Mount St. Helens erupted on May 18, 1980 and it is widely considered the most disastrous volcanic eruption in U.S. history. It killed 57 people and destroyed hundreds of homes, 57 bridges and some 200 miles of roads, in addition to leveling tens of thousands of acres of forest.
The eruption sent an ash cloud more than 12 miles into the atmosphere in just 10 minutes. Fine ash reached the Northeast two days later and circled the earth within 15 days, according to the U.S. Geological Survey. The volcano had been dormant for more than 100 years until seismic activity started to increase in March 1980.
