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. Magma is molten rock - rock that is so hot it has ...

Millions of people around the world live near one of the roughly 1,500 active volcanoes on Earth—from Italy’s Campi Flegrei to Indonesia’s Merapi to the United States’ Mount Rainier.