Tamu Massif: The Most Massive Volcano
Most of the world's largest features are so clearly visible that they have been known and recognized for hundreds of years. One exception is Tamu Massif. It is now recognized to be a single volcano - instead of a volcano complex with multiple vents. Tamu Massif has a footprint that covers more area than any other volcano - about 120, 000 square miles (310, 800 square kilometers) - an area about the size of New Mexico. It also has a larger mass than any other known single volcano on Earth. How could this enormous volcano have escaped recognition until 2013?
Three things helped Tamu Massif escape recognition as the world's most massive volcano and the volcano with the largest footprint:
1) Remote Location: Tamu Massif is located in a remote part of the northwestern Pacific Ocean about 1000 miles (1609 kilometers) east of Japan. Its summit is over 6500 feet (2000 meters) below sea level. This remote location and great depth made it very difficult to collect information about the volcano. For decades, researchers knew more about the large volcanoes on Mars than they knew about Tamu Massif.
2) Not an Obvious Mountain: Most volcanoes are an obvious "mountain, " but the slopes of Tamu Massif are very gentle. Just below the summit, the slope of the volcano is less than one degree. Near the base of the volcano, the slope is less than one-half degree. It is not a volcano that abruptly and steeply climbs skyward from the seafloor.
3) Tamu Massif Fooled Scientists: They knew that Tamu Massif was a volcanic mountain; however, they assumed that it was a volcanic complex made up of multiple volcanoes that had merged together. It was not until seismic data revealed that its many lava flows emerged from a single vent and geochemical analysis revealed that the lava flows had similar compositions and were approximately the same age.
Tamu Massif is the largest volcano on Earth - unless an even larger volcano remains to be discovered on the deep ocean floor.
Seafloor 3-D image shows size and shape of Tamu Massif, Earth's largest single volcano. Image by Will Sager, National Science Foundation.