<p>The Tungurahua volcano erupts in the night. Tungurahua, also called the Black Giant, is one of Ecuador's most active volcanoes.</p>

The Tungurahua volcano erupts in the night. Tungurahua, also called the Black Giant, is one of Ecuador's most active volcanoes.

Photograph by Ammit/ Alamy

Volcanoes, explained

These fiery peaks have belched up molten rock, hot ash, and gas since Earth formed billions of years ago.

Volcanoes are Earth's geologic architects. They've created more than 80 percent of our planet's surface, laying the foundation that has allowed life to thrive. Their explosive force crafts mountains as well as craters. Lava rivers spread into bleak landscapes. But as time ticks by, the elements break down these volcanic rocks, liberating nutrients from their stony prisons and creating remarkably fertile soils that have allowed civilizations to flourish.

There are volcanoes on every continent, even Antarctica. Some 1,500 volcanoes are still considered potentially active around the world today; 161 of those—over 10 percent—sit within the boundaries of the United States.

But each volcano is different. Some burst to life in explosive eruptions, like the 1991 eruption of

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