| Mount St Helens | Long Valley | |
| 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. The towering pine trees of this once-quiet mountain were toppled over like toothpicks. | 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. |
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| San Francisco Peaks | MacDougal Crater | |
| Scientists believe that the volcanic eruptions several million years ago that shaped this mountain in northern Arizona were very similar to the ones onserved at Mount St. Helens. | When hot volcanic magma encounters ground water, these explosive eruptions can form deep craters seen just south of Arizona in the Pincate Volcanic region of Mexico. | |
