10 Volcano Facts

Here are some key facts about volcanoes.

  • Volcanoes are vents or cracks in the Earth’s surface through which hot gases, molten rock and debris are emitted. There are about 1,900 volcanoes in the world.

  • Volcanoes can be either active, dormant or extinct. An active volcano has erupted during the last 1,000 years and is likely to erupt again, a dormant volcano has not erupted recently and an extinct one is unlikely to erupt again.
  • There are about 100 active volcanoes in the US, and the one most likely to erupt is Mount Rainier. However, the country with the most active volcanoes is Indonesia with about 160.
  • Most volcanoes form over thousands of years, although they can also appear very quickly. In 1943, a volcano named Paricutin appeared in a Mexican field and was about 60 feet tall in a week, growing to a height of 1,000 feet in a year.
  • There may be as many as 10,000 volcanoes on the ocean floor. One of the most famous is Surtsey, off the coast of Iceland, which erupted and formed a new island in 1963; the island is now home to thousands of seals and seagulls.
  • Around the world, about 5 million people live close to active volcanoes. One of the most famous is Mount Vesuvius in Italy, and several million people live dangerously close to it.
  • One of the most devastating volcanic eruptions was the 1883 eruption of Krakatoa, which killed about 36,000 people. The eruption made one of the loudest sounds ever heard and had the strength of 15,000 nuclear bombs.


  • Hawaii and Iceland are both volcanic islands, and because of this they have black beaches. The sand is actually made from the lava cooling down, creating a rock called basalt.
  • In Iceland and other volcanic areas, the heat from volcanoes is used to run power plants and produce hot water. In Japan, many people bathe in warm volcanic sand to cure various illnesses and skin conditions.
  • The farmland around volcanoes is some of the most fertile in the world, because of the nutrients present in the volcanic ash. One species of bird, the maleo, incubates its eggs by using the heat from volcanic sand.

What next? Vistit the Primary Facts resouces page on Volcanoes.

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