Tamu Massif is an extinct submarine shield volcano in the northwest Pacific Ocean, with the characteristics of a hybrid between a mid-ocean ridge and a shield volcano. On 5 September 2013, researchers announced that it could be a single volcano which, if corroborated, would make Tamu Massif the largest known volcano on Earth. Tamu Massif is located in the Shatsky Rise about east of Japan. The volcano, which comprises the entire Shatsky Rise, covers an area of about. Its summit is about below the surface of the ocean, and its base extends to about deep. The volcano is about tall. William Sager, a marine geophysicist from the Department of Earth and Atmospheric Sciences at the University of Houston, began studying the volcano in about 1993 at the Texas A&M College of Geosciences. According to Sager and his team, Tamu Massif is "the biggest single shield volcano ever discovered on Earth". Other igneous features on the planet are larger, such as the Ontong Java Plateau, but it has not yet been determined if they are indeed just one volcano or rather complexes of several volcanoes.
Name
The name Tamu is taken from the initials of Texas A&M University, where William Sager, a geology professor at the University of Houston and one of the lead scientists studying the volcano, previously taught. Massif, which means "massive" in French, is a large mountain or a section of the planet's crust that is demarcated by faults and flexures.
Geology
The Tamu Massif was formed about 145 million years ago during the Late Jurassic to Early Cretaceous period over a relatively short period of time and then became extinct. Tamu Massif was formed during one, geologically brief eruptive period, which scientists had previously thought was impossible on Earth. If confirmed, the suggestion that it could be a single volcano would make the Tamu Massif the largest known volcano on Earth, dwarfing the current record-holder, Pūhāhonu, in the Hawaiian Islands. The main part of Tamu's rounded dome extends over an area of, totaling more than, many times larger than Mauna Loa, which has an area of, and about half the area of the Martian volcano Olympus Mons. The entire mass of Tamu consists of basalt. Its slopes are very gradual, ranging from less than half a degree to one degree near its summit. The Shatsky Rise oceanic plateau is comparable in size to California or Japan, but Tamu Massif, which is the plateau's oldest and largest edifice, is comparable in size to New Mexico or Britain and Ireland together. A study in 2016 found that Tamu Massif likely encompassed the entire Shatsky Rise, meaning that Tamu Massif has an area of about, comparable to the size of New Mexico or Japan, and surpassing Olympus Mons in surface area, though it has not yet been determined which of the two volcanoes has a greater mass. Using magnetic lineations, researchers discovered that there are three bathymetric highs and a low ridge, a topography that would imply three separate volcanoes; but the plume-headmodel indicates a single massive volcano. Based on multichannel seismic profiles and rock samples from Integrated Ocean Drilling Program core sites, Tamu Massif appears to be a single massive volcano made of lava flows that emanated from the volcano centre and formed its shield shape; however, the profiles have large gaps in them, leaving open the possibility that it may represent the activity of more than one volcano. A subsequent study in 2016 found that the massif was likely generated by a single volcano. In 2015, researchers found that the volcano's structure bore patterns of magnetic striping on either side, indicating that the volcano is likely a hybrid of a mid-ocean ridge and a shield volcano. Geologic data also indicated that Tamu Massif formed at the junction of three mid-ocean ridges, which was a highly unusual occurrence. A study found that the Moho line, the boundary between the Earth's crust and mantle, extends more than beneath the base of Tamu Massif, meaning that the volcano is unlikely to ever erupt again, since magma is almost unable to penetrate a barrier that thick.
