In 1953 a lahar swept away a railway bridge at Tangiwai at the base of the mountain and 151 people were killed when an Auckland-to-Wellington train plunged into a river.
In March 2007 a mud flow, or "lahar" flowed down the side of the mountain after the crater lake overflowed, and large eruptions in 1995 and 1996 blanketed the surrounding area in ash.