There are a few ways to predict future volcanic activity. The first method, which is the most widely used, is to study the geographic area where the volcano resides. Usually, volcanoes may produce many small earthquakes preceeding a volcanic eruption, as Mount Saint Helens did in Washington in 1980. Vulcanologists are continually studying these and other effects, such as increases in the temperature of the volcano, to find ways of giving warning of an coming eruption.Although there seems to be little man can do to prevent an eruption, some attempts to lessen the damage caused by lava flows have been successful. Streams of lava have been diverted from a course which threatened to overwhelm a town by bombing the flow nearer the eruption vent and diverting the fluid lava into another area. Slowing part of a flow by building walls or by cooling the lava with streams of water may be possible in some cases.