Mariana Trench

The Mariana Trench or Marianas Trench[1] is located in the western Pacific Ocean about 200 kilometres (124 mi) east of the Mariana Islands; it is the deepest oceanic trench on Earth. It is crescent-shaped and measures about 2,550 km (1,580 mi) in length and 69 km (43 mi) in width. The maximum known depth is 10,984 ± 25 metres (36,037 ± 82 ft; 6.825 ± 0.016 mi) at the southern end of a small slot-shaped valley in its floor known as the Challenger Deep.[2] If Mount Everest were hypothetically placed into the trench at this point, its peak would still be underwater by more than 2 kilometres (1.2 mi).[lower-alpha 1]

Location of the Mariana Trench

At the bottom of the trench, the water column above exerts a pressure of 1,086 bars (15,750 psi), more than 1,071 times the standard atmospheric pressure at sea level. At this pressure, the density of water is increased by 4.96%. The temperature at the bottom is 1 to 4 °C (34 to 39 °F).[5]

In 2009, the Mariana Trench was established as a US National Monument.[6] Monothalamea have been found in the trench by Scripps Institution of Oceanography researchers at a record depth of 10.6 kilometres (6.6 mi) below the sea surface.[7] Data has also suggested that microbial life forms thrive within the trench.[8][9]

Etymology

The Mariana Trench is named after the nearby Mariana Islands, which are named Las Marianas in honor of Spanish Queen Mariana of Austria, widow of Philip IV of Spain. The islands are part of the island arc that is formed on an over-riding plate, called the Mariana Plate (also named for the islands), on the western side of the trench.

Geology
The Pacific plate is subducted beneath the Mariana Plate, creating the Mariana trench, and (further on) the arc of the Mariana Islands, as water trapped in the plate is released and explodes upward to form island volcanoes and earthquakes.

The Mariana Trench is part of the Izu–Bonin–Mariana subduction system that forms the boundary between two tectonic plates. In this system, the western edge of one plate, the Pacific Plate, is subducted (i.e., thrust) beneath the smaller Mariana Plate that lies to the west. Crustal material at the western edge of the Pacific Plate is some of the oldest oceanic crust on Earth (up to 170 million years old), and is, therefore, cooler and denser; hence its great height difference relative to the higher-riding (and younger) Mariana Plate. The deepest area at the plate boundary is the Mariana Trench proper.

The movement of the Pacific and Mariana plates is also indirectly responsible for the formation of the Mariana Islands. These volcanic islands are caused by flux melting of the upper mantle due to the release of water that is trapped in minerals of the subducted portion of the Pacific Plate.

Research history
Ocean trenches in the western Pacific

The trench was first sounded during the Challenger expedition in 1875 using a weighted rope, which recorded a depth of 4,475 fathoms (8,184 metres; 26,850 feet).[10][11] In 1877, a map was published called Tiefenkarte des Grossen Ozeans ("Depth map of the Great Ocean") by Petermann, which showed a Challenger Tief ("Challenger deep") at the location of that sounding. In 1899, USS Nero, a converted collier, recorded a depth of 5,269 fathoms (9,636 metres; 31,614 feet).[12]

In 1951, Challenger II surveyed the trench using echo sounding, a much more precise and vastly easier way to measure depth than the sounding equipment and drag lines used in the original expedition. During this survey, the deepest part of the trench was recorded when the Challenger II measured a depth of 5,960 fathoms (10,900 metres; 35,760 feet) at 11°19′N 142°15′E, known as the Challenger Deep.[13]

In 1957, the Soviet vessel Vityaz reported a depth of 11,034 metres (36,201 ft) at a location dubbed the Mariana Hollow.[14]

In 1962, the surface ship M.V. Spencer F. Baird recorded a maximum depth of 10,915 metres (35,810 ft) using precision depth gauges.

