A volcano the size of Arizona has been discovered in the Pacific Ocean. USA Today reported that the discovery is located about 1000 miles east of Japan and is the earth's largest volcano.

The volcano is called Tamu Massif and is 280 miles by 400 miles. Geologists believe that it is made of several volcanoes that merged together.

"We saw what appear to be lava flows going out from the center of the volcano in all directions, with no obvious large secondary source of volcanism," says lead author of the University of Houston's study, William Sager to USA Today.

Previously the world's largest volcano was Mauna Loa, which is one of five that form the Big Island of Hawaii.

The volcano rivals Olympus Mons which is the largest volcano in the solar system, located on Mars.

 "Olympus Mons is the 800-pound gorilla of the solar system," said Sager to The Washington Post. "We didn't know these massive volcanoes were here on Earth."

"Tamu Massif formed layer by layer as fast-moving lava flowed from a central area at the peak and ran down its flank, cooling in place. The volcano is completely submerged, and Sager doesn't believe that its peak ever rose above sea level over its 145-million-year lifetime," reported The Washington Post.

The team says there's no danger of an eruption. Clive R. Neal, a volcanologist at the University of Notre Dame said to The Washington Post, "That's probably a good thing, since we've been able to correlate mass extinction with some of these beasts."

 "This finding is paving the way to really rewriting some of the textbooks," he added. "The term 'supervolcano' might be a reality."

The study was published online on Thursday in the journal of Nature Geoscience.

"Sager and his colleagues first studied Tamu Massif on a research cruise almost 20 years ago without knowing it was a single volcano. At the time, they were gathering data on a larger undersea mountain range called Shatsky Rise, which contains the giant within its features," reported The Washington Post.