Volcanoes

A volcano is an opening the the earth's crust that allows energy to escape from below the crust. This can come in the form of gas, ash, dust or even molten rock. Volcanoes can build into great mountains over time, and they can also explode violently.

One famous volcanic event is the eruption of Mount Vesuvius in Italy, which buried the cities of Pompeii and Herculaneum in 79 AD.

For more on natural disasters, see the features on Earthquakes, Hurricanes, Tsunamis, and Weather.