Predicting earthquakes is supposed to be impossible, although there are a few of us who think that things like earthquake storms and stress analysis of faults will give us one way to do it. Bt there are other was that are being studied as well one of which is looking for the precursors of a quake. When you put a material under stress things happen to it, there may be noise or electricity generated as well as other things.
One of the things being studied is ozone produced by the stress on the rocks causing electrical discharge and ionizing the oxygen in the air then creating ozone. A paper was just released today in the journal Applied Physics Letters, postulating this and suggesting that this may be why animals seem to react before a quake happens.
- What is the difference between the predictability and frequency of hurricanes and earthquakes (wiki.answers.com)