chuetsu EQ (M6.8), using wavelet analyses, confirmed that enhanced variations in the period of 10-100 min of the surface atmospheric pressure and magnetic field data (which are in the range of AGW) enhanced the lower ionosphere perturbation. The authors in Endo et al [20], using the Japanese F-net wide-band seismic network data, found that, before the 2007 Niigata-Chuetsu Oki and 2008 Iwate-Miyagi EQs, the ground motions in the AGW ranges were enhanced when the lower ionosphere was perturbed.…”

Pre-Seismic Irregularities during the 2020 Samos (Greece) Earthquake (M = 6.9) as Investigated from Multi-Parameter Approach by Ground and Space-Based Techniques

“…Zhang et al [70] and Yang et al [71] used a Sounding of the Atmosphere utilizing Broadband Emission Radiometry (SABER) instrument installed on the Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) satellite temperature profile to examine E p related to AGW. Nakamura et al [72] have played out a similar assessment and endeavored to find the relating seismogenic sway for certain EQs. For the 2004 Niigata-Chuetsu EQ (M = 6.8), wavelet examination of those limits showed changes periods of 10 to 100 min which is in the extent of AGW.…”

Gravity Wave Activity in the Stratosphere before the 2011 Tohoku Earthquake as the Mechanism of Lithosphere-atmosphere-ionosphere Coupling

“…and AGW (10–100 min.) components in the ground motions [ 34 ], short-term crustal movements [ 35 ] (which also accompany the generation of seismic electric signals [ 36 , 37 ]), the fluctuations in the AGW range in surface atmospheric pressure as well as ULF magnetic field [ 38 , 39 ], and anomalies in the mesospheric ozone density [ 40 ]. These papers provide certain evidence to the AGW hypothesis in the LAIC process.…”