Beneath Yellowstone National Park lies a supervolcano that can become primed for an eruption in decades rather than the millennia that was previously thought. The odds of an eruption are very small, but scientists have discovered that conditions that lead to super eruptions can emerge within the typical life span of a human. A full-blown eruption of the Yellowstone supervolcano would have up to 2000 times the power of the Mount St. Helens eruption of 1980 and would likely cover the US in a thick layer of ash and send the Earth into a volcanic winter.
A supervolcano eruption can spew out hundreds of cubic miles of magma, but, fortunately, such eruptions are rare. [Note- the term "supervolcano" was first used in a TV documentary to describe eruptions of more than 1,000 cubic kilometers of magma]. There are 20 supervolcanoes around Earth and the last super-eruption happened in Sumatra, Indonesia about 74,000 years ago. Geologic evidence suggests that Yellowstone’s supervolcano usually erupts every 600,000 to 800,000 years and the most recent occurred about 631,000 years ago.
Up until this recent finding, it was generally assumed by scientists that when Yellowstone’s supervolcano began to rumble and its magma chambers began to fill, we would have centuries to “prepare” for the devastating eruption. However, recent findings suggest that the speed at which the volcano can fill its magma chamber and erupt is on the order of a few decades. In other words, the Yellowstone supervolcano can go from its usual activity like today to a massive eruption in the 2030’s.
To reach the conclusion in this study, Arizona State University scientists spent weeks at Yellowstone’s Lava Creek Tuff – a fossilized ash deposit from its last super eruption – and collected many samples of rocks. As magma chambers fill in the time leading up to an eruption, portions of the magma become cool enough to solidify into rock. While they solidify, the minerals grow over time and create bands of progressively younger mineral around older mineral. In this study, scientists inspected the mineral bands around Yellowstone and found that the last few bands recorded a sudden spike in temperature on the order of decades before the mineral lithification process came to an end. The rapid increase in temperatures on the order of decades represents the time required for a sudden injection of magma and release through an eruption (source).
The famed Yellowstone volcano has become of increased interest in recent months; especially, over the summer when more than 400 earthquakes hit the area in just one week. While this was the highest number of earthquakes at Yellowstone within a single week in the past five years, earthquake swarms are nothing new and this was actually fewer than weekly counts during 2002, 2004, 2008 and 2010. Experts at the U.S. Geological Survey (USGS) say the risk of the Yellowstone supervolcano erupting is quite low, with a probability of one in 730,000.
Meteorologist Paul Dorian