In 1984, the Japanese survey vessel Takuyō (拓洋) collected data from the Mariana Trench using a narrow, multi-beam echo sounder; it reported a maximum depth of 10,924 metres (35,840 ft), also reported as 10,920 ± 10 metres (35,827 ± 33 ft).[15] Remotely Operated Vehicle KAIKO reached the deepest area of the Mariana Trench and made the deepest diving record of 10,911 metres (35,797 ft) on 24 March 1995.[16]

During surveys carried out between 1997 and 2001, a spot was found along the Mariana Trench that had a depth similar to the Challenger Deep, possibly even deeper. It was discovered while scientists from the Hawaii Institute of Geophysics and Planetology were completing a survey around Guam; they used a sonar mapping system towed behind the research ship to conduct the survey. This new spot was named the HMRG (Hawaii Mapping Research Group) Deep, after the group of scientists who discovered it.[17]

On 1 June 2009, mapping aboard the RV Kilo Moana (mothership of the Nereus vehicle), indicated a spot with a depth of 10,971 metres (35,994 ft). The sonar mapping of the Challenger Deep was possible by its Simrad EM120 sonar multibeam bathymetry system for deep water. The sonar system uses phase and amplitude bottom detection, with an accuracy of better than 0.2% of water depth across the entire swath (implying that the depth figure is accurate to ± 22 metres (72 ft)).[18][19]

In 2011, it was announced at the American Geophysical Union Fall Meeting that a US Navy hydrographic ship equipped with a multibeam echosounder conducted a survey which mapped the entire trench to 100 metres (330 ft) resolution.[3] The mapping revealed the existence of four rocky outcrops thought to be former seamounts.[20]

The Mariana Trench is a site chosen by researchers at Washington University and the Woods Hole Oceanographic Institution in 2012 for a seismic survey to investigate the subsurface water cycle. Using both ocean-bottom seismometers and hydrophones, the scientists are able to map structures as deep as 97 kilometres (60 mi) beneath the surface.[21]

Descents
The bathyscaphe Trieste (designed by Auguste Piccard), the first crewed vehicle to reach the bottom of the Mariana Trench[22]

As of 2022, twenty-two crewed descents and seven uncrewed descents have been achieved. The first was the crewed descent by Swiss-designed, Italian-built, United States Navy-owned bathyscaphe Trieste, which reached the bottom at 1:06 pm on 23 January 1960, with Don Walsh and Jacques Piccard on board.[13][23] Iron shot was used for ballast, with gasoline for buoyancy.[13] The onboard systems indicated a depth of 11,521 metres (37,800 ft),[24] but this was later revised to 10,916 metres (35,814 ft).[25] The depth was estimated from a conversion of pressure measured and calculations based on the water density from sea surface to seabed.[23]

This was followed by the uncrewed ROVs Kaikō in 1996 and Nereus in 2009. The first three expeditions directly measured very similar depths of 10,902 to 10,916 m (35,768 to 35,814 ft).[26][27] The fourth was made by Canadian film director James Cameron on 26 March 2012. He reached the bottom of the Mariana Trench in the submersible vessel Deepsea Challenger, diving to a depth of 10,908 metres (35,787 ft).[28][29][30]

In July 2015, members of the National Oceanic and Atmospheric Administration, Oregon State University, and the Coast Guard submerged a hydrophone into the deepest part of the Mariana Trench, the Challenger Deep, never having previously deployed one past a mile. The titanium-shelled hydrophone was designed to withstand the immense pressure 7 miles under.[31] Although researchers were unable to retrieve the hydrophone until November, the data capacity was full within the first 23 days. After months of analyzing the sounds, the experts were surprised to pick up natural sounds like earthquakes, typhoons, baleen whales, and machine-made sounds such as boats.[32] Due to the mission's success, the researchers announced plans to deploy a second hydrophone in 2017 for an extended period of time.

Victor Vescovo achieved a new record descent to 10,928 metres (35,853 ft) on 28 April 2019 using the DSV Limiting Factor, a Triton 36000/2 model manufactured by Florida-based Triton Submarines. He dived four times between 28 April and 5 May 2019, becoming the first person to dive into Challenger Deep more than once.[33][34][35]

On 8 May 2020, a joint project between the Russian shipbuilders, scientific teams of the Russian Academy of Sciences with the support of the Russian Foundation for Advanced Research Projects and the Pacific Fleet submerged the autonomous underwater vehicle Vityaz-D to the bottom of the Mariana Trench at a depth of 10,028 metres (32,900 ft). Vityaz-D is the first underwater vehicle to operate autonomously at the extreme depths of the Mariana Trench. The duration of the mission, excluding diving and surfacing, was more than 3 hours.[36][37]

On 10 November 2020, the Chinese submersible Fendouzhe reached the bottom of the Mariana Trench at a depth of 10,909 metres (35,791 ft).[38][39]

Planned descents

In 2011, Richard Branson announced an intention to send the DeepFlight Challenger single-person submarine to the bottom of the Mariana Trench.[40] The project was cancelled in 2014.[41]

As of February 2012, at least one other team was planning a piloted submarine to reach the bottom of the Mariana Trench.[42]

Life

The expedition conducted in 1960 claimed to have observed, with great surprise because of the high pressure, large creatures living at the bottom, such as a flatfish about 30 cm (12 in) long,[24] and shrimp.[43] According to Piccard, "The bottom appeared light and clear, a waste of firm diatomaceous ooze".[24] Many marine biologists are now skeptical of the supposed sighting of the flatfish, and it is suggested that the creature may instead have been a sea cucumber.[44][45] During the second expedition, the uncrewed vehicle Kaikō collected mud samples from the seabed.[46] Tiny organisms were found to be living in those samples.

