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  • Country
  • Volcanic Region
  • Primary Volcano Type
  • Last Known Eruption
  • 34.875°S
  • 179.075°E

  • -1350 m
    -4428 ft

  • 241150
  • Latitude
  • Longitude

  • Summit

  • Volcano

The Global Volcanism Program has no activity reports for Brothers.

The Global Volcanism Program has no Weekly Reports available for Brothers.

Index of Monthly Reports

Reports are organized chronologically and indexed below by Month/Year (Publication Volume:Number), and include a one-line summary. Click on the index link or scroll down to read the reports.

07/2007 (BGVN 32:07) 2007 cruise found submarine volcano in repose with active hydrothermal plumes

Contents of Monthly Reports

All information contained in these reports is preliminary and subject to change.

All times are local (= UTC + 12 hours)

07/2007 (BGVN 32:07) 2007 cruise found submarine volcano in repose with active hydrothermal plumes

In the latest of several investigations since 1996, scientists again explored Brothers submarine volcano, working there during 28 July-16 August 2007 (figure 1). The German research ship RV Sonne provided the platform for these 2007 investigations, which included bathymetric mapping, measurements of the water column, and observations of hydrothermal activity. This report summarizes some of the mapping and basic observations made at Brothers on this recent and past cruises.

Figure 1. Regional tectonic map indicating the location of Brothers submarine volcano along the active volcanic front. Abbreviations: C = Curtis Island; CLSC = Central Lau spreading center; ELSC = Eastern Lau spreading center; M = Macauley Island; NFSC = North Fiji spreading center; R = Raoul Island, TVZ = Taupo volcanic zone; W = White Island. After de Ronde and others (2005).

Brothers rests along the active Kermadec arc at a point ~ 450 km NE offshore of New Zealand's North Island (figure 1). For reference, the volcano White Island lies ~ 50 km off the coast in the Bay of Plenty at the N end of North Island ("W," figure 1). Parts of Brothers have been explored previously from surface ships and submersibles, documenting the volcano as hydrothermally active but not in eruption.

Earlier surveys at Brothers. In February 1996, the first sulfide samples from the southern Kermadec arc were dredged from Brothers. On a cruise in late 1998, New Zealand scientists confirmed that Brothers hosted active hydrothermal vents. Using towed cameras and videos, scientists observed tall chimneys perched on the NW caldera's steep walls. On that 1998 cruise, scientists also saw clear evidence of hot, metal- and sulfur-rich fluids expelled from inside the caldera. Numerous samples from Brothers have been acquired and analyzed (for example, see de Ronde and others, 2005).

Other cruises during 1999, 2002, and 2004 mapped and sampled black smokers and other hydrothermal plumes that emanated from the numerous active chimneys. In late 2004, scientists dove four times on vent sites with the Japanese manned submersible Shinkai 6500, followed in 2005 by five dives with the American submersible Pisces V.

2007 report of investigations. The 2007 cruise (called the New Zealand American Submarine Ring of Fire 2007) represented a collaboration between the Geological and Nuclear Sciences–GNS (New Zealand), the Leibniz Institute for Sea Sciences at the University of Kiel ( das Leibniz-Institut für Meereswissenschaften an der Universität Kiel—IFM GEOMAR) (Germany), the National Oceanic and Atmospheric Administration's Ocean Exploration (NOAA-OE) program (USA), and the Woods Hole Oceanographic Institution (USA). Logs of the cruise, available on a NOAA website, and the paper by de Ronde and others (2005) provided much of the information for this preliminary report.

Bathymetric information was used to create an oblique relief image of the 350-m-high intracaldera cone with the caldera floor and walls in the background (figure 2). A hydrothermal area lies along the caldera's NW wall and hydrothermal chimneys were seen there (figure 3). Diffuse venting was also reported from the prominent and smaller cones.

Figure 2. (Left) A bathymetric map based on EM 300 multibeam soundings and depicting Brothers with a contour interval of 200 m. Much of the sea floor surrounding the edifice at distances of several kilometers away lies below 2,200 m depth. Much of the volcano's rim lies at ~ 1,400 m depth. Fluids as hot as 300°C vented at the two identified hydrothermal areas. (Right) An oblique, three-dimensional view of Brothers looking NW (with 3-fold vertical exaggeration) in a graphic prepared at the end of the 2007 cruise. The caldera's dimensions are 3-by-4 km. Although a vertical scale corresponding to the shading is absent, the large cone in the left foreground rises ~ 350 m above the caldera floor. Both that summit crater and the smaller cone to the NE (right) discharged hydrothermal emissions. The rough, sometimes blocky material exposed along the caldera wall consists of older, pre-caldera lavas and other volcanic rocks. Courtesy of New Zealand American Submarine Ring of Fire 2007 Exploration.
Figure 3. An active hydrothermal chimney (commonly known as a "black smoker") photographed at Brothers at the NW caldera hydrothermal site during the 2007 cruise. The dark color of the vented material is thought to result from particulates. Image courtesy of New Zealand American Submarine Ring of Fire 2007 Exploration.

