Subionospheric VLF/LF Probing of Ionospheric Perturbations Associated with Earthquakes: A Possibility of Earthquake Prediction

Abstract

The VLF (Very Low Frequency) / LF (Low Frequency) receiving network has been established in Japan, which is composed of seven observing stations (Moshiri (Hokkaido), Chofu (Tokyo, UEC, University of Electro-Communications), Tateyama (Chiba), Shimizu (Shizuoka), Kasugai (Aichi), Maizuru (Kyoto) and Kochi (Kochi)), and three additional foreign stations have been established in Kamchatka, Taiwan and Indonesia. At each station we observe simultaneously several VLF/LF transmitter signals (two Japanese transmitters with call signals fo JJY (Fukushima), JJI (Miyazaki)), and foreign VLF transmitters (NWC (Western Australia, Australia), NPM (Hawaii, USA), NLK (Washington, USA)). This Japanese VLF/LF network is used to study the ionospheric perturbations associated with earthquakes, and we present two recent results; (1) a statistical result on the correlation between VLF/LF propagation anomalies and earthquakes, and (2) the latest results during the last six months on the two particular propagation paths; JJY-Moshiri and JJY-Taiwan. Then, we discuss the correlation of ionospheric perturbations with earthquakes in the sense of a possibility of earthquake prediction by means of VLF propagation anomalies.