The violent eruption which killed 1,700 people has never been satisfactorily explained.
More violent eruptions are possible only in unique circumstances, such as an eruption into a lake.
"Clearly, we want to make sure they're taking their medication so there are no violent eruptions in the prison."
All four were swept away in a sudden violent eruption.
Locals evacuated while the violent eruptions continued for three days.
Unfortunately, these measures were too late, and in a violent eruption the nuclear waste exploded.
It represents the most violent eruption in the world in the last 5,000 years.
Suddenly, there was a greater disturbance, a more violent eruption.
But violent eruptions are rare; the most recent of note was in 1996 when four people were hurt.
These rhyolites can be quite hot and form violent eruptions, despite their low water content.