(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 ...

This is read by an automated voice. Please report any issues or inconsistencies here. Mexican scientists have created the first three-dimensional map of Popocatépetl’s interior, revealing multiple ...

POPOCATÉPETL VOLCANO, Mexico (AP) — In the predawn darkness, a team of scientists climbs the slope of Mexico’s Popocatépetl volcano, one of the world’s most active and whose eruption could affect ...

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 ...

POPOCATÉPETL VOLCANO, Mexico — In the predawn darkness, a team of scientists climbs the slope of Mexico’s Popocatépetl volcano, one of the world’s most active and whose eruption could affect millions ...