Mount St. Helens Comes Alive -- With Plants


Mount St. Helens has come a long way since its historic eruption on May 18, 1980. The above images show two satellite views: one from 1984, when the barest beginnings of green can be seen in some areas; to August 2013, nearly three decades of growth later. These images are featured this week in NASA’s Earth Observatory, where you can explore much higher resolution versions.

The greener image is from August 20, 2013, as seen by the Operational Land Imager (OLI) on the Landsat 8 satellite. The bleaker image is from four years after the eruption, on June 17, 1984, as seen by the Thematic Mapper on Landsat 5. There are earlier images, but not in natural colors.

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It may not be remembered by younger folks, but after this volcano blasted itself in half, the devastated land around it was immediately the source of intense study to see how life would return. It became a giant laboratory for learning how life colonizes and retakes a landscape. Spiders were well represented in the recolonization; between 1981 and 1986, collectors found 14,325 specimens of 125 species in their collection traps across the pumice fields — accounting for 23 percent of the arthropods that took over the top of the volcano first. Spiders are marvelous travelers, floating on silk threads all over the world.

Another factoid that’s often overlooked in all the Mount St. Helens fanfare is that this was a rather small eruption on the global scale of things. But because it was the first such event in modern times in the continental United States, it was studied very closely by geoscientists and provided lessons that were later used to save tens of thousands of lives when the far larger eruption of Mount Pinatubo was preparing to explode in the Philippines in 1991.

IMAGES: NASA Earth Observatory images by Jesse Allen and Robert Simmon, using Landsat 8 data from the USGS Earth Explorer.

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