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Mon August 6, 2012
Dr. Ben Ellis, Washington State University – Yellowstone Super Volcano
In today’s Academic Minute, Dr. Ben Ellis of Washington State University reveals research indicating that the Yellowstone super volcano may have erupted more frequently than previously thought.
Ben Ellis is a post-doctoral researcher in the School of the Environment at Washington State University where his research interests include constraining the volume and frequency of explosive eruptions from silicic volcanoes. He holds a Ph.D in Geology from the University of Leicester.
Dr. Ben Ellis – Yellowstone Super Volcano
Yellowstone is globally famous as a ‘super-volcano’. For the past twenty years it has been generally accepted that the largest eruption from the Yellowstone volcano was that of the Huckleberry Ridge Tuff (HRT) approximately 2 million years ago which produced ~2,500 km3 of deposit.
It has been known since the 1970’s that the HRT was composed of three distinct members; A (lowest), B (middle), and C (top), based on differences in the proportions and sizes of crystals in each member. Moreover, isotopic compositions of the members (a way of tracing how the magma was made) were starkly different. If the HRT represented the product of a single eruption not only would it be the most isotopically diverse magma ever erupted on Earth, it would be three times more diverse than the runner-up. This got us thinking.
Despite the large number of studies of the Yellowstone volcano nobody had tested the hypothesis that the HRT did indeed represent a single event. Our study used high-precision geochronology from single crystals within each of the members of the HRT to derive ages for the individual members. As a result of painstaking work in the laboratory by co-author Dr. Darren Mark our study shows that member C erupted at least 6,000 years later than members A and B.
Alone, member C of the HRT represents a large eruption, being some three hundred times larger than the 1980 Mt. St. Helens event, while members A and B together represent the fourth largest eruption known. Our results indicate that large, explosive eruptions from the Yellowstone volcano are more frequent than previously thought. More broadly our study illustrates that large volcanic deposits may represent numerous closely spaced events rather than a single eruption. We wonder if in years to come whether ‘super-eruptions’ will still be so super?