Tuesday, July 18, 2017

This Map Shows Earth's Turbulent History of Supervolcano Eruptions

[Inverse] A sudden swarm of earthquakes in Montana set off fears that the supervolcano at Yellowstone National Park could be reawakened in early July, spewing more lava by volume than there is ice in the iceberg that just broke off Antarctica’s Larsen C ice shelf.
It was, however, fake news that the Yellowstone supervolcano — or “lava geyser,” as the post called it — was spewing lava. While experts do not expect the Yellowstone volcano to erupt without warning, there’s always a small probability. According to one scientific study, there’s a one percent chance of a supereruption in the next 7,200 years.
A supervolcano is typically defined as a volcano that ejects at least 240 cubic miles of magma in one eruption to earn a Magnitude 8 or higher on the Volcanic Explosivity Index. To put that in perspective, the 1980 eruption of Mount St. Helen’s expelled just 0.7 cubic miles of rock.
Supervolcanoes don’t form mountain peaks, but instead form massive craters called calderas. As the magma chamber under the surface shoots massive quantities of gas, ash, and molten rock upwards through seams in Earth’s crust, the ground sinks down to fill the emptying cavity below.
This map, though incomplete, shows some of the past major volcanic events of Earth’s relatively recent history, on the order of dozens of millions of years. Evidence of much older events will have been washed away by the dynamic ticking of geological time. Magnitude 8 supervolcano eruptions are in red. The smaller orange icons show the larger Magnitude 7 events of the past. See Maps and Read More