Why Do Volcanoes Erupt Like Clockwork?

Volcanoes can erupt like a clock because they have a hidden timer inside them. Imagine you're filling up a balloon with water, once it gets too full, poof! It bursts. A volcano is kind of like that balloon, but underground. When magma (hot melted rock) builds up in the Earth’s crust, it puts pressure on the ground above it. After some time, the pressure becomes so strong that the volcano erupts, just like a balloon bursting. Some volcanoes go off at regular times because their timers reset every few years.