What are volcanic eruptions?

A volcanic eruption is when molten rock from inside the Earth comes out and makes a big mess on the surface.

Imagine you have a giant bottle of hot chocolate that’s been sitting in the microwave for too long. The lid is on tight, but the inside is bubbling and boiling. Then, pop!, the lid flies off, and the hot chocolate sprays everywhere. That's kind of what happens with a volcano.

Deep underground, there’s molten rock, which we call lava. It's like super-heated soup made of rocks and gases. When pressure builds up inside the Earth, it pushes this molten rock upward through a tube, called a pipe, until it finally breaks out at the top.

When the lava comes out, it can flow down the sides of the volcano like a hot river, or it can shoot up into the air with big clouds of smoke and ash. Sometimes, rocks are thrown far away, like when you throw marbles from a high place. This is why volcanoes can make new land, like islands, and change the shape of the Earth forever!