(CNN) — Here's some background information about volcanoes, mountains that open downward to a reservoir of molten rock. Facts: More than 80% of the Earth's surface, both above and below sea level, is ...

Volcanoes can look like small mountains or hills. A volcano is an opening in the Earth's crust that allows magma, hot ash and gases to escape. Composite volcanoes are the most common type of volcano.

An eruption forecast is a probabilistic assessment of the likelihood and timing of volcanic activity. The forecast may also include information about the expected style of activity (Section 1.6), the ...

Some volcanoes erupt with little to no warning, posing serious risks to nearby communities and air traffic. A study of Alaska's Veniaminof volcano reveals how specific internal conditions like slow ...