1. The 1985 Mount St. Helens eruption was the biggest volcanic
eruption that ever occurred.
2. All volcanic eruptions involve explosions.
3. A volcanic eruption may be more powerful than a nuclear explosion.
4. Gases form in a volcano when magma boils and evaporates.
5. Ash from a volcanic eruption may stay in the atmosphere for years.
6. Gases from a volcano may cause environmental problems.
7. A volcano is more likely to be explosive when lava is thin and runny.
8. When a'a lava cools, it forms lava tubes.
9. Pillow lava is especially common along mid-ocean ridges.
10. A volcano's history can help scientists predict whether the volcano
is likely to erupt again.