In July 2011, a research expedition deployed untethered landers, called drop cams, equipped with digital video cameras and lights to explore this deep-sea region. Among many other living organisms, some gigantic single-celled foraminiferans with a size of more than 10 cm (4 in), belonging to the class of monothalamea, were observed.[47] Monothalamea are noteworthy for their size, their extreme abundance on the seafloor, and their role as hosts for a variety of organisms.

In December 2014, a new species of snailfish was discovered at a depth of 8,145 m (26,722 ft), breaking the previous record for the deepest living fish seen on video.[48]

During the 2014 expedition, several new species were filmed, including huge amphipods known as supergiants. Deep-sea gigantism is the process where species grow larger than their shallow-water relatives.[48]

In May 2017, an unidentified type of snailfish was filmed at a depth of 8,178 metres (26,800 ft).[49]

Pollution

In 2016, a research expedition looked at the chemical makeup of crustacean scavengers collected from the range of 7,841–10,250 metres (25,725–33,629 ft) within the trench. Within these organisms, the researchers found extremely elevated concentrations of PCBs, a chemical toxin banned in the 1970s for its environmental harm, concentrated at all depths within the sediment of the trench.[50] Further research has found that amphipods also ingest microplastics, with 100% of amphipods having at least one piece of synthetic material in their stomachs.[51][52]

In 2019, Victor Vescovo reported finding a plastic bag and candy wrappers at the bottom of the trench.[53] That year, Scientific American also reported that carbon-14 from nuclear bomb testing has been found in the bodies of aquatic animals found in the trench.[54]

Possible nuclear waste disposal site

Like other oceanic trenches, the Mariana Trench has been proposed as a site for nuclear waste disposal in 1972,[55][56] in the hope that tectonic plate subduction occurring at the site might eventually push the nuclear waste deep into the Earth's mantle, the second layer of the Earth. However, ocean dumping of nuclear waste is prohibited by international law.[55][56][57] Furthermore, plate subduction zones are associated with very large megathrust earthquakes, the effects of which are unpredictable for the safety of long-term disposal of nuclear wastes within the hadopelagic ecosystem.[56]

See also
  • Marianas Trench Marine National Monument, United States national monument at the trench. This National Monument protects 246,610 square kilometres (95,216 sq mi) of submerged lands and waters of the Mariana Archipelago. It includes some of the Mariana Trench, but not the deepest part, the Challenger Deep, which lies just outside the monument area.
  • Challenger Deep

Notes
  1. Mariana Trench is 10,994 m deep,[3] while Mount Everest is 8,848 m tall.[4] The difference is 2,146 m, or at least no less than 2,104 m, accounting for the combined 42 m uncertainty in the measurements.

