Tamu Massif

Tamu Massif
A bathymetric map of the volcano
Summit depth	1,980 metres (6,500 ft)
Height	4,460 metres (14,620 ft)
Location
Location	Northwest Pacific Ocean
Range	Shatsky Rise
Coordinates	33°N 158°E / 33°N 158°E / 33; 158Coordinates: 33°N 158°E / 33°N 158°E / 33; 158
Geology
Type	Seamount (underwater volcano), shield volcano
Age of rock	144.6 ± 0.8 Ma

Tamu Massif is an extinct submarine shield volcano located in the northwestern Pacific Ocean. The possibility of its nature as a single volcano was announced on 5 September 2013, which, if corroborated, would make Tamu Massif the largest known volcano on Earth. It is located in the Shatsky Rise about 1,600 km (990 mi) east of Japan. Its summit lies about 1,980 m (6,500 ft) below the surface of the ocean, and its base extends to a depth of about 6.4 km (4.0 mi). The volcano is about 4,460 metres (14,620 ft) 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". While other igneous features on the planet are larger, such as the Ontong Java Plateau, it has not yet been determined if they are indeed just one volcano or rather complexes of several volcanoes.

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 (a few million years) and then became extinct. 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, Mauna Loa on the Hawaiian Islands. Tamu's rounded dome extends over an area of 450 km × 650 km (280 mi × 400 mi), totaling more than 260,000 km² (100,000 sq mi), many times larger than Mauna Loa, which has an area of 5,000 km² (1,900 sq mi), 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. While the Shatsky Rise oceanic plateau is comparable in size to California or Japan, Tamu Massif, which is the plateau's oldest and largest edifice, is comparable in size to New Mexico or Britain and Ireland together.