- Who
- Mount St. Helens eruption
- What
- 2800000000 square metre(s)
- Where
- United States (Mt St Helens)
- When
The landslide on Mt St Helens on 18 May 1980, was the largest ever observed by a survivor, when about 2800million m3 96,000million ft3 of rock slipped off the mountain immediately prior to the volcanic eruption.
This is equivalent to a block of earth nearly one and a half kilometers high, wide, and long (0.8 miles high, wide and long).