What is Mt. St. Helens?
Wikipedia defines it as:
Mount St. Helens is an active stratovolcano located in Skamania County, Washington, in the Pacific Northwest region of the United States. It is 96 miles south of Seattle, Washington, and 50 miles northeast of Portland, Oregon.
Or, for a more detailed version: you can read the full article on wikipedia here.
[Image of after the eruption, but with the old summit drawn in. Crazy, huh?]
[After main eruption, minor eruption.]
[Picture 1: During eruption]
[Picture 2: Before eruption]
Video of Eruption:
[This is a video showing the eruption in slow motion.]