Volcanoes have been called the thermostat of the planet. They wreak havoc, but also spawn far-ranging benefits for soil and air. Some earth scientists now say that the vast swath of destruction from a volcanic eruption can be a source of creation.

Most land volcanoes erupt along plate edges where ocean floors plunge deep under continents and melting rock rises to the surface as magma. The earth's fragmented crust pulls apart and the edges grind past or slide beneath each other at a speed of up to 8 in (20 cm) per year. But just as our blood carries nutrients that feed our body parts, volcanoes do the same for the skin of the earth.

Magma contains elements required for plant growth, such as phosphorus, potassium, magnesium and sulfur. When this volcanic material is blasted out as ash, the fertilization process that moves the nutrients into the soil can occur...