Statistical Study on Variations of the Ionospheric Ion Density Observed by DEMETER and Related to Seismic Activities

Abstract

In this paper, we present the result of a statistical study performed on the ionospheric ion density variations above areas of seismic activity. The ion density was observed by the low altitude satellite DEMETER between 2004 and 2010. In the statistical analysis a superposed epoch method is used where the observed ionospheric ion density close to the epicenters both in space and in time is compared to background values recorded at the same location and in the same conditions. Data associated with aftershocks have been carefully removed from the database to prevent spurious effects on the statistics. It is shown that, during nighttime, anomalous ionospheric perturbations related to earthquakes with magnitudes larger than 5 are evidenced. At the time of these perturbations the background ion fluctuation departs from a normal distribution. They occur up to 200 km from the epicenters and mainly 5 days before the earthquakes. As expected, an ion density perturbation occurring just after the earthquakes and close to the epicenters is also evidenced.

Geosystemics View of Earthquakes

“…Ref. [ 105 ] confirmed and improved the previous results on the full lifetime of the DEMETER satellite. Their main result is that there is a significant positive or negative deviation of ion density around five days before the earthquake occurrence within 200 km of the future epicenter.…”

Nightside ULF Waves Observed in the Topside Ionosphere by the DEMETER Satellite

“…In contrast, fluctuations in the electron density shown in the bottom panel of Figure a do not have such a conjugate feature. Some research suggests that plasma density shows the seasonal variation in different hemispheres (e.g., Yan et al, ); we have checked the global distribution of electron density, which does show the seasonal variation in different hemispheres. The global distribution of δNe/Ne 0 does not show the identical effect with that of electron density, as δNe/Ne 0 reflects the higher‐frequency density variations, which is different from the original background electron density variations.…”

The Langmuir Probe Onboard CSES: data inversion analysis method and first results

“…From its records, many ionospheric plasma perturbations related to seismic events have been detected (Sarkar et al, , ; Zhang XM et al, , b; Liu J et al, ). Furthermore, statistical analysis of plasma parameters has been developed to ascertain the relationships between ionospheric perturbations and large earthquakes (He Y et al, , ; Parrot, ; Píša et al, ; Li M and Parrot, ; Yan R et al, ).…”