Here's why:

* Explosive: It was a highly explosive eruption, characterized by a massive blast that ejected a huge volume of ash and gas into the atmosphere.

* Column: The eruption generated a towering eruption column that reached an estimated height of 15 miles (24 km).

* Pyroclastic Flows: The eruption also produced deadly pyroclastic flows, fast-moving currents of hot gas and volcanic debris that devastated the surrounding area.

While the eruption exhibited some features of other types like Pelean, the Plinian classification best describes the main characteristics of its explosive nature and the massive column it generated.