A submarine mountain in the northwest Pacific could be the largest single volcano on Earth, rivalling even the mighty Olympic Mons on Mars.

Tamu Massif, situated 1,500 kilometres east of Japan, is roughly the size of the British Isles. Seismic-profiling studies penetrated its depths and revealed that its lava flows dip away from the volcano's summit in all directions. This suggests that all the lava came from a single eruptive vent, say William Sager of the University of Houston in Texas and his colleagues.

The dome-shaped mountain probably formed in a single eruptive blast that began some 140 million years ago.

Nature Geosci. http://doi.org/nqd (2013) Footnote 1