How Volcanoes Work
Discover why some volcanoes ooze gentle lava rivers while others blast mountains apart. Learn to read volcanic peaks, recognize the deadliest eruptive hazards, and see the subterranean engines driving our planet.
Like Duolingo, but for How Volcanoes Work. Tomo turns the whole topic into a game you play five minutes a day, until it actually sticks.
A short one: 11 levels across 2 sections, about 22 minutes end to end, roughly 4 days at five minutes a day. It moves through Reading the Eruption and Hazards and Earth's Engine. It starts from scratch.
Free forever · No credit card · iPhone & Android

Key ideas in How Volcanoes Work
- Volcanic violence depends on how thick the magma is and whether trapped gas can vent smoothly
- Thin, runny magma lets expanding gas escape without building up dangerous pressure
- Thick, sticky magma seals in gas pockets until they blow outward
- Runny magma allows gas bubbles to escape easily to the surface
- Because gas vents continuously, basaltic eruptions produce glowing fountains and slow lava flows rather than violent blasts
- Sticky, silica-packed magma prevents dissolved gas bubbles from bubbling out
- As magma nears the surface, gas tries to expand, building extreme internal pressure
- The trapped pressure finally overcomes the weight of the rock, blasting ash and rock outward like a popped champagne cork
- Effusive 'red' eruptions are characterized by glowing, visible molten rock flowing down the slopes
- Explosive 'gray' eruptions pulverize sticky magma into towering plumes of ash and rock dust that block the sky
- Shield volcano lava is runny and fluid rather than thick and sticky
- Fast-flowing lava travels miles across the ground before solidifying, laying down thin, wide layers
- Stratovolcanoes stack alternating layers of explosive ash and thick, sticky lava plugs
- Shield volcanoes are built by miles of fluid basaltic flows
- Cinder cones are formed from loose lava gravel thrown around a single opening
- Calderas form inward: after a massive eruption empties the underground magma chamber, the roof caves in under its own weight
You've tried the other tabs
Thirty open tabs. Four facts you actually kept.
You watched. You nodded. By Sunday it was gone.
One answer, then back to scrolling.
Eight weeks. You meant to finish. You didn't.
Tomo gives How Volcanoes Work the Duolingo treatment: levels, streaks, and quick quizzes that test what you just learned. That game loop is what the tabs above never had, so it's the one you actually finish.
Here's what playing it feels like
A real question from this course. Take your best guess.
What happens to expanding gas inside thin, runny magma?
Get it right to open this lesson and 10 more in the app.
How to learn How Volcanoes Work, step by step
Go in order. 11 short levels across 2 sections, about 22 minutes in all, five minutes a day.
- 1
Reading the Eruption
- Ooze or Explode: Magma's Two Personalities
- Decoding Mountain Shapes
- 2
Hazards and Earth's Engine
- The Real Killers Beyond Lava
- Where Magma Breaks Through
2 sections · 4 units · 11 levels. Built to play, not to enroll.
Questions about How Volcanoes Work
How do I learn How Volcanoes Work?
Go in order: start with Reading the Eruption, then Hazards and Earth's Engine. On Tomo that's 11 short levels, about 22 minutes in all, played five minutes a day. Start free and play the first level in under a minute.
Is there a Duolingo-style app for How Volcanoes Work?
Yes. Tomo works like Duolingo: short daily lessons, streaks and quick quizzes. How Volcanoes Work is one of its free courses, and you can type any other topic to get a course of your own.
Is the How Volcanoes Work course free?
Yes. How Volcanoes Work is playable on Tomo's free plan, which doesn't expire. No credit card, no waitlist. Download the app and start your first lesson.
How long does it take to learn How Volcanoes Work?
11 levels across 2 sections, about 22 minutes of play in total. It's built for five minutes a day, so you finish it a little at a time instead of all at once.
Do I need any background to start How Volcanoes Work?
No. It's pitched at a beginner level, so it starts where you are and builds up. If you can tap a phone, you can start.
Tomo is in ChatGPT
Tomo is also a ChatGPT plugin: the same playable courses, built and played inside your chat.
Add Tomo to ChatGPT- What to ask
- “Make me a Tomo course on black holes.” “Turn this chat into a Tomo course.”
- What you get
- Quick questions with instant feedback, hearts and stars, ready to play in about a minute.
- Where it goes
- No sign-up to start. Connect your Tomo account and your streak carries on in the app.
You pick the voice
How Volcanoes Work is taught in the Bestie style: your friend who just gets it. Want a different feel? In the app you can spin up the same topic in any of Tomo's teaching styles. Same facts, totally different vibe.
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Start How Volcanoes Work today.
Download Tomo, search How Volcanoes Work, and play your first lesson in under a minute.