Earth has some impressive displays of natural force, such as hurricanes, earthquakes, tsunamis, and volcanoes. But under this world’s deceptively tranquil surface lies a destructive power Earth has yet to show: the supervolcano. One of the most recent supervolcanic eruptions at Lake Toba about 74,000 years ago may have nearly caused the extinction of the human race.
Just So Super
A volcano is classified as “super” when its eruption registers on a magnitude of 8, the highest level on the Volcano Explosivity Index (VEI). The U.S. Geological Survey defines a supervolcano as “a volcano that at one point in time erupted more than 1,000 cubic kilometers of deposits.” To put this into perspective, this would make the supervolcano over 1,000 times more explosive than the Mt. St. Helens eruption in 1980.
The potential destructive power packed into a supervolcano gives new meaning to the word catastrophic. Not only would a supervolcano cause massive destruction in the hundreds of miles around it, but the amount of ash, debris, and gas thrown into the atmosphere would cause a global climate change that might last years, even decades.
A few supervolcanoes are still active today. One of the largest is Yellowstone, in Wyoming. Other areas in the U.S. thought to be supervolcanoes are Long Valley in California, Valles Calderas in New Mexico, and La Garita Caldera in Colorado. An eruption about 74,000 years ago, in what is now Lake Toba in Indonesia, created a global climate change that may have been responsible for a population bottleneck in humans, a near extinction event. Aira Caldera in Japan and Taupo Volcano in New Zealand are among a few other supervolcanic areas in the world.
All volcanic activity is closely watched by volcanologists around the world. So far, none of these supervolcanoes have given signs of imminent eruption, such as earthquake swarms or rapid changes in topography. Like all forces of nature, a mega eruption can’t be predicted, but scientists are confident that there would be signs, possibly years in advance of an explosion. Supervolcanoes like the one in Yellowstone might be ticking time bombs, but apparently they have slow timers.
1. U. S. Geological Survey: “Questions About Supervolcanoes”