From Vesuvius to Laki, we've seen some monstrous eruptions of volcanoes throughout history. Most of these volcanoes are stratovolcanoes, meaning cone-shaped elevations that were built over time from layers of ash and lava. Due to their relatively soft composition, pressure builds up inside until they blow up, which results in sudden explosive eruptions. Their steep slopes then generate pyroclastic flows, making them some of the most dangerous types of volcanoes.
The power of such eruptions is measured using the Volcanic Explosivity Index (VEI), which is a scale that goes from one to eight. Each succeeding VEI is 10 times greater than the last.
Need examples? Click on for some of the worst volcanic eruptions in history.