Вариации критической частоты слоя F2 во время землетрясения 16 сентября 2004 года на востоке Якутии

The article studies ionosphere variations during the earthquake that occurred in the eastern part of Yakutia on September 16, 2004 with a magnitude of Mb-4.3/3. Data received from the station of vertical zonding DPS-4 in Yakutsk has been analyzed. The results showed critical frequency of F-layer (foF2). Discretion of a frequency step is 0,05 Mh. Thus we can confidently count out meanings of critical frequencies of F-layer (foF2)from ionograms and make exact measures of ionospheric parameters under condition of diffuseness and ionospheric disturbances. According to analyses of ionospheric materials it is established that critical frequencies of the F2 layer increase 2-3 days before the earthquakes and decreases during the earthquake.