Why are some volcanoes more explosive than others?

Some volcanoes blow their tops harder because they have different kinds of lava inside them.

Imagine you're filling a balloon with water, it just squishes and stretches. But if you fill it with honey, it's thick and sticky, making the balloon bulge more before it pops. That’s like what happens in volcanoes: the thicker the lava, the more pressure builds up, and the bigger the explosion.

Lava is made of melted rock, but not all lava is the same. Some lava has a lot of stuff mixed in, like sand or tiny rocks, making it thick, almost like syrup. This kind of lava is called viscous. It moves slowly and traps gas inside, which builds up pressure.

Other lava is runnier, more like water. That’s because it has fewer bits mixed in. This kind of lava is called less viscous. It flows easily, letting gas escape gently, no big explosions needed.

So, the next time you see a volcano, think about whether it has syrupy lava or watery lava, that might tell you how big its eruption will be!