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.
η ≈10⁷ Pa·sVEI 2.3plume 0.0 kmlava 0.0 kmComposite cone
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?