When Mount St. Helens erupted on May 18, 1980, the top 400 meters (1,300 feet) of the volcano disappeared within minutes. The blast area covered more than 390 square kilometers (150 square miles) and sent thousands of tons of ash into the upper atmosphere. The collection of still images and video featured in this resource produced for Teachers' Domain depict before-and-after scenes of Mount St. Helens and its surroundings, allowing you to witness the volcano's evolving eruption column, and revealing the extent of environmental recovery 20 years later.
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