There’s been a so-called “super eruption” every approximate 650,000 years. The last one was about, ‘gulp’, 650,000 years ago.
What month?
Hi Frantzie! You asked about the size of the volcano.
Well, Yellowstone is a super volcano, and the size of the caldera’s perimeter is approximately the size of the whole of Yellowstone Park. Yes, it is huge and it is dangerous.
See post #39 for a really good idea of what Yellowstone is volcanically: it is much like Hawaii, in that it is a ‘hot spot’ in the earth’s mantle with a tectonic plate sliding over it through geologic time. The geology tells the story of past eruptions.