The most violent type of volcanic eruption is a Plinian eruption. This type can produce plumes of ash that are more than 30 miles high.
Plinian eruptions result from massive amounts of pressure built up by expanding gases inside the volcano. This pressure expands until there is no more room, and the volcano erupts the material into the air.
Plinian eruptions are named after Pliny the Younger, a Roman statesman who authored a piece depicting the details of the eruption of Mt. Vesuvius in 79 A.D. This eruption resulted in the deaths of thousands of civilians and the destruction of Pompeii and Herculaneum.