A network of reception of over-horizon VHF signals associated with earthquakes and some preliminary results

The reception of over-horizon VHF signal is recently found to be useful for the study of seismo- atmospheric perturbation. So, we have extended our present single path from Chofu to FM Sendai to a nation-wide network. This paper describes our newly established network for reception of over-horizon VHF signals. First, in order to have a triangulation to locate the seismo-atmospheric perturbation for the FM Sendai, we have installed one more station in Kanazawa, to be coordinated with our pre-existing station at Chofu. Other paths are (1) FM Shizuoka to Wakayama and (2) Osaka station to Kagoshima. This VHF system is reported, together with some preliminary results for a recent rather big earthquake (2004 Off Kii-peninsula earthquakes).