Most volcanoes form at the boundaries of Earth's tectonic plates, which are huge slabs of crust and upper mantle that fit together like puzzle pieces. Think of these plates as massive rafts floating ...

(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.

Volcanoes in Alaska, Washington state, Oregon and Hawaii have been rumbling and even spewing lava, enough to spark a swarm of news stories. But despite the jolts and temblors, geologists say there's ...

The 1980 eruption cycle made Mount St. Helens one of the most famous and now best-monitored volcanoes in the Cascades. But it is far from the only volcano in the range. From southern British Columbia ...

Volcanoes, awe-inspiring natural phenomena formed by the Earth’s tectonic processes, dot the globe in regions where tectonic plates converge or diverge. The United States holds the record for the most ...

Lava is molten rock from a volcano that reaches the Earth’s surface. Liquid rock below the Earth’s surface is referred to as magma. More than 50% of the world’s active volcanoes above sea level ...