Use of satellites to detect seismo-electromagnetic effects

International audienceThe seismo-electromagnetic effects are the electric and magnetic perturbations caused by natural geophysical activity such as earthquakes and volcanic eruptions. They include: electromagnetic emissions in a large frequency range, perturbations of ionospheric layers, anomalies on the records of VLF transmitter signals, nightglow observations. The hypotheses concerning the electromagnetic wave emissions during earthquakes are: direct wave production by compression of rocks near the focal point, or electric discharges due to a redistribution of electric charges in the ground (piezoelectric or electrokinetic effects). Such phenomena are of great interest, because they start a few hours before the shock and can be considered as short-term precursors. However, not all earthquakes produce such perturbations. These phenomena were recorded at ground-based stations as well as on satellites. Ground campaigns, close to the epicenters, are a priori easier to manage, but on the other hand, satellite observations provide coverage over most of the active seismic zones of the Earth. Satellite observations are useful in places that usually have a low-level background noise. This paper presents in a first time a review of these phenomena, and of the various hypotheses put forward. The use of satellites for studying these events, and related problems are also discussed