The 1980 eruption of Mount St. Helens, a stratovolcano located in Washington state, in the United States, was a major volcanic eruption. The eruption, which was a (VEI = 5) event, was the only significant one to occur in the contiguous 48 U.S. states since the 1915 eruption of California's Lassen Peak.
The eruption was preceded by a two-month series of earthquakes and...
