摘要
In the present work, disturbances of the half-transparency frequency fbEs of the ionospheric sporadic E-layer are investigated in connection with earthquakes. The fbEs-frequency is proportional to the square root of the maximum ionisation density of the sporadic E-layer. In this work, it is shown that in 2/3 of the cases, two days before a seismic shock with magnitude M > 5.5 and on the day of the shock, an increase of the fbEs-frequency is obtained at sunset hours at distances from the epicenter R km. In contrast, before sunrise, the fbEs-value decreases. The data analysed are obtained by the three vertical ionospheric sounding stations“Kokubunji”, “Yamagawa”, and “Wakkanai” during some tens of years.
In the present work, disturbances of the half-transparency frequency fbEs of the ionospheric sporadic E-layer are investigated in connection with earthquakes. The fbEs-frequency is proportional to the square root of the maximum ionisation density of the sporadic E-layer. In this work, it is shown that in 2/3 of the cases, two days before a seismic shock with magnitude M > 5.5 and on the day of the shock, an increase of the fbEs-frequency is obtained at sunset hours at distances from the epicenter R km. In contrast, before sunrise, the fbEs-value decreases. The data analysed are obtained by the three vertical ionospheric sounding stations“Kokubunji”, “Yamagawa”, and “Wakkanai” during some tens of years.