References
  1. "NGA GeoNames Search". National Geospatial Agency. Retrieved 29 February 2016.
  2. Gardner, James V.; Armstrong, Andrew A.; Calder, Brian R.; Beaudoin, Jonathan (2 January 2014). "So, How Deep Is the Mariana Trench?" (PDF). Marine Geodesy. Informa UK Limited. 37 (1): 1–13. doi:10.1080/01490419.2013.837849. ISSN 0149-0419. S2CID 128668687.
  3. "Scientists map Mariana Trench, deepest known section of ocean in the world". The Telegraph. 7 December 2011. Archived from the original on 10 January 2022. Retrieved 23 June 2018.
  4. "Official height for Everest set". BBC News. 8 April 2010. Retrieved 24 June 2018.
  5. "The Temperature in the Mariana Trench". Infoplease. 28 February 2017.
  6. "About the Monument – Mariana Trench". U.S. Fish and Wildlife Service.
  7. "Giant amoeba found in Mariana Trench – 6.6 miles beneath the sea". Los Angeles Times. 26 October 2011. Retrieved 23 March 2012.
  8. Choi, Charles Q. (17 March 2013). "Microbes Thrive in Deepest Spot on Earth". LiveScience. Retrieved 17 March 2013.
  9. Glud, Ronnie; Wenzhöfer, Frank; Middleboe, Mathias; Oguri, Kazumasa; Turnewitsch, Robert; Canfield, Donald E.; Kitazato, Hiroshi (17 March 2013). "High rates of microbial carbon turnover in sediments in the deepest oceanic trench on Earth". Nature Geoscience. 6 (4): 284–288. Bibcode:2013NatGe...6..284G. doi:10.1038/ngeo1773.
  10. "About the Mariana Trench – Deepsea Challenge Expedition". Deepseachallenge.com. 26 March 2012. Archived from the original on 28 June 2013. Retrieved 8 July 2013.
  11. Aitken, Frédéric; Foulc, Jean-Numa (2019). "Chapter 4". From deep sea to laboratory. 1 : the first explorations of the deep sea by H.M.S. Challenger (1872–1876). London. ISBN 9781786303745.
  12. Theberge, A. (24 March 2009). "Thirty Years of Discovering the Mariana Trench". Hydro International. Retrieved 31 July 2010.
  13. "The Mariana Trench – Exploration". marianatrench.com.
  14. "Mariana Trench". Encyclopædia Britannica.
  15. Tani, S. "Continental shelf survey of Japan" (PDF). Archived from the original (PDF) on 9 March 2011. Retrieved 24 December 2010.
  16. Development and Construction of Launcher System of 10000m‐Class Remotely Operated Vehicle KAIKO Mitsubishi Heavy Industry
  17. Whitehouse, David (16 July 2003). "Sea floor survey reveals deep hole". BBC News. Retrieved 17 December 2011.
  18. "Daily Reports for R/V KILO MOANA June and July 2009". University of Hawaii Marine Center. Archived from the original on 21 January 2010. Retrieved 4 January 2010.
  19. "Inventory of Scientific Equipment aboard the R/V KILO MOANA". University of Hawaii Marine Center. Archived from the original on 13 June 2010.
  20. Duncan Geere (7 February 2012). "Four 'bridges' span the Mariana Trench". Wired. Archived from the original on 11 March 2012. Retrieved 23 March 2012.
  21. "Seismic Survey at the Mariana Trench Will Follow Water Dragged Down into the Earth's Mantle". ScienceDaily. 22 March 2012. Retrieved 23 March 2012.
  22. Strickland, Eliza (29 February 2012). "Don Walsh Describes the Trip to the Bottom of the Mariana Trench". IEEE Spectrum. Retrieved 8 July 2013.
  23. "Mariana Trench". Earthquake Hazards Program. United States Geological Survey. 21 October 2009. Archived from the original on 18 March 2012. Retrieved 23 March 2012.
  24. "NOAA Ocean Explorer: History: Quotations: Soundings, Sea-Bottom, and Geophysics". NOAA Ocean Exploration and Research.
  25. "Bathyscaphe". Encyclopædia Britannica. 18 April 2020. Retrieved 11 November 2020.
  26. "7,000 m Class Remotely Operated Vehicle: KAIKO 7000". Japan Agency for Marine-Earth Science and Technology. Retrieved 11 November 2020.
  27. "Robot sub reaches deepest ocean". BBC. 3 June 2009. Retrieved 11 November 2020.
  28. "A man took a submarine to the deepest place on Earth – and found trash". CBC.ca. Thomson Reuters. 13 May 2019. Retrieved 11 November 2020.
  29. "James Cameron has reached deepest spot on Earth". NBC News. 25 March 2012. Retrieved 25 March 2012.
  30. Broad, William J. (25 March 2012). "Filmmaker in Submarine Voyages to Bottom of Sea". The New York Times. Retrieved 25 March 2012.
  31. Schneider, Kate (7 March 2016). "Eerie sounds from the bottom of the Earth". News.com.au. Retrieved 11 November 2020.
