On May 18, 1980, Mount St. Helens erupted and its northern flank collapsed, leading to the largest landslide in U.S. history. Volcanic debris from the explosion, collapse of the flank, and subsequent lahars spread out over roughly 230 square miles. The eruption sent debris flying out in winds that reached up to 250 miles per hour at temperatures of 680 degrees Fahrenheit. Ash, rock, water, snow, ice, steam, and downed trees meshed into a slurry and scoured the landscape and dammed up rivers. Fifty seven people died. In the 32 years since, the forest has begun to grow back and rivers have carved new paths through the terrain. You can see a bird's eye view of the recovery thanks to a new video and pictures series from the Landsat program.
Mount St. Helen's, 1979. Photo: Landsat
Landsat is a government program run by NASA and the USGS that uses satellite imagery from space to chronicle changes to the earth from man and natural processes. The 40-year-old program recently released a series showing the 10 most significant images it has ever captured. The galleries show the shrinking of the Aral Sea, the expansion of Las Vegas, the deforestation of tropical rainforests, the effect of the oil fires in Kuwait, and the recovery of the land around Mount St. Helens.
Mount St. Helen's, September, 1980. Photo: Landsat
The red color in the early images of Mount St. Helen's represent vegetation. (Old satellites couldn't detect blue light, which was needed to make an accurate color photograph. In later years, the images changed to a more recognizable green.) In the 2011 photo below, the area that is still grey is called the Pumice Plains. NASA's Earth Observatory reported this past spring that there are signs of life here as well. The first vegetation to appear was a prairie lupine, a small flowering plant that can take nitrogen from the air instead of the soil.
Mount St. Helen's, 2011. Photo: Landsat