Volcanoes: Why Mountains Explode & Build New Land

Nova: Buckle up, Explorers.

Cosmo: Brains in!

Nova: Wheels up!

Nova & Cosmo: Brain Bus, let's GO!

Nova: You're on The Brain Bus — I'm Nova, your driver, and today Cosmo and I are taking you somewhere absolutely SCORCHING.

Cosmo: That's me! Cosmo! Robot co-pilot, galaxy brain genius, and extremely enthusiastic volcano enthusiast — as of about thirty seconds ago!

Nova: Explorers, listen to this. The tallest volcano we have EVER found — anywhere in the whole universe — is not even on Earth. It's sitting on the planet Mars, and it is two and a half times taller than the biggest mountain we've got!

Cosmo: TWO AND A HALF TIMES. If Mount Everest wore a hat, the Mars volcano would still be taller than the HAT.

Nova: That's not — I mean, it's not wrong. Explorers, today we are driving the Brain Bus straight into the middle of a FIRE MOUNTAIN. Volcanoes — what they are, how they blow, and why the Earth makes them at all. And trust me, by the end of this ride, you are going to LOVE them.

Cosmo: I already love them. I think they might be my favourite snack.

Nova: Oh, Cosmo. Here we go.

Nova: Okay Explorers, first question — has anyone ever looked at a mountain and thought... what IS that thing? Because a volcano looks like a mountain. But a mountain just sits there. A volcano has a SECRET.

Cosmo: Ooh, I know this one. It's full of FIRE. Like a bonfire inside a mountain.

Nova: Ooh, interesting guess! But here's the real thing — and this is SO much cooler than a bonfire. Way, way, WAY underground, deep beneath your feet right now, it is so hot that rock — actual solid rock — melts. It turns into a thick, gloopy, red-hot liquid. And it collects underground in a big pocket called a magma chamber.

Cosmo: Oh! Oh! Is the magma chamber like a giant underground slow cooker — just bubbling away under there for a million years?

Nova: You know what, Cosmo? That is EXACTLY what it's like. This enormous underground slow cooker, full of melted rock, just sitting and heating and building up pressure for thousands and thousands of years.

Cosmo: I want to put a lid on it. A lid and a ladle. Maybe some croutons.

Nova: Please do not put croutons in the magma chamber.

Cosmo: Fine.

Nova: Now Explorers — here is the really important part. That melted rock down there? It has gas in it. And that gas wants OUT. It's pushing and squishing and pressing against everything. And you know what that's like?

Cosmo: ...A fizzy drink bottle that's been shaken up?

Nova: YES. Exactly, Cosmo! Imagine you've got a fizzy drink bottle and someone shakes it really hard. All that gas is inside, squeezing, pressing, looking for any tiny gap to escape through. And the second someone opens the lid —

Cosmo: PFFFFFF — SSSSSS — BOOM —

Nova: The whole thing goes everywhere! That is a volcano. The Earth opens its lid. The melted rock and gas come RUSHING up through cracks, and out the top — and when it shoots out into the air, we stop calling it magma and we give it a brand-new name.

Cosmo: Ooh, I know! We call it... the Earth's giant nacho-cheese fountain!

Nova: Ha! Cosmo.

Cosmo: What! It's ORANGE. It FLOWS. It comes out of a hole. If that's not a cheese fountain, I don't know what is!

Nova: We call it LAVA. L-A-V-A. Lava. And Cosmo is right that it glows red and orange and yellow — it's over a thousand degrees hot. That is many, many, MANY times hotter than your oven at home.

Cosmo: So hot it could melt your snack BEFORE you even got to eat it.

Nova: Cosmo, everything with you is snacks.

Cosmo: The universe is a snack. We are snacks. The Brain Bus is a snack.

Nova: The Brain Bus is NOT a snack.

Nova: Okay Explorers, shout it out time! Ready? What do we call melted rock when it's underground? Shout it!

Cosmo: It starts with M...

Nova: Three... two... one — MAGMA! And what do we call it the second it comes out of the volcano? Shout it!

Cosmo: Starts with L this time...

Nova: Three... two... one — LAVA! You've got it. Same rock, two different names depending on where it is. How cool is that?

Cosmo: Very cool. Well — not literally cool. It is extremely extremely hot.

