Volcanoes could be a greater threat to civilization than previously thought.
The largest supervolcano in the world is located in Wyoming's Yellowstone National Park and measures 53 miles wide.
Although the Caldera is now dormant, in the past it produced three of the world's most monstrous eruptions.
If it erupted today, anyone within dozens of miles would be annihilated. Ash clouds would spread across the United States, blocking sunlight and pushing temperatures down by 9 to 15 degrees for years.
"Such events could result in the ruin of world agriculture, severe disruption of food supplies, and mass starvation. The effects could be sufficiently severe to threaten the fabric of civilization," a report from the Geological Society of London said.
It could also lead to as much as a billion casualties.