"Earth scientists have begun to forecast damaging earthquakes in California. Although quake forecasting is still maturing, it is now reliable enough to make official earthquake warnings possible. These warnings help government, industry, and private citizens prepare for large earthquakes and conduct rescue and recovery efforts in the aftermath of destructive shocks. In recent years, earthquake forecasting has advanced from a research frontier to an emerging science. This science is now being applied in quake-plagued California, where shocks are closely monitored and have been studied for many years."
U.S. Geological Survey: http://www.usgs.gov/