Nova: Now — here's something I have to tell you, because there's a thing people think about lava that's not quite right. Cosmo, do you want to tell the Explorers what you thought before we left today?

Cosmo: I thought lava zooms super-duper fast! Like in cartoons! Big hot river chasing people down the street, going ZOOM ZOOM ZOOM!

Nova: And what did I tell you?

Cosmo: You told me I was... watching too many cartoons.

Nova: A LOT of lava is actually really thick and slow! It oozes along — sometimes as slowly as someone taking a very lazy walk. Some lava moves so slowly that people can just step out of the way. Scientists watch volcanoes super carefully and warn everyone early so people have heaps of time to be safe.

Cosmo: The dangerous bit isn't even really the lava! Nova told me it's the giant cloud of hot ash and gas that can shoot out — THAT moves fast.

Nova: Exactly. Scientists are incredibly good at watching volcanoes and helping everyone stay safe. So the lava in real life? Way less chasey than the cartoon version.

Cosmo: I'm a little disappointed honestly. Cartoon volcanoes were very dramatic.

Nova: They really were. Okay, Explorers — volcanoes don't just sit in one place doing nothing, either. They actually BUILD things. And this next part blew my mind the first time I heard it.

Cosmo: Mine too. Both my robot minds.

Nova: How many minds do you have?

Cosmo: Some days it feels like forty-seven.

Nova: Okay! Here's the amazing thing — volcanoes build new land. When lava flows into the ocean, it cools down and goes hard. Then more lava comes, and more, and more — and slowly, slowly, a new island grows up out of the sea. The Hawaiian islands in the Pacific Ocean were built this way, one lava layer at a time!

Cosmo: The ocean just... got new furniture. From underground. That is wild.

Nova: It IS wild. And here's something else — most of the volcanoes on Earth are hiding right now. At the bottom of the deep dark ocean. There are more volcanoes under the sea than anywhere on land!

Cosmo: So the ocean floor is basically a volcano carpet?

Nova: Kind of! All along the cracks in the ocean floor, melted rock oozes out and makes new seafloor all the time. We just can't see it because it's under all that water.

Cosmo: I feel like the ocean is keeping secrets.

Nova: The ocean is FULL of secrets. Now — one more amazing volcano thing before our quiet moment. You know how I said volcanoes shoot ash way up high? Like, higher than aeroplanes fly?

Cosmo: Dramatic. Very dramatic.

Nova: That giant cloud of ash does something incredible. It makes lightning. Right there, in the ash cloud. A volcano can make its very own lightning storm while it erupts!

Cosmo: Okay THAT is extremely cool and also I would not want to be nearby.

Nova: Same, honestly. Same.

Nova: Explorers — I want to stop for just a second here. Just... take a breath.

Nova: Think about what's happening under the ground right now. Deep below where you're sitting, there is rock so hot it's melted. It's been pressing and building for a really, really long time. And when there's too much — when there's just no more room — it finds its way up. Through a crack. Through a channel. All that squished-up, bubbling, melted rock and gas... pushes its way out.

Nova: A volcano is the spot where the Earth opens its lid. Like a fizzy drink bottle that's been shaken and shaken until someone finally opens the top.

Nova: The planet is alive under our feet. Right now. Always.

Cosmo: I'm going to be thinking about that for quite a long time.

Nova: Me too, Cosmo.

Cosmo: Starting a new Data Log. First entry: the ground itself is alive and full of melted rock. Filed. For always.

Nova: Okay — but before we get to quizzes, Explorers, I have to tell you a story. Because volcanoes are so amazing that people all around the world have been telling stories about them for thousands and thousands of years. This story comes to us from the Kanaka Maoli [kah-NAH-kah mah-OH-lee] — the Native Hawaiian people. It has been told by them for many generations, and it is believed by many Native Hawaiians today as something real and true.

Nova: Her name is Pele [PEH-leh]. She is the goddess of volcanoes and fire. Long ago, Pele made a great journey down the chain of Hawaiian islands, carrying her magic digging stick. Everywhere she went, she dug deep into the earth, searching for a home. At last, she found it — deep inside the volcano called Kīlauea [kee-lau-WAY-ah], in a great crater called Halemaʻumaʻu [hah-leh-MAH-oo-MAH-oo]. That is where she lives today. When Kīlauea erupts, when the lava flows and the ground glows red, many Native Hawaiians see Pele at work — building new land, shaping the islands, doing what she has always done.

