Yellowstone National Park, renowned for its scenic vistas, abundant wildlife and geothermal wonders, is a relatively recent addition to the American landscape. Formed by a massive volcanic explosion 2 million years ago (at the onset of the Pleistocene Ice Age) and by subsequent eruptions 1.2 million and 600,000 years ago, the Park's magnificent topography stretches across the broad, remnant caldera of those volcanic blasts. When will the next eruption occur? A look at the spacing of previous eruptions is certainly unsettling.
Yellowstone's geysers and hot springs attest to the continued presence of a "hot spot," a mantle plume close enough to the surface to generate these hydrothermal features. And recent Park surveys have confirmed a gradual bulging of the region's crust. Whether the risk of a major eruption has been reduced by previous volcanism and by subsequent movement of the North American Plate remains uncertain.
Like the San Andreas Fault and the Cascade Volcanoes, Yellowstone is a potential natural catastrophe that will eventually occur. Our brief life spans shelter us from the long view of geologic history and tend to make us oblivious to the risks inherent in our planet's ongoing evolution. The explosion of the Toba Volcano, in Sumatra, 74,000 years ago, nearly wiped out the human species; a fourth eruption of Yellowstone could be just as disastrous!
