GEOPHYSICAL RESEARCH, 2019, vol. 20, no. 1, pp. 27-37.

UDC 550.34, 551.510.535, 537.87

Abstract  References   Full text (in Russian)


M.S. Solovieva(1), A.A. Rozhnoi(1), A.K. Rybin(2)

(1) Schmidt Institute of Physics of the Earth, Russian Academy of Sciences, Moscow, Russia

(2) Research Station RAS, Bishkek, Kyrgyzstan

Abstract. The very low-frequency and low-frequency (VLF/LF) observations of electromagnetic signals at the receiving stations KGZ in Bishkek (Kyrgyzstan) and VAR (Varanasi, India) has been used for the multiple-factor analysis in connection with two strong earthquakes in Nepal that occurred on April, 25th (Mw7.8) and on May, 12th (Mw7.3), 2015. Signal variations were considered from VTX (17.0 kHz, India), NWC (19.8 kHz, Australia), and JJY (40 kHz, Japan) transmitters. Two crossing wave paths, NWC–KGZ and JJY–VAR that passed over the earthquake epicenters, have shown abnormal behavior of signals during several days before the first, stronger earthquake. Anomalies were also observed for two other wave paths from the VTX transmitter that were completely inside the area of possible earthquake precursors. Having considered other factors that could influence characteristics of VLF/LF signals (magnetic storms, proton flashes, relativistic electro’s fluxes, change in atmospheric pressure, typhoons) we can conclude that the anomalies observed in signals are most probably caused by the processes of earthquake preparation.

Keywords: earthquakes, sub-ionospheric electromagnetic signals, the lower ionosphere.


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