How do people plan for volcanos and prevent or minimize damage?

Answer 1

Evacuation is the main thing governments can do to reduce loss of life. But for the most part there is no effective way stop the eruption/volcanic activity from happening, as the forces are too large to be countered.

Damage can be reduced by avoiding the known paths of lava from preceding eruptions, or by locating towns on the far side of an intervening hill or deep water body. The latter does, however, present a tsunami risk and does not protect from ashfall or pyroclastic events.