Volcanoes inspire awe with spectacular eruptions and incandescent rivers of lava, but often their deadliest hazard is what quietly falls from the sky.
When a large volcano erupts, as Mount Spurr appears close to doing about 80 miles from Anchorage, Alaska, it can release enormous volumes of ash. Fine ash can infiltrate the lungs of people and animals who breathe it in, poison crops and disrupt aquatic life. Thick deposits of ash can collapse roofs, cripple utilities and disrupt transport networks.
