Landsat satellite data, archived by the U.S. Geological Survey, have proven useful for studying land surface changes over time. Images of the Mount St. Helens region in southwestern Washington illustrate the conditions before, shortly after, and decades after the eruptions of the Mount St. Helens volcano in 1980. That eruption was the most economically destructive eruption in United States history.
The 1974 image shows the snow on the southern slopes and the heavy forests surrounding the volcano.
In the spring of 1980, a series of eruptions, climaxed by a May 18 massive eruption, destroyed river channels, homes, and heavy forests. The 1980 Landsat image, acquired months after the May eruption, shows the resulting flow of lava and ash.
By 2011, much of the region had recovered. Forests and grasslands have regrown and the lakes and rivers have been recharged. A small section on the northern slope of the volcano is still dominated by ash, preventing extensive vegetation growth.