[3] There is now detailed magnetic anomaly mapping of the Brothers caldera with very extreme range variation from −2000 to +2000 nT.

[3][1] These hydrothermal vents are also known as hot springs and have created an 8 meter high field of "black smoker" chimneys.

[4] These chimneys are created when the hydrothermal fluids hit the cold water and the chemicals in solution are deposited.

[4] The marine life and minerals found from these chimneys are beneficial to New Zealand's economy and biotechnology industry.

[4] Drill samples of hydrothermally altered volcanoclastics products and lava flows of dacitic composition show a two stage history:[1] This sequence was established by a joint expedition by the United States, New Zealand and Germany that mapped the volcano in detail in 2007,[5] and cores of the volcano and its hydrothermal systems that were taken during IODP Expedition 376 (D/V JOIDES Resolution, May–July 2018).