Defense structures are built to protect certain areas, while control structures are built to lessen snow accumulation and prevent the formation of cornices. The terrain and type of avalanche common to the area will determine which type of structure is best suited to eliminate or control the hazard. Areas of high snow accumulation or steep slopes use control structures to eliminate the avalanche initiation. Areas with shallow slopes or less snow accumulation use defense structures that divert the movement of the avalanche downslope from it's origin.