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Island Park Caldera

The volcanic feature commonly called the Island Park Caldera in the states of Idaho and Wyoming, U.S., is actually two calderas, one nested inside the other. The Island Park Caldera is the older and much larger caldera, with approximate dimensions of 58 miles (93 km) by 40 miles (64 km). Its ashfall is the source of the Huckleberry Ridge Tuff that is found from southern California to the Mississippi River near St. Louis. This supereruption (2500 cubic kilometers) occurred 2.1 Ma and produced 2,500 times as much ash as the 1980 Mount St. Helens eruption.