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Hunga Tonga–Hunga Haʻapai

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Hunga Tonga-Hunga Haʻapai is a volcano located about 30 km south-southeast of Fonuafoʻou (also known as Falcon Island),[1] part of Tonga.

The volcano is part of the highly active Tonga-Kermadec Islands volcanic arc, a subduction zone extending from New Zealand north-northeast to Fiji.[2][3] The volcano lies about 100 km (62 miles) above a very active seismic zone.[3][4] Magma is formed as two tectonic plates[5] melt together under high heat and pressure, and the superheated rock is forced to the surface.[4][6]

Volcano and caldera

NASA satellite image of Falcon Island (in red), showing Hunga Tonga-Hunga Haʻapai (in green)

The volcano itself is a submarine volcano[7] lying underwater between the two islands, which are the remnants of the western and northern rim of the volcano's caldera.[1] The two islands (part of the Haʻapai group)[8] are about 1.6 km (1 mile) apart,[9] and each is about 2 km (1.2 miles) long and composed largely of andesite.[3][4] Hunga Tonga reaches an elevation of 149 m (489 feet), while Hunga Haʻapai comes to only 128 m (420 feet) above sea level.[1] Neither island is large: Hunga Tonga is roughly 39 hectares (0.15 square miles) and Hunga Haʻapai is 65 hectares (0.25 square miles) in size.[10] Neither island is developed due to a lack of an acceptable anchorage, although there are large guano deposits on each island.[8][11]

Submarine eruptions at a rocky shoal about 3.2 km (1.9 miles) southeast of Hunga Haʻapai and 3 km (1.8 miles) south of Hunga Tonga were reported in 1912 and 1937.[1] Another eruption occurred from a fissure 1 km (0.62 miles) south-southeast of Hunga Haʻapai in 1988.[1]

The islands figure in Tongan mythology as one of the few islands which were not overfished, and hence thrown down from heaven to land on earth.[12][13] Tongans called them the islands which "jump back and forth" (i.e. suffer earthquakes).[12] The first Europeans to see the islands were those with the Dutch explorers Willem Schouten and Jacob Le Maire in 1616, although the British explorer Captain James Cook visited them several times in 1777 and learned their Tongan names.[14]

2009 eruption

Main article: 2009 Tonga undersea volcanic eruption

On March 16, 2009, a submarine eruption near Hunga Tonga-Hunga Haʻapai began spewing steam, smoke, pumice, and ash thousands of feet into the sky above the ocean.[15][16] By March 21, Tonga's chief geologist, Kelepi Mafi reported, lava and ash from two vents, one on the uninhabited island Hunga Haʻapai and another about 100 metres (330 feet) offshore, had filled the gap between the two vents, creating new land surface that measured hundreds of square metres.[17][18] The eruption devastated Hunga Haʻapai, covering it in black ash and stripping it of vegetation and fauna.[18]

False-color satellite image taken March 25, 2009, showing new land south of Hunga Haʻapai. Clouds cover the space between the new land and Hunga Haʻapai. The vent is the nearly perfect circular hole near the southern edge of the new land. The ocean around the erupting volcano is bright blue, indicating ash, rock, and other volcanic debris. Plant-covered land is red. Note that Hunga Haʻapai is now colored black, indicating that plants on the island are now buried in ash or dead.

