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A Closer Look at the World's 9 Most Active Volcanoes
Volcanoes have been responsible for many natural disasters throughout history. Here are the top nine most active volcanoes that pose the greatest risks to humanity.
Science & Tech
Volcanoes rank right up there in the world's arsenal of powerful forces.
Scientists define an active volcano as one that has erupted in the last 10,000 years.
Based on this definition, the earth has around 1,500 active volcanoes spread across the globe. Around 75 percent of those are located along the pacific ring of fire – a region that spans the perimeters of landmasses on the Pacific ocean.
Why do volcanoes form and erupt?
All volcanoes form through the basic process of magma working its way up through the earth's mantle and crust. As the magma works its way through to the surface, it eventually breaches and starts to harden. This hardening of magma over and over causes the formation of a taller or wider volcano.
The source of this magma comes from deep within the earth. It's so hot near the earth's core that rocks melt and become a thick flowing substance, what we know as magma. As the rocks melt into magma, its density actually changes to become lighter than the solid rocks around it.