Researchers have announced the discovery of two newly-identified super-eruptions associated with the Yellowstone hotspot, including what they believe was the volcanic province’s largest and most cataclysmic event. The results suggest the holiday hotspot, which today fuels the famous geysers, mudpots, and fumaroles in Yellowstone National Park, may be waning in intensity.
Dr Thomas Knott, a volcanologist at the University of Leicester and the paper’s lead author, said: “We discovered that deposits previously believed to belong to multiple, smaller eruptions were, in fact, colossal sheets of volcanic material from two previously unknown super-eruptions at about 9.0 and 8.7 million years ago.
“The younger of the two, the Grey’s Landing super-eruption, is now the largest recorded event of the entire Snake-River–Yellowstone volcanic province.”
Based on the most recent collations of super-eruption sizes, he added, “It is one of the top five eruptions of all time.”
The team, which also includes researchers from the British Geological Survey and the University of California, estimates the Grey’s Landing super-eruption was 30 percent larger than the previous record-holder, the Huckleberry Ridge Tuff.
The volcanic eruption had devastating local and global effects.
Dr Knott said: “The Grey’s Landing eruption enameled an area the size of New Jersey in searing-hot volcanic glass that instantly sterilised the land surface.
“Anything located within this region, he says, would have been buried and most likely vaporised during the eruption.
“Particulates would have choked the stratosphere, raining fine ash over the entire United States and gradually encompassing the globe.”
Dr Knott said: “It, therefore, seems that the Yellowstone hotspot has experienced a three-fold decrease in its capacity to produce super-eruption events. This is a very significant decline.”
However, these findings, have little impact on assessing the risk of another super-eruption occurring in Yellowstone now.
Dr Knott said: “We have demonstrated that the recurrence rate of Yellowstone super-eruptions appears to be once every 1.5 million years.
“The last super-eruption there was 630,000 years ago, suggesting we may have up to 900,000 years before another eruption of this scale occurs.”
But this is a highly inexact estimate, with the volcanologist stressing continuous monitoring must continue in the Yellowstone region, which is being conducted by the US Geological Survey (USGS).
He said this “is a must” and that warnings of any uptick in activity would be issued well in advance.