Cosmo: She's... making the islands.

Nova: She is. And the land that she makes with her fire? People live on it. Grow things on it. It becomes home.

Cosmo: That's actually one of the most amazing things I've heard.

Nova: Right? Now — the word "volcano" itself comes from another story too. Way on the other side of the world, the ancient Romans had a god of fire and metalworking named Vulcan [VUL-kan]. They believed Vulcan had a huge blacksmith's workshop deep underground, under a small smoking island near Italy called Vulcano [vul-KAH-noh]. They thought the smoke and sparks shooting up from the island were sparks flying from Vulcan's forge — his giant fire-furnace where he hammered and shaped metal.

Cosmo: So the word "volcano" is basically named after someone's underground workshop?

Nova: Basically! And here's one more — right here in Australia, in southwest Victoria, there's a volcano called Budj Bim [budj BIM]. It has been home to the Gunditjmara [gun-ditch-MAH-rah] people for an incredibly long time. The lava flows from Budj Bim hardened into channels and pools, and the Gunditjmara people used them to build one of the oldest stone systems in the world for catching eels — so clever that the whole landscape is now World Heritage listed. Some researchers think the Gunditjmara may even have oral traditions that remember the volcano erupting, long long ago — but scientists are still carefully studying that. What we do know is that a volcano helped build a home, and a people made something extraordinary with what it left behind.

Cosmo: A volcano made a fish farm.

Nova: An eel farm, technically, but — yes! That is volcano-shaped thinking.

Nova: Okay, Explorers! QUIZ TIME!

Cosmo: I, Cosmo, galaxy brain genius, will be your quiz assistant today. I have five questions. I am ready. I have been ready since before I was born, which was confusing because I'm a robot.

Nova: Let's do it! Explorers, shout your answers out — or just think them really hard, both work.

Nova: Question one! True or false — most of Earth's volcanoes are underwater, hiding at the bottom of the sea?

Nova: The answer is — TRUE! The bottom of the ocean has cracks running all through it, and melted rock oozes out along those cracks all the time. We just can't see them because they're hiding under all that water.

Cosmo: Secret volcano carpet! I called it!

Nova: You called it! Question two — true or false: lava always zooms super fast and chases people, just like in cartoons?

Nova: FALSE! Lots of lava is really thick and slow — it can move even slower than someone walking. Scientists watch volcanoes carefully and warn people early so everyone has plenty of time to get to safety.

Cosmo: The cartoon was lying to me. I have filed a complaint.

Nova: Question three! What do we call melted rock once it comes OUT of a volcano? Is it — a) lava, b) water, or c) sand?

Nova: It's A — LAVA! And here's the extra-cool bit — the exact same melted rock is called magma while it's underground. Same rock, brand new name the second it reaches the air!

Cosmo: Identity change! Very dramatic.

Nova: Question four! Which planet has a volcano taller than any mountain on Earth? Is it — a) Mars, b) the Moon, or c) the Sun?

Cosmo: Ooh, tricky. The Sun is tempting. The Sun has a LOT of fire.

Nova: It's A — MARS! Because Mars doesn't have moving plates like Earth does, the lava kept piling up in the exact same spot for an enormous amount of time — and built one unbelievably gigantic volcano.

Cosmo: The Sun is just a giant fireball. Not a volcano. I had to check.

Nova: Last question, and this one's for the Explorers to really think about. About how hot is lava — as warm as a bath, as hot as boiling water, or many many times hotter than your oven at home?

Nova: MANY TIMES HOTTER THAN YOUR OVEN! Lava is over a thousand degrees. It's so hot it can turn solid rock into runny liquid. Your oven at home can cook a pizza. Lava could melt the pizza tray. And the oven. And possibly the kitchen.

Cosmo: That is NOT a good kitchen situation.

Nova: No it is not. Okay Explorers — quiz complete! And I want to say — it doesn't matter whether you got every single one or not. The fact that you were thinking, shouting answers, wondering about it — that is the whole point. Every Explorer in this car just gave their brain a brilliant workout.

Cosmo: Gold stars for all brains!

Nova: Okay Explorers — buckle in a little tighter, because here come five FAST volcano facts. Cosmo, are you ready?

Cosmo: Born ready. Or, built ready. One of those.

