This could be a very helpful clue to forecasting earthquakes. In terms of prediction research, the most effort has been put into studying variation in seismicity rate. But, all of the studying has not produced a definate answer. Seismologists study the pattern of aftershocks and foreshocks. In Italy, China, and California, earthquakes have been successfully predicted using a noticed increase in background seismic activity.
Tiny shocks increase in number and magnitude leading up to a large shock.
If these foreshocks can be recognized as such in enough time to warn people in the necessary areas, many lives can be saved. No uplift, radon increase, etc. Stage II Cracks begin to develop in crustal rocks in the pre-quake area. The buildup begins to be visible as an uplift of the area. The cracked rocks do not propogate P-waves as easily and their velocity slows in the area.