-- [full size image, 55k] -- Listed below are two places in the United States that are considered "active" volcanic areas.
On May 18, 1980, after a long period of rest, this quiet mountain in Washington provided detailed observations on the mechanics of highly explosive eruptions.
This field seismometer measures earthquakes associated with subsurface volcanic forces and may help to predict future events. It sits on a plateau known as the "Volcanic Tableland" formed by a major eruption 600,000 years ago.