The Tamu Massif, part of the Shatsky Rise oceanic plateau in the northwestern Pacific Ocean, could be one giant volcano, reports a study published online this week in Nature Geoscience. If so, the volcano may be the largest known on Earth.

William Sager and colleagues use seismic data and rock samples drilled from the northwestern Pacific Ocean sea bed to image and analyse the structure of the Tamu Massif, which formed about 145 million years ago. They found that it is probably one large volcano, about the size of the British Isles. If so, it is comparable in size to the Olympus Mons Volcano on Mars and could be one of the biggest volcanoes in the Solar System.