Far off the coast of Japan, and deep below the Pacific Ocean’s surface, lies the world’s largest volcano. Roughly the size of Arkansas, it was recently discovered by a team of scientists from the University of Houston.
The volcano is named Tamu Massif, after Texas A&M University (TAMU), where lead researcher William Sager used to work. Its peak is about a mile below the ocean’s surface, and its base on the ocean floor is four miles from the surface. It’s about 60 times the size of the largest active volcano on land, Mauna Loa in Hawaii. Fortunately, Tamu Massif hasn’t been active for 145 million years.
A SEISMIC FIND
Sager found the volcano while studying the formation of one of the world’s biggest underwater plateaus, which are high, flat areas of land. Since it’s hard to see deep under the water’s surface, his team used sound technology called seismic reflection to create a computer-generated picture of the mountainous region.
Scientists created a loud noise, “like a pop,” says Sager. That sound wave traveled through the water, bounced off the ocean floor, and came back up. The sound waves bounced back at different lengths, depending on the depth of the underwater landforms they hit.
Recording equipment on the ship made a picture based on the length of the sound waves. These images revealed Tamu Massif—a single, massive, underwater volcano.
Tamu Massif isn’t as steep as other volcanoes. When Tamu Massif erupted, “pillows of lava” up to 75 feet thick flowed through the water for hundreds of miles along the ocean floor, says Sager.
This lava cooled, adding to the volcano’s structure. Because the lava spewed so far from the crater of the volcano (the hole at the top, from which lava flows), the sides are much more level than those of volcanoes like Mauna Loa.
Sager and his team carried out their research over a few expeditions, some lasting as long as eight weeks. “It really is in the middle of nowhere,” Sager says of Tamu Massif, which is about 1,000 miles from Japan.
“We didn’t set out to find the biggest volcano in the world,” says Sager. “But that was a happy result.”