The world 's largest historic landslide ( in terms of volume ) occurred during the 1980 eruption of Mount St. Helens , a volcano in the Cascade Mountain Range in the State of Washington , USA . The volume of material displaced was . Directly in the path of the huge mudflow was Spirit Lake . Normally a chilly , the lahar instantly raised the temperature to near . Today the bottom of Spirit Lake is above the original surface , and it has two and a half times more surface area than it did before the eruption
1980 eruption
1980 eruption of Mount St. Helens
Mudflow