Discovery of ancient super-eruptions indicates the Yellowstone hotspot may be waning

two previously unknown super-eruptions at about 9.0 and 8.7 million years ago
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"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," says Knott. Based on the most recent collations of super-eruption sizes, he adds, "It is one of the top five eruptions of all time."
Also, the hotspot used to go off every 500,000 years or so, but now it's up to once every 1.5 million years.