The existence of active thermal features at Brothers also comes from observations of seawater turbidity (i.e., cloudiness of the water column, analogous to the plume in figure 3). Basically, areas of high turbidity signify hydrothermal venting (figure 4). In more detail, turbidity, when considered along with collateral data (such as seawater velocity over the ocean floor, electrical conductivity, temperature, and samples of water and rock) may provide clues about the strength, chemistry, and location of the hydrothermal venting.

Figure 4. A cross-section depicting the sea-floor topography and the result of light-scattering measurements (turbidity of the water column) at Brothers, drawn from SE to NW. Bottom topography (exaggerated) is shown corresponding to the scale at left. Shading indicates the level of turbidity (i.e., cloudiness, haziness, or lack of clarity) as measured in the change in (delta) nephelometric turbidity units (îNTU), a nondimensional optical standard contrasting measured turbidity to that of local ambient water. High îNTU values indicate increased particulate within the hydrothermal plume. Note the regions of high îNTU adjacent the NW caldera wall and the summit of the caldera cone, areas indicated as focal points for hydrothermal venting. The thin black line traces the path of the CTD (conductivity/temperature/depth) sensors towed at various depths along the cross-section. Image courtesy of New Zealand American Submarine Ring of Fire 2007 Exploration.

Metal deposits. One goal of the 2007 expedition was to better understand hydrothermal venting and its relation to metal-bearing deposits at Brothers. Hydrothermal vents, which might be active for periods from months to decades, may contribute to mineral deposits along the Kermadec arc. Investigators developed a hypothetical diagrammatic cross section through Brothers presenting a model of its internal intrusive processes and thermal and hydrothermal evolution (de Ronde and others, 2005).

Submersibles. Technology used to study Brothers included two well-instrumented submersibles.

One submersible was a torpedo-like autonomous underwater vehicle known as the Autonomous Benthic Explorer (ABE), from Woods Hole Oceanographic Institution. ABE was intended to 'fly' above the surface of the crater in a grid pattern. ABE's instrumentation includes a fluxgate magnetometer, swath (wide-angle) bathymetry using multibeam sonar, and instruments to measure conductivity, temperature, depth, and water chemistry. ABE assesses its relationship to the sea floor to within several meters by using sonar and satellite guidance systems. Typically it operates ~ 25 m above the sea floor on a programmed path for up to 16 hours before surfacing to recharge its batteries.

The other submersible was a new remotely operated, tethered vehicle–the SeaQuest 6000. It connects to the ship by a fiber-optic cable, contains numerous instruments, and carries manipulator arms and video cameras. Available reports noted that on the cruise, SeaQuest 6000 examined previously identified seafloor features in more detail.

References. de Ronde, C. E. J. , Hannington, M.D., Stoffers, P., Wright, I.C., Ditchburn, R.G., Reyes, A.G., Baker, E.T., Massoth, G.J., Lupton, J.E., Walker, S.L., Greene, R.R., Soong, C.W.R., Ishibashi, J., Lebon, G.T., Bray, C.J., and Resing, J.A., 2005, Evolution of a Submarine Magmatic-Hydrothermal System: Brothers Volcano, Southern Kermadec Arc, New Zealand: Economic Geology, v. 100, no. 6, p. 1097-1133.

Smith, W. H. F., and Sandwell, D.T., 1997, Global seafloor topography from satellite altimetry and ship depth soundings: Science, v. 277, p. 1957-1962, 26 Sept. 1997.

Information Contacts: Institute of Geological and Nuclear Sciences (GNS), Private Bag 2000, Wairakwi, New Zealand (URL:; The Leibniz Institute for Sea Sciences at the University of Kiel, IFM-GEOMAR, Kiel, Germany; US National Oceanic and Atmospheric Agency (NOAA) (URL:; Woods Hole Oceanographic Institution, Woods Hole, MA 02543 USA (URL:

The submarine Brothers volcano, located NE of the Healy submarine volcano, contains an oval-shaped summit caldera 3-3.5 km wide. The volcano is elongated in a NW-SE direction, and the high point of the dominantly dacitic volcano lies on the NW caldera rim at about 1350 m below the sea surface. The caldera floor is at about 1850 m depth, and a post-caldera lava dome was constructed on the southern caldera floor and partially merges with the southern caldera wall. Brothers volcano displays major submarine hydrothermal activity, including a large field of "black smoker" vents on the NW caldera wall and vents on the post-caldera dome.

