GNGTS 2016 - Atti del 35° Convegno Nazionale

288 GNGTS 2016 S essione 2.1 any position on the earth going from north to south or vice versa. Being so, it is extremely important to verify whether the satellite passing into the sensitive region (Fidani, 2015) over the 12 hours in advance is recording anomalies in the ionosphere. The verification of this is equivalent to determining whether the abnormal ionospheric perturbations started to appear for almost a day before the strong earthquake. This observation has been made for other physical variables (Anagnostopoulos et al. , 2012); even if without a discussion in terms of statistical correlation. The fact that the satellite moved with a synchronous orbit to the Sun’s position, means that it passes over the earth’s surface always at the same local time every 12 hours. The observed correlation appeared only when the local time of the satellite was near dawn and dusk. If the local time over the 16 plus years of this investigation is draw, it was discovered that the satellite local time was not constant, see Fig. 3. After 2011, the local time of the satellite shifted away from the local time that allowed to obtain the positive correlation. Even solar activity is able to modulate the correlation as the active sun reduces days that are suitable for the calculation of the correlation. Therefore, during periods of high solar activity there will always be a few days when the geomagnetic activity is low enough to look for a correlation between the precipitation of electrons and strong earthquakes. These two modulations have different periods, 11 years for the Sun and around 20 years for the change in the local time, as well as different phases. From the combination of these it is plausible to forecast the periods when to search for a correlation. One of these periods is 5 years from today. Fig. 2 – The earthquake - electron burst correlation calculated over 144 hours, the second significant peak is above the threshold of 3 sigmas in yellow, the average is the red line. Fig. 3 – The local time of the NOAA-15 satellite during the more than 16 years of this study. The point density estimates the probability of detecting electron bursts which are probably not due to solar activity which is depicted in the center of this plot; strong earthquakes which were anticipated by electron bursts occurred 2-3 hours before, are indicated in red. References Anagnostopoulos, G.C., Vassiliadis, E., Pulinets, S.; 2012: Characteristics of flux-time profiles, 20 temporal evolution, and spatial distribution of radiation-belt electron precipitation bursts in the upper ionosphere before great and giant earthquakes. Ann. Geophys. – Italy 55, 21–36. Evans, D. S. and Greer, M. S.; 2004: Polar Orbiting Environmental Satellite Space Environment Monitor – 2: Instrument Descriptions and Archive Data Documentation, NOAA Technical Memorandum January, version 1.4, 155 pp.