The Largest Volcano on Earth Is Under the Ocean

The ocean is full of surprises. It's already well known as the stomping grounds of massive squids and creepy sharks, but today, we can add another bullet point to the list of sea secrets. According to a new report in Nature Geoscience, the largest volcano on planet Earth resides under the Northwestern Pacific Ocean.

The volcano in question is called Tamu Massif, named after Texas A&M University, where lead researcher William Sager used to work. Tamu is one-third of a large underwater plateau that formed when three tectonic plates detached from each other in the Late Jurassic or Early Cretaceous period. It has been inactive for about 140 million years, but according to the report, its explosive potential or even lack thereof isn't what interests scientists.

Mainly, all the fuss is about its size. Tamu's area of 3.1 x 105 square kilometers is just about the same as that of the entirety of the British Isles. This revelation knocks Mauna Loa, one of the volcanic mountains that comprise Hawaii, out of the top position for the largest volcano on Earth.

The size of Tamu also rivals that of Olympus Mons on Mars, which has held the distinction of being the largest known volcano in the solar system since it was discovered in the early seventies by NASA’s Mariner 9 space orbiter. Olympus Mons may be taller, reaching around 22 km or 14 miles into the Martian sky, but it is only 25 percent larger than Tamu in terms of volume.

Also of note, Tamu is a single structure rather than a smattering of smaller volcanoes. The researchers note that larger “volcanic complexes” do exist, but the sheer size of this one, standalone monstrosity is impressive.

So the big question is: Why did it take us so long to fully measure this behemoth? Tamu Massif’s underwater location is to blame. Hidden in the depths, the volcano is shrouded, which poses significant obstacles for geoscientists that try to study it. For this particular exploration of Tamu, a combination of “multichannel seismic profiles and rock samples” held the key to better understanding the volcano.

The researchers noted in a chat with Nature.com that there are probably other equally or more massive volcanoes hiding underwater like Tamu. My own personal speculation is there might even be one actually larger than Olympus Mons. So, Mars: We are coming for you.