Subionospheric VLF/LF probing of ionospheric perturbations associated with earthquakes: A possibility of earthquake prediction

The VLF(Very Low Frequency) / LF(Low Frequency) receiving network is established in Japan, composed of seven observing stations (Moshiri (Hokkaido), Chofu (UEC, University of Electro-Communications), Tateyama (Chiba), Shimizu, Ka-sugai (Nagoya), Maizuru (Kyoto) and Kochi), and a few additional foreign stations are established in Kamchatka, Taiwan and Indonesia. At each station we observe simultaneously several VLF/LF transmitter signals (Japanese JJI (40 kHz, Fukushima), JJI (Ebino, Kyushu)), and foreign VLF transmitters (NWC (Australia), NPM (Hawaii), NLK (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 monthson the two particular propagation paths; JJY-Moshiri and JJY-Taiwan. Some discussions are done on the correlation of ionospheric perturbations with the earthquakes in the sense of a possibility of earthquake prediction by means of VLF propagation anomalies.