One possible explanation for earthquake occurrences from anomalous line-of-sight propagations in the very high frequency band by fast Fourier transform spectral analysis

TL;DR

This study suggests a potential link between earthquake occurrences and anomalous VHF band propagations, revealing that these signals share common spectral features and are possibly influenced by atmospheric gravity waves, indicating a lithosphere-ionosphere coupling.

Contribution

The paper introduces a spectral analysis approach to connect anomalous VHF propagations with earthquakes, highlighting a consistent frequency pattern and the role of atmospheric gravity waves.

Findings

Most anomalous signals share similar frequency peaks below 0.5Hz.

Spectral maxima are below the Brunt-Vaisala frequency, indicating gravity wave influence.

Potential evidence of lithosphere-ionosphere coupling related to earthquakes.

Abstract

This paper illustrated the possible relationship between the occurrences of the earthquake and the anomalous line-of-sight propagations in the very high frequency band by the fast Fourier transform spectral analysis. Despite many anomalous propagations appear in the different very high frequency band during the earthquake occurrences, the majority of these abnormal signals contain similar frequency distributions in the frequency domain. For the 31 anomalous propagation spectral distributions, 30 of them present the same curve peaks, within a frequency range of (0-0.5)Hz. Furthermore, for the first time, we found that the spectral maximum of all anomalous propagations are below the characteristic Brunt-Vaisala frequency (period T larger than 6 min), which happens to be the frequency range of the internal gravity waves, which might evidence that the atmospheric gravity waves should be responsible for the indirect coupling between lithosphere and ionosphere. These novel results might provide direct evidence to the relationship between the anomalous propagations in the very high frequency band and the occurrences of earthquakes.