  In this paper we present results of a comparison between ultra low frequency
(ULF) electromagnetic (EM) radiation, recorded by an electric field instrument
(ICE) onboard the satellite DEMETER in the topside ionosphere, and the
seismicity of regions with high and lower seiismic activity. In particular we
evaluated the energy variations of the ULF Ez-electric field component during a
period of four years (2006-2009), in order to examine check the possible
relation of ULF EM radiation with seismogenic regions located in central
America, Indonesia, Eastern Mediterranean Basin and Greece. As a tool of
evaluating the ULF Ez energy variations we used Singular Spectrum Analysis
(SSA) techniques. The results of our analysis clearly show a significant
increase of the ULF EM energy emmited from regions of highest seismic activity
at the tectonic plates boundaries. We interpret these results as suggesting
that the highest ULF EM energy detected in the topside ionosphere is originated
from seismic processes within Earth's crust. We understand the results of the
present study as confirming previous evidence that the ULF EM anomalous wave
activity in the ionosphere can be considered a useful earthquake precursory
signal
