Volcano

earth science · plate tectonics · natural forces · geology

Melted rock from below. Deep underground, extremely hot melted rock called magma sits in chambers beneath Earth's surface. When pressure builds up, this magma forces its way up and out through cracks in the crust, becoming lava when it reaches the surface.

Most volcanoes are underwater. You might think volcanoes are all on land, but most of Earth's volcanoes are actually hiding on the ocean floor. These underwater volcanoes form where tectonic plates are spreading apart or colliding.

Plate collisions make explosions. When tectonic plates crash into each other, they create the most dramatic and explosive volcanoes. The Pacific Ring of Fire, which circles the Pacific Ocean, is famous for having some of Earth's most violent volcanic eruptions.

Islands from hotspots. Some volcanoes aren't at plate edges at all. They form over hotspots, which are plumes of super hot material rising from deep inside Earth, creating chains of volcanic islands like Hawaii.

Gentle vs. violent eruptions. Volcanoes at spreading plate boundaries usually erupt gently, while volcanoes at colliding plate boundaries tend to be much more explosive and dangerous.