Logo link to homepage

Global Volcanism Program | Image GVP-05491

The 1980 eruption of Mount St. Helens dramatically altered the conical profile of the volcano. The eruption left a 2 x 3.5 km wide horseshoe-shaped crater, seen here from the NNE beyond Spirit Lake (center). The landslide of 18 May lowered the summit by 400 m and produced a highly mobile debris avalanche that swept into Spirit Lake and traveled down the North Fork Toutle River. The associated northward-directed lateral blast devastated about 600 km2. Photo by Lyn Topinka, 1981 (U.S. Geological Survey, Cascades Volcano Observatory).

The 1980 eruption of Mount St. Helens dramatically altered the conical profile of the volcano. The eruption left a 2 x 3.5 km wide horseshoe-shaped crater, seen here from the NNE beyond Spirit Lake (center). The landslide of 18 May lowered the summit by 400 m and produced a highly mobile debris avalanche that swept into Spirit Lake and traveled down the North Fork Toutle River. The associated northward-directed lateral blast devastated about 600 km2.

Photo by Lyn Topinka, 1981 (U.S. Geological Survey, Cascades Volcano Observatory).

Keywords: landslide scarp | debris avalanche deposit | crater | lava dome | plume | degassing | deposit | environmental impact


St. Helens