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.
Radon gas can escape through the newly formed cracks, and electrical resitivity decreases.
The newly forming cracks and increasing stress may also result in a tiny increase in local seismicity. Stage III Groundwater from surrounding areas can now flow into the new cracks. Because the cracks are now filled again, the P-wave velocity can increase back to normal. The ground's uplifing also ceases and radon gas emission decreases. Electrical resistivity is still decreasing.