The use of subionospheric VLF/LF propagation for the study of lower ionospheric perturbations associated with earthquakes
- Advanced Wireless Communications Research Center and Research Station on Seismo Electromagnetics, University of Electro-Communications, 1-5-1 Chofugaoka, Chofu Tokyo 182-8585 (Japan)
It is recently recognized that the ionosphere is very sensitive to seismic effects, and the detection of ionospheric perturbations associated with earthquakes (EQs), attracts a lot of attention as a very promising candidate for short-term EQ prediction. In this review we propose a possible use of VLF/LF (very low frequency (3-30 kHz)/low frequency (30-300 kHz)) radio sounding of seismo-ionospheric perturbations. We first present the first convincing evidence on the presence of ionospheric perturbations for the disastrous Kobe EQ in 1995. The significant shift in terminator times in the VLF/LF diurnal variation, is successfully interpreted in terms of lowering of the lower ionosphere prior to the EQ, which is the confirmation of seismo-ionospheric perturbations. In order to avoid the overlapping with my own previous reviews [1, 2], we try to present the latest results including the statistical evidence on the correlation between the VLF/LF propagation anomalies (ionospheric perturbations) and EQs (especially with large magnitude and with shallow depth), a case study on the Indonesia Sumatra EQ (wavelike structures in the VLF/LF data), medium-distance (6{approx}8 Mm) propagation anomalies, the fluctuation spectra of subionospheric VLF/LF data (atmospheric gravity waves effect, the effect of Earth's tides etc.), and the mechanism of lithosphere - atmosphere - ionosphere coupling. Finally, we indicate the present situation of this kind of VLF/LF activities going on in different parts of the globe and we suggest the importance of international collaboration in this seismo-electromagnetics study.
- OSTI ID:
- 21428648
- Journal Information:
- AIP Conference Proceedings, Vol. 1286, Issue 1; Conference: 1. international conference on science with very low frequency radio waves: Theory and observations, Kolkata (India), 13-18 Mar 2010; Other Information: DOI: 10.1063/1.3512884; (c) 2010 American Institute of Physics; ISSN 0094-243X
- Country of Publication:
- United States
- Language:
- English
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