South Kermadec Ridge Seamounts Explained

South Kermadec Ridge Seamounts
Location:	South Pacific Ocean
Coordinates:	-35.5°N 178.2°W
Type:	Seamount chain

The South Kermadec Ridge Seamounts are a continuation of the volcanic island arc,^[1] formed at the convergent boundary where the Pacific Plate subducts under the Indo-Australian Plate. The subducting Pacific Plate created the Kermadec Trench,^[2] the second deepest submarine trench,^[3] to the east of the islands. The seamounts lie along the western aspect of the undersea Kermadec Ridge, which runs southwest from the Kermadec Islands towards the North Island of New Zealand and northeast towards Tonga (Kermadec-Tonga Arc).

This area of the Kermadec Arc - Havre Trough is a relatively young oceanic arc-back-arc system as it became active in the Quaternary.^[4] The seamounts include:^{[5] [4] [6] [7]}

• Speight Knoll -1840m (-6,030feet)-32.3883°N 179.591°W^[7]
• Oliver Knoll -2200m (-7,100feet)-32.3945°N 179.6723°W^[7]
• Haungaroa Seamount -660m (-2,160feet)-32.6152°N 179.6217°W^[7]
• Kuiwai Seamount -560m (-1,830feet)-33.159°N 179.9565°W^[7]
• Cole Seamount -33.4095°N 179.8715°W^[7]
• Ngātoroirangi Seamount -340m (-1,110feet)-33.7353°N 179.7967°W^[7]
• Sonne Seamount -34.0667°N 179.5833°W^[7]
• Kibblewhite Seamount -990m (-3,240feet)-34.5762°N 179.262°W^[7]
• Gill Seamount -1200m (-3,800feet) -34.62°N 178.375°W
  • Situated in the middle of a deep basin (3000m deep) in the Havre Trough, to the west of Kibblewhite and actually closer to the Lau-Colville Ridge than the Kermadec Ridge^[4]
  • Basalt age 1.1 ± 0.4 Ma^[8]
• Yokosuka Seamount -1060m (-3,470feet) -34.7°N 178.57°W
  • To west of Brothers situated on an elevated basal plateau (2500m deep)^[4]
• Rapuhia Seamount -650m (-2,120feet) -34.77°N 178.5°W
  • To west of Brothers^[4]
• Gilianes Seamount -700m (-2,200feet) -34.77°N 178.58°W
  • To west of Brothers^[4]
• Brothers Seamount -1350m (-4,420feet) -34.875°N 179.075°W ^[6]
• Healy -1150m (-3,760feet) -35°N 178.9°W ^[6]
  • Two calderas in a 15km (09miles) elongated complex with the largest caldera being 3 x 4 km
    • This is believed to have been formed in the 1360 ± 75 CE eruption
  • Cotton -980m (-3,210feet) -35.004°N 178.973°W ^[6]
    • Satellitic cone to Healy at south west end of complex
• The Silents
  • Silent I Seamount^[9]
  • Silent II Seamount -850m (-2,780feet) -35.1599°N 178.8681°W^{[7] [9]}
• The Rumbles
  • Rumble I Seamount -1100m (-3,500feet) -35.5°N 178.9°W ^[6]
  • Rumble II West Seamount -1200m (-3,800feet) -35.353°N 178.527°W ^[6]
  • Rumble II East Seamount -850m (-2,780feet) -35.4292°N 178.6548°W^[7]
  • Rumble III Seamount -140m (-450feet) -35.745°N 178.478°W ^[6]
    • Largest of the chain of Rumble seamounts
    • Eruptions on:^[10]
      • 9 July 1958
      • 16 January 1963
      • 15 October 1973
      • 15 June 1986
      • 2 July 2008
  • Rumble IV Seamount -450m (-1,470feet)-36.13°N 178.05°W ^[6]
  • Rumble V Seamount -1100m (-3,500feet)-36.139°N 178.197°W ^[6]
• Lillie Seamount -1280m (-4,190feet)-35.8696°N 178.4355°W^[7]
  • Lillie is north of Rumbles IV and V
• Tangaroa Seamount -600m (-1,900feet) -36.321°N 178.028°W ^[6]
• Clark Seamount -860m (-2,810feet) -36.446°N 177.839°W ^[6]
• Whakatāne Seamount -900m (-2,900feet) -36.7828°N 177.4618°W^{[7] [4]}

Notes and References

1. Wright . I. C. . Nature and tectonic setting of the southern Kermadec submarine arc volcanoes: An overview . Marine Geology . 1994 . 118 . 3–4 . 217–236 . 5 June 2022 . 10.1016/0025-3227(94)90085-X.
2. Billen . M. I.. Gurnis . M.. Constraints on subducting plate strength within the Kermadec trench. 2005 . Journal of Geophysical Research: Solid Earth . 110 . B5. 10.1029/2004JB003308 . 2005JGRB..110.5407B. free .
3. Web site: Deep-Sea Vehicle Nereus Lost 6 Miles Down . National Geographic. https://web.archive.org/web/20220605125703/https://www.nationalgeographic.com/science/article/140512-nereus-deep-sea-vehicle-lost-ocean-technology-science . dead . 5 June 2022 . 5 June 2022.
4. Web site: The Petrology, Geochemistry and Geochronology of Back-Arc Stratovolcanoes in the Southern Kermadec Arc-Havre Trough, SW Pacific. Alexander . Zohrab . 2016 .
5. Ballance. Peter F.. Ablaev . Albert G.. Pushchin. Igor K. Pletnev. Sergei P.. Birylina. Maria G.. Itaya. Tetsumaru. Follas. Harry A.. Gibson. Graham W.. Morphology and history of the Kermadec trench–arc–backarc basin–remnant arc system at 30 to 328S: geophysical profile, microfossil and K–Ar data. 1999 . Marine Geology . 159 . 1–4. 35–62. 10.1016/S0025-3227(98)00206-0. 5 June 2022 .
6. Web site: Global Volcanism Program Database . 2022-06-11.
7. Web site: VLIMAR Gazetteer.
8. Richard . Wysoczanski. Graham . Leonard. James . Gill. Ian . Wright. Andrew. Calvert. William . McIntosh. Brian . Jicha. John . Gamble. Christian . Timm. Monica . Handler. Elizabeth . Drewes-Todd . Alex . Zohrab . 2019. Ar-Ar age constraints on the timing of HavreTrough opening and magmatism. New Zealand Journal of Geology and Geophysics. 62 . 3 . 371–377 . 10.1080/00288306.2019.1602059. 10468/7735. free.
9. John H. Latter, Edwards F. Lloyd, Ian E.M. Smith, and Simon Nathan. New Zealand's volcanoes: Kermadec Islands . Volcanic Hazards Working Group, Civil Defence Scientific Advisory Committee.
10. Wunderman, R. Report on Rumble III (New Zealand) — February 2011. Bulletin of the Global Volcanism Network. 36. 1. Smithsonian Institution . 10.5479/si.GVP.BGVN201102-241130 . 2022-06-11.