Lobby > Exhibits > Why Geysers Erupt > Underlying Geology > Volcano Comparisons

The three caldera-forming eruptions at Yellowstone (2.1 million years ago, 1.3 million years ago, and 640,000 years ago), were respectively about 2,500, 700, and 1,000 times larger than the 1980 eruption of Mt. St. Helens in the state of Washington.

Mount Mazama, a former stratovolcano, is more famous for what formed in the aftermath of its catastrophic eruption some 7,000 years ago. Where a 12,000-foot volcanic cone once stood, now lies Crater Lake, the main feature of Crater Lake National Park located in southern Oregon.

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