Supervolcanos formed by massive explosions have erupted several times. The Yellowstone hotspot, as the caldera in Wyoming is sometimes called, last erupted about 640,000 years ago. But other eruptions have been recorded in modern history. In 1815, Mount Tambora in Indonesia erupted causing what came to be called “The Year Without a Summer” because the amount of ash that spewed into the atmosphere blocked the sun’s rays.
Scientists from the University of Utah and the United States Geological Survey monitor the volcano in a joint project called the Yellowstone Volcano Observatory. Supereruptions are classified as those that produce more than one thousand cubic kilometers of ash. In 2014, the USGS completed a study modeling the effects of a potential eruption. The study predicts that in the event of an eruption, volcanic ash would spread across most of the United States with some areas being covered in up to a meter of ash.
Supervolcanos are volcanos which eject more than a thousand cubic kilometers of what volcanologists call “ejecta,” ash, rock, and magma spewed from a volcano during an eruption. That’s more than 264 trillion gallons of material. On the Volcanic Explosivity Index, supervolcanos measure in the 7, 8 or higher. The 1980 eruption of Mt. St. Helens in Washington measured 5 on the VEI.