The caldera may have blasted out its cryomagma in a single explosive event, or it may have spread its eruptions over time.

An icy supervolcano eruption on Pluto may have left a massive crater on the frozen world

Source: space
Source Link: https://www.space.com/astronomy/pluto/an-icy-supervolcano-eruption-on-pluto-may-have-left-a-massive-crater-on-the-frozen-world