The Global Volcanism Program is not aware of any Holocene eruptions from Brothers. If this volcano has had large eruptions (VEI >= 4) prior to 10,000 years ago, information might be found on the Brothers page in the LaMEVE (Large Magnitude Explosive Volcanic Eruptions) database, a part of the Volcano Global Risk Identification and Analysis Project (VOGRIPA).

The Global Volcanism Program has no synonyms or subfeatures listed for Brothers.

Map view of Brothers submarine volcano. The NZASRoF 2005 Pisces V dives are indicated in the northwest caldera area. The contour interval is 100 meters. The resolution of the bathymetry data is 25 meters. The bathymetry data are provided courtesy of the New Zealand National Institute of Water and Atmospheric Research.

Image courtesy of New Zealand-American Submarine Ring of Fire 2005 Exploration, NOAA Vents Program.
Major submarine hydrothermal activity is present at Brothers volcano. This tall (up to 4 meters high), active black smoker chimney is part of a large field of vents on the NW caldera wall. The oval-shaped caldera is 3-3.5 km wide and contains a post-caldera lava dome constructed on the southern caldera floor.

Image courtesy of New Zealand-American Submarine Ring of Fire 2005 Exploration, NOAA Vents Program.

The following references have all been used during the compilation of data for this volcano, it is not a comprehensive bibliography. Discussion of another volcano or eruption (sometimes far from the one that is the subject of the manuscript) may produce a citation that is not at all apparent from the title.

de Ronde, C E J, Baker E T, Massoth G J, Lupton J E, Wright I C, Feely R A, Greene R R, 2001. Intra-oceanic subduction-related hydrothermal venting, Kermadec volcanic arc, New Zealand. Earth Planet Sci Lett, 193: 359-369.

Haase K M, Stroncik N, Garbe-Schonberg D, Stoffers P, 2006. Formation of island arc dacite magmas by extreme crystal fractionation: an example from Brothers Seamount, Kermedec island arc (SW Pacific). J Volc Geotherm Res, 152: 316-330.

Massoth G J, de Ronde C E J, Lupton J E, Feely R A, Baker E T, Lebon G T, Maenner S M, 2003. Chemically rich and diverse submarine hydrothermal plumes of the southern Kermadec volcanic arc (New Zealand). Geol Soc London Spec Pub, 219: 119-139.

NIWA/NOAA Vents Program, 2005. New Zealand American submarine ring of fire 2005 Kermadec arc submarine volcanoes. New Zeal Nat Inst Water Atmosph Res/NOAA Vents Program final cruise report (

Wright I C, Gamble J A, 1999. Southern Kermadec submarine caldera arc volcanoes (SW Pacific): caldera formation by effusive and pyroclastic eruption. Marine Geol, 161: 207-227.

Wright I C, Worthington T J, Gamble J A, 2006. New multibeam mapping and geochemistry of the 30°-35° S sector, and overview, of southern Kermadec arc volcanism. J Volc Geotherm Res, 149: 263-296.

Volcano Types

Lava dome

Tectonic Setting

Subduction zone
Oceanic crust (< 15 km)

Rock Types

Basalt / Picro-Basalt


Within 5 km
Within 10 km
Within 30 km
Within 100 km

Affiliated Databases

Large Eruptions of Brothers Information about large Quaternary eruptions (VEI >= 4) is cataloged in the Large Magnitude Explosive Volcanic Eruptions (LaMEVE) database of the Volcano Global Risk Identification and Analysis Project (VOGRIPA).
WOVOdat WOVOdat is a database of volcanic unrest; instrumentally and visually recorded changes in seismicity, ground deformation, gas emission, and other parameters from their normal baselines. It is sponsored by the World Organization of Volcano Observatories (WOVO) and presently hosted at the Earth Observatory of Singapore.
EarthChem EarthChem develops and maintains databases, software, and services that support the preservation, discovery, access and analysis of geochemical data, and facilitate their integration with the broad array of other available earth science parameters. EarthChem is operated by a joint team of disciplinary scientists, data scientists, data managers and information technology developers who are part of the NSF-funded data facility Integrated Earth Data Applications (IEDA). IEDA is a collaborative effort of EarthChem and the Marine Geoscience Data System (MGDS).
Smithsonian Collections Search the Smithsonian's NMNH Department of Mineral Sciences collections database. Go to the "Search Rocks and Ores" tab and use the Volcano Name drop-down to find samples.