An ABC News story has brought back the caldera scare.
Just 20 miles beneath the earth's surface lies a pressurized ocean of molten rock looking for a way out. And a massive release of that molten rock would create a supervolcano - arguably the largest natural disaster humanity would ever face.
Unlike regular volcanoes, which are shaped like mammoth cones, supervolcanoes spring from massive canyons - calderas - that measure hundreds of miles across. Underneath their surface is a vast lake of lava. When the underground liquid rock - magma - bursts forth to the surface, a series of violent, massive explosions could occur in a wide-ranging eruption that could last several days. It would incinerate anyone within a hundred miles, and layers of ash would blanket much of the earth.
***
The ash cloud would become so thick it could cover the sun, causing global temperatures to plummet.
Scientists say such an event wiped out almost the world's entire population 74,000 years ago, when a supervolcano erupted in Toba, near the Indonesian island of Sumatra. Only a few thousand people survived.
The threat of a caldera exploding or a supervolcanic eruption is very real but it is nothing new. The threat resurfaces every now and then in news articles. With our current technology there is not much we can do to prevent a caldera. Yellowstone National Park contains a caldera which is explained in this article provided by the park's website. A list of other calderas can be found here. The USGS also has a Caldera page.
