Where did the change begin?
Labs / Geography
What Makes a Volcano Erupt
Press and hold the volcano to pump magma into the chamber, then let go to erupt. Sticky, silica-rich magma traps its gas and blasts an ash plume into the sky, while runny, low-silica magma simply oozes lava down the flanks. Nudge the sliders and watch the volcano's whole shape change.
Labs / Geography / What Makes a Volcano Erupt
What Makes a Volcano Erupt
Press and hold the volcano to pump magma into the chamber, then let go to erupt. Sticky, silica-rich magma traps its gas and blasts an ash plume into the sky, while runny, low-silica magma simply oozes lava down the flanks. Nudge the sliders and watch the volcano's whole shape change.
Why it matters
Why explore this?
Geography explains how places, people, and Earth systems affect one another. This model lets you change one factor and watch its effects spread across space.
Explore
Try the model
η ≈10⁷ Pa·sVEI 2.3plume 0.0 kmlava 0.0 kmComposite cone
Investigate
Questions to test
Predict first, try it in the model, then use what you observe to answer.
What to try
- Crank silica and gas both to the top. Why does trapping gas inside sticky magma turn a quiet mountain into an explosive one?
- Slide silica all the way down. Where does the erupted material go now — up as ash, or out as flowing lava?
- Try high gas with very low silica. Can you build much pressure, or does the gas keep leaking away?
- Watch the cone. What makes a shield volcano so wide and flat, while a stratovolcano grows tall and steep?
- Compare the Basalt, Andesite, and Rhyolite presets. Which real volcanoes — Hawaiian shields or Cascade peaks — does each one remind you of?
Explain
Make sense of what happened
Connect the pattern to place: identify where the change begins, where its effects appear, and which process links those locations.
Check
Before you leave
What spatial pattern appeared?
Which process connects the cause and effect?
If you can answer all three using evidence from the model, you understand the main idea. If not, return to Explore and change one setting at a time.