The largest single volcano ever found on Earth lies quietly in the depths of the Pacific Ocean, about 1,500 km east of Japan, having been extinct for millions of years. Scientists have now discovered the dome-shaped behemoth, which has a footprint the size of New Mexico.

The discovery topples the previous world record holder for largest volcano — Mauna Loa, one of the five that form the Big Island of Hawaii. The area covered by the newly discovered volcano rivals the biggest volcano in the solar system, Olympus Mons on Mars.

"Olympus Mons is the 800-pound gorilla of the solar system," said geophysicist William W. Sager of the University of Houston, the study's lead author. "We didn't know these massive volcanoes were here on Earth."