It is not exactly an early warning system, but earthquakes may indeed hint at their intentions before they rumble. According to a large satellite survey, a few hours before a night-time earthquake there is a significant reduction in the intensity of very low frequency radio waves coming from beneath the ground in the region.
Frantisek Nemec of the University of OrlĂ©ans in France and colleagues put together two-and-a-half years of electromagnetic wave readings taken by the French satellite DEMETER. They analysed the intensity of these emissions for more than 9000 earthquakes with magnitudes 4.8 or greater, and compared them with…
