TITLE:
Variations of Atmospheric ELF/VLF Radio Noise Due to Seismogenic Modifications in Tropospheric Conductivity
AUTHORS:
Masashi Hayakawa, Alexander P. Nickolaenko
KEYWORDS:
ELF/VLF Radio Noise, Earthquake Precursor, Pre-Seismic Modification, Conductivity Anomaly in the Lower Atmosphere, Radioactive Radon Gases, CG Lightning Discharges, IC Discharges, Cloud-to-Ionosphere Discharge
JOURNAL NAME:
Open Journal of Earthquake Research,
Vol.13 No.2,
May
27,
2024
ABSTRACT: We suggest a possible explanation of the influence of pre-seismic activity on the registration rate of natural ELF(extremely low frequency)/VLF(very low frequency) pulses and the changes of their characteristics. The main idea is as follows. The distribution of the electric field around a thundercloud depends on the conductivity profile of the atmosphere. Quasi-static electric fields of a thundercloud decrease in those tropospheric regions where an increase of air conductivity is generated by pre-seismic activities due to emanation of radioactive gas and water into the lower atmosphere. The electric field becomes reduced in the lower troposphere, and the probability decreases of the cloud-to-ground (CG) strokes in such “contaminated” areas. Simultaneously, the electric field grows inside and above the thunderclouds, and hence, we anticipate a growth in the number of horizontal and tilted inter-cloud (or intra-cloud) (both termed as IC discharges) strokes. Spatial orientation of lightning strokes reduces vertical projection of their individual amplitudes, while the rate (median number strokes per a unit time) of discharges grows. We demonstrate that channel tilt of strokes modifies the spectral content of ELF/VLF radio noise and changes the rate of detected pulses during the earthquake preparation phase.