Tamu Massif, which rises from the floor of the Pacific Ocean east of Japan to cover an astonishing 260,000 sq km, is no longer the world’s largest volcano.
Why? Simply put, new scientific evidence reported in Nature Geoscience states that it’s not actually a volcano. This means that Mauna Loa, one of five volcanoes that form the island of Hawaii, is now top of the rankings, again. It was dethroned in 2013 when earlier research on the Tamu Massif suggested it was a shield volcano.
You’d think that there would be some controversy between the authors of the conflicting studies, but no. Both were actually penned by the same marine geophysicist, William Sager. Working for the University of Houston, he has been studying Tamu Massif for almost three decades and his differing conclusions are simply based on the best information he had available to him at the time. His earlier work, which used drill results, revealed thick lava flows from a single point of origin within the massif, while the most recent study used detailed examinations of magnetic signatures across the huge rock mass. The patterns revealed in the latter strongly suggest that the Tamu Massif is in fact oceanic crust. But not just any oceanic crust, rather an unparalleled pile of it that reaches an incredible thickness of 32km – four times the global average. This fact still makes it incredibly fascinating, and will undoubtedly lead to further scientific studies.
Unlike the Tamu Massif, Mauna Loa breaks the surface of the Pacific and is possible to visit while on the island of Hawaii – its summit is part of Hawaii Volcanoes National Park.
While the Mauna Loa’s maximum elevation is 4169m, its height above the seafloor is an incredible 9170m, which means that if it started at sea level it would surpass even Mount Everest. Eruptions on Mauna Loa date back some 700,000 years, with the last fireworks taking place in 1984.