As with many natural hazards the only totally effective way of reducing or preventing the hazard is to remove all human presence from the area in which the hazard may occur. Of course with volcanoes this is not viable and very unlikely to happen due to the advantages of living on the rich agricultural soils of the volcano. This means that a volcano hazard is very difficult to prevent as it is impossible to prevent an actual eruption. The best way of reducing the danger of the hazard is to monitor volcanoes to give warning time for evacuation, and there are increasing efforts to encourage the local population in seismically active areas to become more involved with disaster preparedness to prevent catastrophe. Hazard Prediction Major volcanic eruptions do not happen spontaneously.
Some volcanoes show quite consistent patterns of activity while others are much more erratic.
Eruptions are preceded by various environmental changes which accompany the rise of magma toward the surface. The best way to predict eruptions is the monitoring of these changes. This is common near volcanoes as these too occur at tectonic plate boundaries. It is not fully understood whether volcanoes cause earthquakes or vice versa. This is sometimes a reliable factor to predict eruptions by as magma moving up through the volcano can cause the surface shape to change.