The World's Largest Volcano
September 9, 2013 – A massive volcano the size of New Mexico has been identified at the bottom of the Pacific Ocean. It is so big that it is the largest volcano on Earth and is one of the largest volcanoes in our entire solar system!
The volcano, named Tamu Massif, lies 1,600 kilometres (1,000 miles) east of Japan. It is about the same height as Hawaii's Mauna Loa, the previous record holder, but is much wider with a total width of 193,000 square kilometres (120,000 square miles)!
It's also slightly bigger than Olympus Mons on Mars, which was the biggest volcano in our solar system until now!
During the early Cretaceous period 145 million years ago Tamu erupted continuously for a few million years. It has not had any volcanic activity since then.
William Sager, a geology professor at the University of Houston in Texas, started studying Tamu after he discovered it 20 years ago.
Until now Tamu was thought to be three separate things but "We got tired of referring to them as the one on the left, the one on the right and the big one," said Sager. "We knew it was big, but we had no idea it was one large volcano.”
Until now geologists thought Tamu was an oceanic plateau in the northwest Pacific Ocean called the Shatsky Rise. Scientists have known about the Shatsky Rise since the early 1900's but they had no concrete idea how it formed or what it was made of.
Oceanic plateaus are big, wide underwater piles of lava on the ocean floor that either punched through the earth's crust, or more gently seeped through cracks and weeks areas in the crust. Weak areas in the crust are usually at the end of a tectonic plate.
The Shatsky Rise formed where three plates pulled apart and, until now, scientists' best guess as to how it formed was that it was made up of three volcanoes that grew together. After looking at Tamu's seismic data and analyzing core samples that found that the entire structure was made out of the same rock that is all the same age, meaning it is actually one massive volcano.
Unlike most volcanoes it is much wider than it is tall, which is why scientists and geologists have been confused about what exactly it is for so many years.
"If you were standing on its side, you would have trouble telling which way is downhill," explained Sager; this is because the summit the slope is half a degree and it is even less near the base. To put that into perspective, a staircase has a slope of 40 degrees and a beginner's ski hill has a slope of about 10 degrees.
Tamu's shape is "different from any other [underwater] volcano found on Earth, and it's very possible it can give us some clues about how massive volcanoes can form," according to Sager.