The Earth consists of three layers. The outer layer of Earth we live on is called the crust. It’s about 18 miles thick.

Below the crust lies an 1,800-mile thick layer called the mantle. A combination of molten rock and gases called magma lies between the Earth’s crust and the mantle. The innermost layer is called the core.

A volcano is a mountain that extends down to a pool of magma between the crust and mantle. It’s basically a hole in the Earth from which magma can erupt. The name “volcano” comes from the name of Vulcan, a god of fire in Roman mythology.

Volcanoes are like huge safety valves that release the pressure that builds up inside the Earth. When pressure builds up, eruptions occur. Magma shoots up through the volcano and flows down its sides. When magma flows out of a volcano, we call it lava. Fresh lava can be as hot as 2,200° F, glowing red or white as it flows.

Eruptions can cause mudslides, avalanches, and floods. Volcano eruptions have knocked down entire forests and triggered tsunamis and earthquakes.

As they erupt, volcanoes spew huge clouds of volcanic ash into the atmosphere. The ash consists of tiny bits of rock and glass. Ash clouds can cover hundreds of miles, creating problems for airplanes and changing weather patterns. Volcanic ash can also damage the lungs and cause other respiratory problems for those who breathe it.

The United States contains several active volcanoes, mainly in Hawaii, Alaska, California, Oregon, and Washington. Hawaii and Alaska have the greatest chance of experiencing eruptions near areas where many people live.

Here are some interesting facts you may not know about volcanoes:

  • Historical records exist for almost 600 volcanoes around the world, while some scientists believe there are over 1,500 active volcanoes! No one really knows for sure how many volcanoes exist under the oceans.
  • Over half of the world’s volcanoes arise in a belt around the Pacific Ocean called the Ring of Fire.
  • On any particular day, approximately 20 volcanoes are in the process of erupting.
  • The “danger zone” of a volcano extends for up to 20 miles in all directions.
  • On May 18, 1980, Mount St. Helens erupted in Washington, killing 58 people and causing over $1 billion in property damage.

68 Join the Discussion

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    • When there is an earthquake the volcano will erupt and lava, gas, and ash will cover the sun and the inside of the earths crust and molten will sheer and tear and the lava will came it’s way to the surface and thats how volcano erutps and if you are a space you can see the gases and ashes in space. Volcanoes are in the ocean but volcanoes erupt the water is hot and bubbling and comes out of the ocean water and volcano’s create land. And volcano’s erupts and rock and some are the size of bolder and some times it’s sleeping and some are not.

      • It sounds like you have a LOTS of background knowledge, Anthony. Thank you for sharing with us today! We hope you have a WONDERful day! We look forward to seeing you again soon! :)

    • Thank you so much for sharing your personal connection to this Wonder, Natasha, and also for being a GREAT Wonder Friend! :-)

  1. As I was reading this, I was thinking of how scary this can be for my own ties to mother earth and father land in nature [at least one home state]. This is a true wonder of the day!!

    • Thanks for sharing your comment about volcanoes, Anonymous Wonder! We appreciate your response and we are glad that we can Wonder together about the Earth’s resources and natural formations! We hope you have a WONDER-filled day! :)

    • Hey there, Hazem! We’re so happy that Wonderopolis is helping you to Wonder on your own! We Wonder what kind of project you worked on, Hazem? We’d LOVE to hear about your awesome work! :)

    • We agree, Jacob! We LOVED watching the volcano experiment, too! Thanks for joining the fun at Wonderopolis! So glad you’re here! :)

      • Welcome back to Wonderopolis, Wonder Friend Daivionne! It sounds like you are really interested in volcanoes. We encourage you to do some WONDERing about volcanoes on your own to answer your questions. Happy WONDERing! :)

    • Thanks, Gage! Have you ever tried a volcano experiment in class like that? If you could build a fake volcano, how big would you try to make it? Have a WONDERful day, friend! :)

    • Hi Joey! Thanks for WONDERing with us! We’re so glad that you’re enjoying WONDERopolis and WONDERing about life with us! :)

    • Super question, Wonder Friend Lyrik! We think that’s a great WONDER to explore on your own. We’d LOVE for you to let us know what you find out. Happy WONDERing! :)

    • We’re SO HAPPY to have you WONDERing with us today, Sian Pi! Thank you for summarizing the answer to today’s Wonder. We hope you have a WONDERful day! :)

  2. In my world(Porcucity which is a porcupine city), I live in a volcano. The volcano has spikes. I call it Porcucano. Wonderopolis, imagine dwelling in a volcano for a living. I love volcanoes. I can survive because I am magma proof.

    • We think this sounds like a WONDERful start to a fiction story, Lawrence! Thanks for sharing! We hope you WONDER with us again soon! :)

    • How COOL, Roman! Thank you for sharing some things you noticed about this Wonder of the Day! Thank you for spending time WONDERing with us today! :)

    • Woohoo! We’re so glad you found Wonderopolis, Nicole! Thanks for spreading the word to your teacher – we hope to see you again very soon! :D

    • We are glad you found this WONDER interesting, Mason! Maybe you could learn more about Mt. St. Helen at your library. Keep WONDERing! :)

    • Hi, shea’vonda cherry! Thanks for WONDERing with us! There is a new Wonder of the Day every day for you to explore. Visit again soon! :)

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Have you ever wondered…

  • What is a volcano?
  • Where does lava come from?
  • Are there any active volcanoes in the United States?

Wonder Gallery

volcano smoking_shutterstock_66225952erupting volcanohhVimeo Video

Try It Out

Did today’s Wonder of the Day cause a build-up of pressure inside you as you longed to explore volcanoes further? Don’t blow your top! Just grab a friend or family member and check out one or more of the following fun activities:

  • Have you ever seen a volcano up close? You might not live in an area with volcanoes, but that doesn’t mean you can’t use modern technology to your advantage. Jump online to see some great video clips of volcanic activity on Hawaii. Head on over to the video gallery to see what’s happening at the Kilauea volcano!
  • Think you might want to be a geologist someday? Want to keep a closer eye on volcanoes? Jump online to visit Volcano Live to access links to live volcano webcams across the world. Keep a journal of your observations. What do you notice about the volcanoes? How are they similar? How are they different? Choose one particular volcano and keep an eye on it for an extended period of time. What changes do you notice?
  • Up for a challenge? Create your own volcano! Visit the Volcano Models resource page for step-by-step instructions for how to make different types of volcano models for every age and skill level! If you can, videotape your volcano erupting and upload it to the Wonderopolis SchoolTube video channel. We’d love to see your volcano in action!

Still Wondering

So where do people face the greatest danger from earthquakes and volcanoes? Visit National Geographic Xpeditions’ The Power of Fire activity to learn a bit about plate tectonics and create a map that shows where these natural hazards are most likely to occur.

Test Your Knowledge

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