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Based on our recently developed numerical simulation technique, we simulated the electrokinetically induced co-seismic electromagnetic signals associated with seismic waves. We focused on the characteristics of the co-seismic electromagnetic signals generated by a double couple point source or a finite fault source in the models with different structures. The effects of source time function type and...
The depression (reduction in amplitude) of ULF (ultra-low-frequency) magnetic field variations observed on the Earth's surface is found for the recent huge Japan earthquake (EQ) (magnitude(M) ∼ 9.0) on March 11, 2011 which is a typical oceanic EQ of the plate type. In order to confirm the presence of such a ULF depression, we have also studied the additional two huge oceanic EQs in the Kurile islands...
In order to verify and clarify the ULF seismo-magnetic phenomena, a statistical investigation of the relation between magnetic anomalies and local seismicity has been performed. Geomagnetic data observed during 2001∼2010 at the Kakioka observation (JMA), Izu and Boso stations have been analyzed. Energy of ULF geomagnetic signals at the frequency around 0.01Hz has been investigated by wavelet transform...
This paper was intended to find out any relation between anomalous line-of-sight propagation on VHF radio band and occurrences of earthquakes near the radio propagation path. For that purpose, we established a multidirectional VHF band monitoring system and monitored the waves continuously over the long time. After stochastic consideration of fluctuation in the monitored waves, it was found out that...
We propose an satellite observation to investigate preseismic lithosphere-atmosphere-ionosphere (LAI) coupling. Preliminary mission analysis shows that it is possible to prove not only a statistical correlation but also causation between earthquake and ionospheric anomaly even by three dedicated nano-satellites. The observation of proposed satellite constellation promotes a comprehensive understanding...
The ionospheric perturbations have been found to take place prior to an earthquake (EQ) (with magnitude greater than 5.5 (or so) and with shallow depth), on the basis of the long-term VLF/LF subionospheric propagation. Then, there have been presented the precursors to the recent 2011 Japan EQ. That is, the ionospheric perturbation was definitely found on the basis of two completely different phenomena...
In ELF range, we finally detected electromagnetic (EM) pluses directly excited by earthquakes in a deep borehole. By simultaneous capturing of waveforms of magnetic component of the EM pulses and of seismic waves measured at the EM observation site, we have confirmed that seismic P-wave readily excited EM waves. The result suggests that EM waves were very sensitive to the vibrations of seismic waves...
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