The main function of the U.S. Geological Survey's Hawaiian Volcano Observatory is to reduce the risk from volcanic activity.
People commonly think in terms of hazards reduction when they actually mean risk reduction.
Hazards are the natural events that can occur in a given area and the likelihood that they will occur in a given time period. Risk is a measure of the financial and human costs associated with the occurrence of such events. Nothing that we, as a society, can presently do will reduce hazards, but we can reduce risk by proper risk management. Risk management is something we each do all the time on a personal level. For example, insurance of various types are ways we reduce our risk of financial setbacks.