I can believe it. The Earth is a big electromagnetic machine, as are all the planets and the Sun. Squeeze a tectonic plate against another, and the effect is like a piece of quartz generating electricity, and electromagnetic emissions may affect natural electromagnetism in play in and around the Earth. Whether mankind can identify changes in signals and match them to probable earthquakes is another thing. In any event, warnings would probably be too late and of little effect.
There was a 7+ earthquake here three years ago. I heard it before I felt it.