Statistical relation between earthquakes and anomalous line-of-sight propagation in the VHF band and radio ducts

Abstract

In our previous paper, statistical relation between anomalous line-of-sight propagation in the VHF band and occurrences of earthquakes was presented. Basically, the anomalous propagation is mainly caused by anomalous refractive index of low atmosphere. In the present paper, the anomalies of the refractive index is captured by both the direct observation of radio ducts and the anomalous propagation in the VHF band, and the relation between them and the earthquakes are statistically clarified. Furthermore, the influences of meteorological conditions, which may disperse the anomalies of refractive index in the low atmosphere, are discussed. As a result, relation between anomalous propagation and earthquakes became increasingly clear by using anomalous propagation that concurrent with S-type ducts and meteorological conditions, wind velocity.