See also

References

  1. ^ a b c d e "Hunga Tonga-Hunga Ha'apai". Global Volcanism Program. Smithsonian Institution.
  2. ^ Clift, Peter D.; Rose, Estelle F.; Shimizu, Nobumichi; Layne, Graham D.; Draut, Amy E.; and Regelous, Marcel. "Tracing the Evolving Flux From the Subducting Plate in the Tonga-Kermadec Arc System Using Boron in Volcanic Glass." Geochimica et Cosmochimica Acta. 65:19 (October 2001).
  3. ^ a b c Gupta, Alok K. Igneous Rocks. Mumbai, India: Allied Publishers, 1998. ISBN 817023784X
  4. ^ a b c Ewart, A.; Bryan, W.B.; and Gill, J.B. "Mineralogy and Geochemistry of the Younger Volcanic Islands of Tonga, S.W. Pacific." Journal of Petrology. 14:3 (1973).
  5. ^ The island arc is formed at the convergent boundary where the Pacific Plate subducts under the Indo-Australian Plate.
  6. ^ Ewart, A. "A Petrological Study of the Younger Tongan Andesites and Dacites, and the Olivine Tholeiites of Niua Fo'ou Island, S. W. Pacific." Contributions to Mineralogy and Petrology. 58:1 (January 1976); Hawkesworth, C.J.; Turner, S.P.; McDermott, F.; Peate, D.W.; and van Calsteren, P. "U-Th Isotopes in Arc Magmas: Implications for Element Transfer from the Subducted Crust." Science. 276:5312 (April 25, 1997).
  7. ^ Arnberger, Erik. The Tropical Islands of the Indian and Pacific Oceans. Vienna: Austrian Academy of Sciences Press, 2001. ISBN 3700127383
  8. ^ a b Wells, Susan M.; Sheppard, Charles; and Jenkins, Martin. Coral Reefs of the World: Central and Western Pacific. United Nations Environment Programme, 1988. ISBN 2880329450
  9. ^ Pacific Islands Pilot. London: Great Britain Hydrographic Department, 1969.
  10. ^ Dahl, Arthur L. Review of the Protected Areas System in Oceania. IUCN Commission on National Parks and Protected Areas. United Nations Environment Programme, 1986. ISBN 2880325099
  11. ^ Fletcher, Matt and Keller, Nancy J. Tonga. Oakland, Calif.: Lonely Planet, 2001. ISBN 1740590619; Bulletin - Department of Minerals and Energy, Bureau of Mineral Resources, Geology and Geophysics. Australia Bureau of Mineral Resources, Geology and Geophysics, 1964.
  12. ^ a b Gifford, Edward Winslow. Tongan Myths and Tales. London: The British Museum, 1924.
  13. ^ Nunn, Patrick D. "Fished Up or Thrown Down: The Geography of Pacific Island Origin Myths." Annals of the Association of American Geographers. 93:2 (November 2004).
  14. ^ Suren, Peter. Essays on the History of the Discovery and Exploration of Tonga by the Europeans. Nukuʼalofa, Kingdom of Tonga: Friendly Islands Bookshop, 2001; Rutherford, Noel. Friendly Islands: A History of Tonga. Cambridge: Oxford University Press, 1977. ISBN 0195505190; Cook, James. The Journals of Captain Cook. John Cawte Beaglehole and Philip Edwards. New York: Penguin Classics, 1999. ISBN 0140436472
  15. ^ "Tongan Inspectors Head to Undersea Volcano." Associated Press. March 19, 2009.
  16. ^ The date the eruption began is uncertain. According to the Smithsonian Institution's Global Volcanism program, "Observers flying near the area of Hunga Tonga-Hunga Ha'apai (about 62 km NNW of Nuku'alofa, the capital of Tonga) on 16 or 17 March reported seeing an eruption." See: SI/USGS Weekly Volcanic Activity Report. 11 March-17 March 2009. The report cites Keizo Gates' Web log, dated March 16, 2009, which contains photos allegedly taken from civilian aircraft late on the afternoon of March 16. See: Gates, Keizo. "New Tonga Eruption" Kzo.net. March 16, 2009. The Smithsonian subsequently confirmed that the eruption began on March 16. See: SI/USGS Weekly Volcanic Activity Report. 18 March-24 March 2009.
  17. ^ Percival, Jenny. "Underwater Volcano Creates New Island Off Tonga." The Guardian. 21 March 2009.
  18. ^ a b "'No Living Thing Left' As Tonga Volcano Erupts." Agence France Presse. March 20, 2009.
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