A volcano is a mountain that opens downward to a pool of molten rock below the surface of the earth.
When pressure builds up, eruptions occur.
In an eruption, gases, and rocks shoot up through the opening and spill over or fill the air with lava fragments.
Eruptions can cause lava flows, hot ash flows, mudslides, avalanches, falling ash and floods.
The sound of an erupting volcano can be quiet and hissing or explosive and booming.
The loud cracks travel hundreds of miles and do the most damage, including hearing loss and broken glass.
There are more than five hundred active volcanoes in the world. Also more than eighty percent of the earth’s surface is volcanic.