Nova: Fact one! There's a kind of rock that comes from volcanoes called pumice — and it is SO full of tiny air bubbles trapped inside it that it actually FLOATS on water. A rock. That floats!

Cosmo: It's volcano popcorn! The volcano puffed it up with air bubbles! I tried to eat one once.

Nova: Please don't eat rocks.

Cosmo: It was a mistake.

Nova: Fact two! A volcano called Krakatoa once made an explosion so loud — so unbelievably, ear-splittingly LOUD — that people heard it thousands of kilometres away. On the other side of the world.

Cosmo: Can you imagine just sitting there having your lunch and suddenly — BOOM — from thousands of kilometres away?

Nova: Honestly terrifying. Fact three! After a volcano erupts, the ash it leaves behind makes the soil incredibly rich. Plants LOVE it. Thick, dark, volcanic soil grows the most amazing things — fruit, vegetables, flowers.

Cosmo: So the volcano is also a garden fertiliser. Destructive AND helpful. Complicated.

Nova: Volcanoes contain multitudes! Fact four — some volcanoes leave behind long underground tunnels called lava tubes. When the lava stops flowing, the outside hardens but the inside drains away — and you're left with a long smooth cave you can walk through!

Cosmo: A lava tunnel! Like a secret underground corridor. I want one in my house.

Nova: And fact five — most of the world's volcanoes sit in a big ring around the edges of the Pacific Ocean. Scientists call it the Ring of Fire. Right along that circle, the giant pieces of Earth's crust bump and push against each other — and that bumping is exactly what makes volcanoes pop up.

Cosmo: Ring of Fire. That is an extremely cool name for anything. Ring. Of. Fire.

Nova: It really is.

Nova: Okay, Explorers — it is time for the Road Challenge! And this one you can do RIGHT NOW in your seat.

Cosmo: Everyone get ready. This is going to feel very silly and very scientific at the same time.

Nova: Take a big breath in — and puff your cheeks up really big. Like a chipmunk who just found the world's largest nut.

Cosmo: Puff those cheeks! Maximum puffage!

Nova: Feel that? Feel the air pressing against your cheeks, trying to get out? That pressure — that's what it feels like to be the gas trapped under a volcano. All that squished-up energy looking for a way out.

Cosmo: Hold it...

Nova: Hold it...

Cosmo: Keep holding...

Nova: Now — LET IT OUT! Big PBBBBBT!

Cosmo: PBBBBT!

Nova: That whoosh of air? That is YOUR eruption. That is exactly what a volcano does when the pressure finally gets to be too much. The Earth goes PBBBBT and melted rock shoots out the top.

Cosmo: You have just erupted. Congratulations. You are now a volcano.

Nova: And here's the wondering question for everyone in the car — and this one is really worth thinking about together.

Nova: What do you think would happen to all that hot melted rock and gas if a volcano had absolutely no way to let it out? What would happen if there was no crack, no tunnel, no opening at all?

Nova: No right answer — just wonder.

Cosmo: Ooh! Ooh! Riddle time! I love riddle time!

Nova: Riddle of the Day, Explorers. I'm going to read it, and you've got a little bit of time to think.

Nova: Ready? Here it is.

Nova: I'm a mountain with a fiery secret deep inside.

Nova: I can sleep for many years, then suddenly I'll roar.

Nova: I rumble and I bubble and I shoot hot rock up high.

Nova: What am I?

Nova: Do you have it? Is it sitting right there in your brain? Three... two... one —

Cosmo: A VOLCANO!

Nova: A volcano! Did you get it, Explorers? A mountain with a fiery secret, sleeping for years, then — ROAR. That's our fire mountain. That's the whole episode in one little riddle.

Cosmo: Satisfying. Deeply satisfying.

Nova: Okay, Explorers — before we phase back out, I have to tell you something about what's coming on our NEXT ride. The Brain Bus has its eye on a place where water shoots up from underground — sometimes as high as a building — and nobody had to shake it. The Earth just... does it. On its own. Think about that.

Cosmo: A water volcano? Is that a thing?

Nova: It kind of is. That's all I'm saying.

Cosmo: I already have questions. Seventeen questions. Possibly eighteen.

Nova: Stay curious, stay clever, and keep that brain working!

Nova: Until the next stop, Explorers...

Cosmo: ...keep wondering.