India, March 21 -- Obviously, many visitors to Yellowstone National Park gape in awe at the roaming bison or the colour of the Grand Prismatic Spring, but few know that the park is standing over a giant supervolcano.

Volcanoes are known to have existed or may exist in regions where colossal volcanic eruptions, with at least 1,000 cubic kilometres of volcanic material being ejected, occurred. The Yellowstone Plateau Volcanic Field covers most of Yellowstone National Park and extends across parts of Wyoming, Montana, and Idaho.

"While driving south from Mammoth Hot Springs towards Norris Geyser Basin early on Aug. 5 last summer, a park scientist noticed a billowing steam column through the trees and across a marshy expanse," Yellowstone N...