Plasma density variations observed on a satellite possibly related to seismicity Original Research Article

We discovered a reliable correlation between global distribution of seismic activity and ion density variations in the ionosphere on the basis of the analysis of a rather large data base of plasma density, which was recorded on board a Russian satellite Intercosmos 24 (more than 3000 orbits over the world). The best parameters to find a significant correlation between the two, are normalized standard deviation (NSD) and relative normalized standard deviation (RNSD). Maximal values of density NSD correlated with seismic activity are 10–20%. However, a clear correlation is found only for daytime (10–16 LT), quiet magnetic conditions and altitude range 500–700 km, while it disappears in nighttime and during magnetic storms. A mechanism of seismo-ionosphere coupling might be connected with slow gravity waves.