1. Before the volcano erupts, the water can get all dirty with sulfur dioxide.

2. The sulfur dioxide, and the fact that the volcano may erupt any time means that they should evacuate.

3. When ash gets in the helicopters engine, it doesn't function right so you will crash and die.

4. An earthquake occurred before the volcano erupted.

5. The town had a meeting in the high school gym before they evacuated but Dante's Peak erupted before they could even finish the meeting.