The loosely defined term "supervolcano '' has been used to describe volcanic fields that produce exceptionally large volcanic eruptions. Thus defined, the Yellowstone Supervolcano is the volcanic field which produced the latest three supereruptions from the Yellowstone hotspot; it also produced one additional smaller eruption, thereby creating the West Thumb of Yellowstone Lake 174,000 years ago. The three supereruptions occurred 2.1 million, 1.3 million, and approximately 630,000 years ago, forming the Island Park Caldera, the Henry 's Fork Caldera, and Yellowstone calderas, respectively. The Island Park Caldera supereruption (2.1 million years ago), which produced the Huckleberry Ridge Tuff, was the largest, and produced 2,500 times as much ash as the 1980 Mount St. Helens eruption. The next biggest supereruption formed the Yellowstone Caldera (~ 630,000 years ago) and produced the Lava Creek Tuff. The Henry 's Fork Caldera (1.2 million years ago) produced the smaller Mesa Falls Tuff, but is the only caldera from the Snake River Plain - Yellowstone hotspot that is plainly visible today.
when was the last time yellowstone supervolcano erupted
174,000 years ago