I have asked this question many times around about, but i thought i'd ask you. I have a pet theory that the earth produces flare activity much like the sun, but less energetically. I figure these flares can be visible at times, as a "cold" plasma see: http://www.ipp.mpg.de/ippcms/eng/presse/pi/05_06_pi.html
It produces discharges in the sky(earths version of a CME) interperatated as ball lightning. And can also produce earth tremmers/quakes, like solar flares produce sunquakes. Hense the emission of "earth lights" prior to some quakes. I wondered if i could ask your oppinion, with your usual 10 in politeness?
As noted in my earlier (abortive) attempt to reply, this is outside my area of expertise, but I don't see why what you suggest wouldn't be possible. The Earth's electromagnetic field does contain a large amount of energy, and thanks to plasma captured from the solar wind, is capable of producing various kinds of electrical discharges at great altitudes -- and thanks to the energy produced by thunderstorms, even more energetic discharges (e.g., lightning) at lower altitudes. However, I'm not sufficiently familiar with the details of this subject to provide a definitive comment on your question about electromagnetic discharges.
However, I do feel certain that such effects cannot cause earthquakes. Since the Sun is a plasma, and its electromagnetic field is as much as ten thousand times stronger than ours, its surface can be roiled by its electromagnetic effects; but the solid body of the Earth cannot be significantly affected by the much weaker fields which exist here. There may well be minor electromagnetic discharges produced by major earthquakes, but the reverse just isn't credible.
Courtney Seligman Professor of Astronomy Long Beach City College