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).