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Niuatahi, also known as Volcano O or MTJ-1,[2] is a nearly circular submarine caldera in the Tonga Islands of the South Pacific Ocean. The volcano is 15 km (9.3 mi) across, and rises 1,340 m (4,400 ft) above the seafloor. The caldera is 9 km (5.6 mi) wide.[3] The caldera floor lies about 2 km (1.2 mi) under the ocean, although a 730 m (2,400 ft) high volcanic cone inside the caldera named Motutahi rises to 1,270 m (4,170 ft) below sea level. The volcano is surrounded by lava flows extending 60 km (37 mi) from the caldera.[3] Dacite is the primary volcanic rock composing Motutahi and the surrounding caldera floor. Hydrothermal venting takes place adjacent to the inner caldera walls and on the summit of Motutahi.[1][2]

Niuatahi
Highest point
Elevation	−1,270 metres (−4,170 ft)[1]
Listing	List of volcanoes in Tonga
Coordinates	15.379°S 174.003°W / -15.379; -174.003
Geography
Location	Tonga Islands
Geology
Mountain type	Caldera
Last eruption	Unknown[1]

Niuatahi was named by the Tonga Ministry of Lands, Environment, Climate Change and Natural Resources. In the Tongan language, Niuatahi means sea. The name Motutahi means island in the sea in the Tongan language.[1]

See also

• List of volcanoes in Tonga

References

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