Thirty Year Anniversary of Mount St. Helens Eruption

May 18, 2010

20100518 – Tuesday - Thirty Year Anniversary of Mount St. Helens Eruption 

20100518 – Tuesday - Thirty Year Anniversary of Mount St. Helens Eruption 2

Photos from VolcanoCam on Mount St. Helens (USDA Forest Service) and from the USGS (Harry Glicken)
Summary Author: USDA Forest Service; Jim Foster

The photo above at top showing a still snow-covered Mount St. Helens was taken yesterday from a live VolcanoCam on Johnson’s Ridge Observatory, Washington. The Observatory and VolcanoCam are located at an elevation of approximately 4,500 ft (1,372 m), about five miles (eight km) from the volcano. You’re looking toward the south-southeast across the North Fork Toutle River Valley. An innocent looking Mount St. Helens on May 17, 1980 is shown at bottom.
 
Thirty years ago today, Mount St. Helens erupted with a titanic sideways blast, reducing its elevation from 9,677 ft (2,950 m) to 8,365 ft (2,550 m). The eruption damage, plus the massive avalanches and mudflows generated by the near-instantaneous melting of deep snow packs on the flanks of Mount St. Helens, completely devastated approximately 232 sq. mi (600 sq. km) of the mountain and its environs. Prior to the eruption of Mount St. Helens, the largest most recent eruption in the contiguous U.S. occurred at Lassen Peak in May of 1922.