Tamu Massif is a seamount in the northwest Pacific Ocean,[3] sitting atop a triple junction of mid-ocean ridges.

William Sager, a marine geophysicist from the Department of Earth and Atmospheric Sciences at the University of Houston, began studying Tamu Massif around 1993 at the Texas A&M College of Geosciences.

[1] Tamu Massif was formed during a single geologically brief eruptive period, which scientists had previously thought was impossible on Earth.

Geologic data also indicated that Tamu Massif formed at the junction of three mid-ocean ridges, which was a highly unusual occurrence.

[14] A study found that the Moho line, the boundary between the Earth's crust and mantle, extends more than 30 kilometres (19 mi) beneath the base of Tamu Massif, meaning that the volcano is unlikely to ever erupt again, since magma is presumably unable to penetrate a barrier that thick.