Monowai (seamount)

Monowai
Three-dimensional view of Monowai Volcanic Centre as seen from the south, showing both the Monowai Seamount cone and Monowai Caldera
Location of Monowai Seamount in Oceania
Summit depth	100 metres (330 ft)
Height	1,200 metres (3,900 ft)
Translation	Channel full of water (named for HMNZS Monowai) (from Māori)
Location
Location	Kermadec Ridge, South Pacific Ocean
Coordinates	25°53′S 177°11′W / 25.89°S 177.18°W / -25.89; -177.18[1]
Country	New Zealand
Geology
Volcanic arc/chain	Kermadec Arc
Age of rock	~780,000 years
Last eruption	2017
History
Discovery date	1877-1924

Monowai Seamount is a volcanic seamount to the north of New Zealand. It is formed by a large caldera and a volcanic cone just south-southeast from the caldera. The volcanic cone rises to depths of up to 100 metres (330 ft) but its depth varies with ongoing volcanic activity, including sector collapses and the growth of lava domes. The seamount and its volcanism were discovered after 1877, but only in 1980 was it named "Monowai" after a research ship of the same name.

The subduction of the Pacific plate beneath the Australia plate has given rise to volcanic and hydrothermal activity on the Kermadec Ridge that Monowai is part of. The volcano is located at the site where the Osbourn Trough and the Louisville seamount chain subduct in the Tonga Trench and this subduction process probably has influenced its volcanism. Monowai is one of the most active volcanoes in the Kermadec volcanic arc, with many eruptions since 1977, and perhaps the most active submarine volcano in the world. Volcanic activity is characterised by the emission of gas and discolouration of water, along with seismic activity and a substantial growth rate of the volcano. The ongoing hydrothermal activity has also been observed and hydrothermal vents on Monowai feature a rich variety of fauna.