  32. Chappell, Bill (4 March 2016). "Deep-Sea Audio Recordings Reveal A Noisy Mariana Trench, Surprising Scientists". NPR. Retrieved 1 May 2016.
  33. Fitzherbert, Stephanie (13 May 2019). "Deepest Submarine Dive in history, Five Deeps Expedition Conquers Challenger Deep" (PDF). The Five Deeps. Retrieved 11 November 2020.
  34. Loomis, Ilima (3 July 2019). "Limiting Factor Was a Science Opportunity for a Deep-Sea Geologist". Eos. Retrieved 11 November 2020.
  35. Blain, Loz (15 May 2019). "Victor Vescovo and the DSV Limiting Factor have found new depths in the Mariana Trench". New Atlas. Retrieved 11 November 2020.
  36. "Russian Submarine "Vityaz" Reached the Bottom of the Mariana Trench". Russian Geographical Society. 13 May 2020. Retrieved 11 November 2020.
  37. "Vityaz-D explored Mariana Trench according to preinstalled program — developer". TASS. 10 June 2020. Retrieved 11 November 2020.
  38. Westcott, Ben (11 November 2020). "China breaks national record for Mariana Trench manned-dive amid race for deep sea resources". CNN. Archived from the original on 11 November 2020. Retrieved 11 November 2020.
  39. Cheng, Xiang; Liu, Liang (10 November 2020). ""奋斗者"号载人潜水器突破万米海深 潜入全球最深海域" [The "Striver" manned submersible breaks through 10,000 meters and dives into the world's deepest waters]. China Central Television. Retrieved 11 November 2020.
  40. "Richard Branson plans deep-ocean submarine dives". Santa Rosa Press Democrat. 5 April 2011. Retrieved 7 August 2020.
  41. "Richard Branson Quietly Scrapped His Plan to Explore the Bottom of the Sea". Business Insider. Retrieved 17 January 2022.
  42. "Deep Search". DOER Marine. 16 March 2011. Retrieved 2 December 2019.
  43. "Bathyscaphe Trieste | Mariana Trench | Challenger Deep". Geology.com. Retrieved 1 March 2012.
  44. "James Cameron dives deep for Avatar", Guardian, 18 January 2011
  45. "James Cameron heads into the abyss", Nature, 19 March 2012
  46. Woods, Michael; Mary B. Woods (2009). Seven Natural Wonders of the Arctic, Antarctica, and the Oceans. Twenty-First Century Books. p. 13. ISBN 978-0-8225-9075-0. Retrieved 23 March 2012.
  47. "Giant amoebas discovered in the deepest ocean trench". Live Science. Retrieved 26 March 2012.
  48. Morelle, Rebecca (9 December 2014). "New record for deepest fish". BBC News. Retrieved 26 August 2017.
  49. "Ghostly fish in Mariana Trench in the Pacific is deepest ever recorded". CBC News. 25 August 2017. Retrieved 26 August 2017.
  50. Jamieson, Alan J.; Malkocs, Tamas; Piertney, Stuart B.; Fujii, Toyonobu; Zhang, Zulin (13 February 2017). "Bioaccumulation of persistent organic pollutants in the deepest ocean fauna". Nature Ecology & Evolution. 1 (3): 51. doi:10.1038/s41559-016-0051. hdl:2164/9142. ISSN 2397-334X. PMID 28812719. S2CID 9192602.
  51. Jamieson, A. J.; Brooks, L. S. R.; Reid, W. D. K.; Piertney, S. B.; Narayanaswamy, B. E.; Linley, T. D. (28 February 2019). "Microplastics and synthetic particles ingested by deep-sea amphipods in six of the deepest marine ecosystems on Earth". Royal Society Open Science. 6 (2): 180667. Bibcode:2019RSOS....680667J. doi:10.1098/rsos.180667. ISSN 2054-5703. PMC 6408374. PMID 30891254.
  52. Robbins, Gary (5 September 2019). "UCSD discovers surge in plastics pollution off Santa Barbara". Los Angeles Times. Retrieved 5 September 2019.
  53. Street, Francesca (13 May 2019). "Deepest ocean dive recorded: How Victor Vescovo did it". CNN Travel. CNN. Retrieved 13 May 2019.
  54. Levy, Adam (15 May 2019). ""Bomb Carbon" Has Been Found in Deep-Ocean Creatures". Scientific American.
  55. Hafemeister, David W. (2007). Physics of societal issues: calculations on national security, environment, and energy. Berlin: Springer. p. 187. ISBN 978-0-387-95560-5.
  56. Kingsley, Marvin G.; Rogers, Kenneth H. (2007). Calculated risks: highly radioactive waste and homeland security. Aldershot, Hants, England: Ashgate. pp. 75–76. ISBN 978-0-7546-7133-6.
  57. "Dumping and Loss overview". Oceans in the Nuclear Age. Archived from the original on 5 June 2011. Retrieved 18 September 2010.
Wikimedia Commons has media related to Mariana Trench.
This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.