yellowstone supervolcano Is the Yellowstone Supervolcano Ready to Erupt? Over the past two million years, the Yellowstone supervolcano has erupted every 600,000 years. It was 640,000 years ago when it last exploded. Another eruption, geologically speaking, is therefore, threatening. Five miles beneath Yellowstone, lies an immense pool of red hot magma. Fed from the Earth's mantle, it has been growing. This reservoir of magma and gas is now 31 miles long, 19 miles wide, and six miles deep. The building pressures must be enormous. The Yellowstone "hot spot" is considered the foundation of a rare "supervolcano." It is estimated that a supervolcano would erupt with the power at least 1000 times greater than that of an 'ordinary' volcano. The eruption 640,000 years ago created an extremely large crater - the caldera - that today comprises a major portion of the center of the park. Signs of increased volcanic activity have recently been observed in and around Yellowstone National Park. The north part of Yellowstone Lake has bulged by nearly 170 feet over the past 50 years. The lake has spread into forest on one side of the lake as the surface beneath the water has inflated. A massive eruption of the Yelowstone supervolcano would be catastophic for North America and would also result in years of freezing temperatures for the rest of the planet as volcanic dust and ash obscured the warmth of the sun.