GNGTS 2014 - Atti del 33° Convegno Nazionale

30 GNGTS 2014 S essione 2.1 same day; therefore, such days were excluded from the correlation. In past works (Fidani et al. , 2010) the Ap daily threshold was fixed at 18, while the three hour Ap indexes were considered with a threshold fixed at 13. Finally, due to long period Sun influences which had already been reported in Fidani works, annual and eleven year modulations of the thresholds associated with the two integer Ap indexes, were also applied to better exclude data with geomagnetic indexes. Several correlation peaks appeared from the first electron energy channels corresponding to 30 keV - 100 keV detected by the vertical telescope. Whereas, correlation peaks did not appear from other electron energy channels utilising vertical telescope or from any electron energy channels utilising horizontal or omnidirectional telescopes. Furthermore, no correlation peaks up until now have appeared from similar NOAA-15 proton analyses. The same algorithm was applied to the particle databases of all other polar NOAA satellites, but no correlation peaks were observed from the first electron energy channels, nor from any other energy channels or particle types. The dusk/noon orbit of NOAA-15 was the only one different from the other NOAA POES orbits, which were all characterised by day/night. Correlation plots of 30 keV - 100 keV energy channel electron bursts are shown in Fig. 2, depending on the earthquake epicentre projection altitudes. The plot ranges ±3 days in time difference between earthquakes and semi orbit electron bursts. The distribution shapes and average values calculated on ±3 days were compared with standard deviations of correlation events, evidencing super-poissonian distributions. Significant correlation peaks appeared between 2 and 3 hours of positive time difference, which means that the electron burst was observed before the corresponding earthquake. The peak started to be significant when considering earthquake projections above 1500 km altitudes. The correlation was maximised by using earthquake magnitude M ≥ 6 only. Pitch angle restrictions required that the particles be precipitating, meaning that their values were mostly in the loss cone. Specifically, particles in these electron bursts concentrated in intervals around 65° and 135°. Results in Fig. 2 were obtained neglecting pitch angles far from these values, with 30° ≤ α ≤ 80° and 120° ≤ α ≤ 160°. The earthquake depths lower than 200 km were considered, that is they had to be close to the surface. Correlation discussion. Epicentre locations whose earthquakes were correlated with electron bursts, were those in both the Indonesian and Philippine Regions, with few in South Fig. 1 – Cumulative daily number counting rates of electrons, exceeding the threshold xs, in the drift loss cone over 13 years of NOAA-15 detection; it was obtained in a low L-shell interval for electron energy from 30 keV to 100 keV of the zenith telescope.