Brothers volcano

Brothers volcano is one of about 70 volcanoes that form the roughly 2500 km long largely submarine Tonga-Kermadec arc. The volcano is three times the size of White Island and forms a 1900-meter-high volcano with a deep central caldera (collapse crater). Within the caldera a volcanic cone rises hundreds of meters above the volcanic floor.

Brothers volcano was only discovered in the 1990s, with the first survey undertaken by the New Zealand research vessel Tangaroa in 1996. Since then the volcano has been re-surveyed several times with different methods, producing seafloor maps, photographic and video imagery, rock and biological samples.

The eruptive history, including that of any recent eruptions is still unknown. The crater walls reveal layers of lava flows from which a later eruption has blown out a caldera. Lavas recovered are mostly black and glassy silica-rich dacites

At present Brothers is the most hydrothermally active and mineral-rich volcano known in the Kermadec Arc. The central caldera hosts large vent-fields with up to 20 m high mineral-rich chimneys (so called ‘black smokers’). Whole forests of chimneys grow, as fluids, superheated by 1000˚C magma deep within the volcano, are expelled into the sea water. The ‘black smoke’ forms when these hot, battery-acid-like fluids come in contact with 4˚C cold seawater and dissolved sulphides precipitate as black sulphide particles. These particles rain down, or are stacked on top of each other and can build a gold, silver and copper-rich black-smoker chimney within weeks or month.

The hydrothermal vent fields are also sites were unique sea-life has settled. Extremophile bacteria that gain their energy from the hot fluids, feed larger animals, such as shrimp and white crabs to form a food web.

Have a good look around the 3D image and think about the different features that you can see.
How far below sea level is the tip of the cone? Can you measure the width of the caldera, and work out its depth from the top of the rim?
If you look on Google Earth, or in an atlas, you can compare the size of the caldera with Wellington Harbour to give you an idea of the scale of this impressive volcano.

In 2018 Brothers volcano is being drilled by the Joides Resolution run by the International Ocean Drilling Program (IODP). This is epically cool research! Click on the links for lots more information...