Physics of auroral phenomena : proceedings of the 33rd Annual seminar, Apatity, 02 - 05 March, 2010 / [ed.: A.G. Yahnin, A. A. Mochalov]. - Апатиты : Издательство Кольского научного центра РАН, 2011. - 206 с. : ил.

“P hysics o f Auroral Phenom ena", Proc. XXXIII A n nu al Seminar, Apatity, pp. 1 4 7 -1 5 0 , 2011 © Kola Science Centre, Russian Academy of Science, 2011 Polar Geophysical Institute WAVE DISTURBANCES IN THE LOWER IONOSPHERE DURING THE EARTHQUAKES ON AUGUST 2006 N.G. Sergeeva, O.F. Ogloblina (Polar Geophysical Institute, Murmansk, Russia) Abstract. The experimental data, measured by a partial reflections radar in the Kola Peninsula at observatory Tumanny (69.0°N, 35.7°E) and vertical sounding of the ionosphere at observatory Sodankyla (67.37° N, 26.63° E) were analyzed with the purpose o f the reason finding out ionospheric responses to earthquakes on August 2006. The strong earthquakes were fixed by seismic stations, located in the Kola Peninsula and Scandinavia. Earlier, we have chosen ten the strong earthquakes, which took place under quiet geomagnetic field and at small (background) solar flares. In this study we have considered earthquakes which have occurred under other geophysical conditions in the Pacific and Indian Oceans. 1. Introduction Earthquakes influence on the ionosphere has been investigated more than 50 years with aim to find precursors of the earthquakes on ionosphere parameters. The forecasts of the strong earthquakes are necessary at present. The ionosphere represents the dynamic environment influenced by different disturbances. Mainly they come from the Sun, but some of them come from the lithosphere of the Earth. Earlier, we have considered in detail ten strong earthquakes, which took place at the western seaside of the Indonesia, near island Java, in region of island Sumatra, at Island of the king Eduard in Atlantic Ocean and at New Zealand. Under the quiet geomagnetic field and at small solar flares the reaction o f the high- latitude ionosphere to these strong earthquakes was seen basically in parameters of the lower ionosphere (Sergeeva N.G et a l, 2007; 2008; 2009 a; 2009 c). We have also analyzed spectra of the ordinary component amplitude o f the partial-reflected signal under the quiet geomagnetic field and at small solar flares on the days, when there were no strong earthquakes. In spectra of the ordinary component amplitude of partial-reflected signal only tidal atmospheric waves with the different periods were observed. It is proof that at days of the earthquakes the discovered internal gravity waves with the periods of some hours are connected with earthquakes (Sergeeva et a l, 2009b). The purpose o f this work is a finding of the general regularities in changes parameters of seismo-ionospheric disturbances in high-latitude ionosphere, caused by strong earthquakes on August 7 and 11, 2006. The earthquake on August 7 took place under very disturbed geomagnetic field and at weak solar flares of A- class. Another earthquake on August 11 took place under the quiet geomagnetic field and at several solar flares of B- class and C- class. 2. The analysis of experimental data The considered day on August 7 was strongly disturbed (£Kp =32.3). Index of disturbance Kp= 5.7 existed at 9-12 UT, that is classified as magnetic storm (Kp > 5). At the following days the geomagnetic activity decreased and on August 8 was already weakly. In figure 1 the magnetograms of the X- component of the geomagnetic field, measured at magnetic stations Soroya (70.54°N, 22.22°E) and Pello (66.90°N, 24.08°E) are submitted. 11 August 2006 Fig. 1. Magnetograms o f the X- component of the geomagnetic field on August 7 and 11, 2006 at stations Soroya (SOR) and Pello (PEL), (T -tim e o f the earthquakes beginning). First earthquake on August 11 took place under small positive bay of the geomagnetic field (125 nT). The weak solar flares o f А-class on August 7 were observed (fig.2 from the left). The solar activity increased gradually. In the following days on August 8 and 9 the solar flares of B- class began to appear. Solar flares of В-class and C-class were observed during on August 11 (fig.2 to the right). For August 7- 9 the variations of the particles of solar wind (the protons with energy > 1 MeV and electrons with energy > 2 MeV) were registered by satellites GOES-IO and 147 7 August 2006