What is a supervolcano?
The term "supervolcano" implies a volcanic center that has had an eruption of magnitude 8 on the Volcano Explosivity Index (VEI), meaning that at one point in time, it erupted more than 1,000 cubic kilometers (240 cubic miles) of material. Eruptions of that size generally create a circular collapse feature called a caldera.
The largest eruption at Yellowstone (2.1 million years ago) had a volume of 2,450 cubic kilometers. Like many other supervolcanoes, Yellowstone has also had much smaller eruptions.
Other volcanoes that produced exceedingly large pyroclastic eruptions and formed large calderas in the past 2 million years include Long Valley in eastern California, Valles Caldera in New Mexico, Toba in Indonesia, and Taupo in New Zealand.
Additional "supervolcanoes" include the large caldera volcanoes of Japan, Indonesia, and South America. The most recent supervolcanic eruption on Earth occurred 26,500 years ago at Taupo located at the center of New Zealand's north island.
Midway Geyser Basin at Sunset, Yellowstone National Park
Dr. Kenneth Pierce studied the geology and geomorphology of the greater Yellowstone area for nearly his entire career with the U.S. Geological Survey. From 1965 to present, Dr. Pierce has mapped glacial deposits, pioneered Quaternary dating techniques, conducted research on the Yellowstone Hot Spot, studied the geothermal areas, explored the geology of archaeological sites...
A caldera is a large, usually circular volcanic depression formed when magma is withdrawn or erupted from a shallow underground magma reservoir. It is often difficult to visualize how calderas form. This simple experiment using flour, a balloon, tubing, and a bicycle pump, provides a helpful visualization for caldera formation.
Giant ash cloud from the eruption of Mount Pinatubo, 1991 towering above farms and agricultural lands in the Philippines.