Brothers Volcano

The Brothers Volcano is a Pacific Ocean submarine volcano in the Kermadec Arc, 340 kilometres north east of New Zealand's Whakaari/White Island. Within its oval outline, which measures 13 km by 8 km, it contains a 3 km wide caldera with walls 300-500 m high. It is three times bigger than the White Island.[1] A dacite (dacite lava's viscosity is in between rhyolite and andesite[1]) dome rises 350 m from the caldera floor (which lies 1850 m below sea level), with a smaller dome just to its northeast.[2]

Brothers Volcano
Brothers Volcano as looking into the caldera from the south
Summit depth	1,350 m (4,430 ft)
Location
Coordinates	34.875°S 179.075°E / -34.875; 179.075
Geology
Type	Submarine volcano
Last eruption	Unknown

"Black Smoker" Chimneys

The caldera walls and the larger dome host numerous hydrothermal vents, which send plumes of hot water 750 m up through the water column. It is the most hydrothermally active volcano known in the Kermadec Arc.[2] These hydrothermal vents are also known as hot springs and have created an 8 meter high field of "black smoker" chimneys.[3] These chimneys are created when the hydrothermal fluids hit the cold water and the chemicals in solution are deposited.[1] The hydrothermal fluids are an energy source to many unique species of organisms like tubeworms and bacteria.[3] The marine life and minerals found from these chimneys are beneficial to New Zealand's economy and biotechnology industry.[1]

The volcano was created by subduction of the Pacific Plate under the Australian Plate.[1] It is still unknown when the Brothers Volcano last erupted, but the crater walls tell us that its last eruption was so explosive that it caused the volcano to blow out a caldera.[3] A joint expedition by the United States, New Zealand and Germany mapped the volcano in detail in 2007.[4]