Physics of auroral phenomena : proceedings of the 36th Annual seminar, Apatity, 26 February – 01 March, 2013 / [ed. board: A. G. Yahnin, A. A. Mochalov]. - Апатиты : Издательство Кольского научного центра РАН, 2013. - 215 с. : ил., табл.

О.M. Barkhatova andN. V. Kosolapova the layers F2, E and Es critical frequencies were cleared from the daily variation. The detection of simultaneous plasma and magnetic disturbances caused by MGW propagation is performed on the base of spectral characteristics comparison for cleared data of critical frequencies and geomagnetic field in the range of 10 -^-10 Hz. The comparison was carried out for the intensity maxima of corresponding spectra. Table 1 Earthquake date Epicenter coordinates Time of earthquake beginning, UT Magnitude Ionospheric stations Magnetic stations 17.07.2006 9.33° S, 107.26° E 08:19 7.7 Learmonth (21.9° S, 114° E) Learmonth (21.9° S, 114° E) 08.01.2006 36.30° N, 23.36° E 01:35 6 .8 San Vito (40,6 N, 17,8 E) Laquila (42.4 N, 13.3 E) MGW detection on experimental data The MGW detection is associated with the search for similar dynamic spectra features corresponding to simultaneously observed disturbances of ionospheric layers Es, E and F2 density and disturbances of X, Y, Z geomagnetic field components. At three days before the earthquake the number o f concurrences in considered spectral peaks is not more than one. This may indicate a low level of magnetogravitational activity in this period. A similar situation is noted at three days after the earthquake. However at two days before the earthquake and two days after them a number of observed simultaneous disturbances markedly increased - there is up to five concurrences during the day. Fig. 1 (left column) shows the dynamic spectra of ionospheric and magnetic parameters at two days before the earthquake (15 July). The arrows indicate the simultaneous spectral peaks o f critical frequencies and geomagnetic field disturbances. At the day of the considered earthquakes simultaneous plasma and magnetic disturbances are absent what indicate a weakening of magnetogravitational activity. 15 July 2006 17 July 2006 Spectrogramm T0F2 Spectrogramm V Spectrogramm Z | | Fig. 1 Dynamic spectra at two days before the earthquake (July, 15) and at day o f earthquake (July, 17). The three upper panels correspond to the dynamic spectra of critical frequencies layers F2, E and Es, the bottom three panels - the dynamic spectra of geomagnetic field X, Y, Z components. The horizontal axis represents time (UT), the vertical axis - the characteristic frequencies of plasma and magnetic disturbances. Arrows indicate the cases of MGW propagation. Vertical line indicates the start time o f earthquake 140