An eruption column consists of hot volcanic ash emitted during an explosive volcanic eruption. The ash forms a column rising many kilometres into the air above the peak of the volcano. In the most explosive eruptions, the eruption column may rise over 40 km, penetrating the stratosphere. Stratospheric injection of aerosols by volcanoes is a major cause of short-term climate change.

A common occurrence in explosive eruptions is for column collapse to occur. In this case, the eruption column is too dense to be lifted high into the air by air convection, and instead falls down the flanks of the volcano to form a pyroclastic flow or surge.