National Geographic : 2009 Aug
0.24 600 240 67 3rd Eruption 8.43 mi 2nd Eruption 1.3 million years ago 640,000 years ago 2.1 million years ago 1st Eruption 1980 Mt. St. Helens Eruption CANADA UNITED STATES MEXICO DETAILED AT LEFT MOUNT ST. HELENS 1980 Gulf of Mexico YELLOWSTONE PLATEAU VOLCANIC FIELD 2.1 million years ago 1.3 million years ago 640,000 years ago ALEJANDRO TUMAS, NG STAFF; SHELLEY SPERRY; NGM MAPS SOURCES: ATLAS OF YELLOWSTONE, UNIVERSITY OF OREGON AND YELLOWSTONE NATIONAL PARK MAIN MAP ; ROBERT L. CHRISTIANSEN AND KENNETH L. PIERCE, USGS How Big? Some events spread ash thousands of miles. After the biggest eruption, wind carried dust around the globe, and ash piled up in drifts across the western half of the U.S. Near the caldera, lava and debris hardened into layers hundreds of feet thick. For years pollutants chilled the climate, devastating ecosystems. Monumental. The combined material from the three events would fill the Grand Canyon. The largest ejected enough rock, lava, and ash to bury an area the size of California under more than 20 feet of debris. Even the smallest was 280 times more voluminous than the 1980 eruption of Mount St. Helens. How Far? Ash Coverage Comparative Volume of Eruptions In cubic miles 0mi 500 0km 500 The Yellowstone Eruptions Three major blasts, bigger than most known prehistoric eruptions, have shaken the Yellowstone National Park area in its two million years atop the plume.