In this article, You will read about the Oceanic trench and Important Trenches of the World – for UPSC IAS.

Oceanic Trench

Oceanic trenches are topographic depressions of the seafloor, relatively narrow in width, but very long. These oceanographic features are the deepest parts of the ocean floor. Oceanic trenches are a distinctive morphological feature of convergent plate boundaries, along which lithospheric plates move towards each other at rates that vary from a few millimeters to over ten centimeters per year.

A trench marks the position at which the flexed, subducting slab begins to descend beneath another lithospheric slab. Trenches are generally parallel to a volcanic island arc, and about 200 km (120 mi) from a volcanic arc.

Oceanic trenches typically extend 3 to 4 km below the level of the surrounding oceanic floor. Ocean trenches have a highly specialized fauna. The greatest ocean depth measured is in the Challenger Deep of the Mariana Trench, at a depth of 11,034 m (36,201 ft) below sea level.

The longest trench is the Peru-Chile Trench, which extends some 5,900 km (about 3,700 miles) along the west coast of South America.

Oceanic lithosphere moves into trenches at a global rate of about 3 km2/yr.

Subduction Oceanic Trench
Subduction Trench Schematic

Globally, there are over 50 major ocean trenches covering an area of 1.9 million km2 or about 0.5% of the oceans. Trenches that are partially infilled are known as “troughs” and sometimes they are completely buried and lack bathymetric expression.

Hadal zone

  • The hadal zone, also known as the hadopelagic zone, is the deepest region of the ocean, lying within oceanic trenches.
  • The hadal zone is found from a depth of around 6,000 to 11,000 metres (20,000 to 36,000 ft), and exists in long but narrow topographic V-shaped depressions.
  • Deep-sea trenches of the hadal depth zone (6-11 km) are hotspots for high microbial activity because they receive an unusually high flux of organic matter, made up of animal carcasses, and sinking algae, originating from the surrounding shallower seabeds.
  • Conditions in the hadalpelagic zone are extreme. No sunlight penetrates, the temperature is a constant 4°C, and the pressure is 60–110 MPa.
Hadalpelagic Zone

India’s Deep Ocean Mission

  • Union Ministry of Earth Sciences, Government of India has also launched a ‘Deep Ocean Mission’ for exploration of polymetallic nodules in Central Indian Ocean Basin.
    • Polymetallic nodules contain multiple metals like copper, nickel, cobalt, manganese, iron, lead, zinc, aluminum, silver, gold, and platinum etc. in variable constitutions and are precipitate of hot fluids from upwelling hot magma from the deep interior of the oceanic crust.
    • Of these, cobalt, copper, and nickel are of much importance and in great demand in India as cobalt is used extensively in medical treatment and nickel in batteries.
    • It will reduce India’s dependence on imports of cobalt and other rare earth metals.

Important Trenches of the World (Deepest oceanic trenches)

Aleutian TrenchSouth of the Aleutian Islands, west of Alaska
Bougainville TrenchSouth of New Guinea
Cayman TrenchWestern Caribbean
Cedros Trench (inactive)Pacific coast of Baja California
Hikurangi TrenchEast of New Zealand
Hjort TrenchSouthwest of New Zealand
Izu–Ogasawara TrenchNear Izu and Bonin islands
Japan TrenchEast of Japan
Kermadec TrenchNortheast of New Zealand
Kuril–Kamchatka TrenchNear Kuril islands
Manila TrenchWest of Luzon, Philippines
Mariana TrenchWestern Pacific Ocean; east of Mariana Islands
Middle America TrenchEastern Pacific Ocean; off coast of Mexico, Guatemala, El Salvador, Nicaragua, Costa Rica
New Hebrides TrenchWest of Vanuatu (New Hebrides Islands).
Peru–Chile TrenchEastern Pacific Ocean; off the coast of Peru & Chile
Philippine TrenchEast of the Philippines
Puerto Rico TrenchThe boundary of the Caribbean and Atlantic ocean
Puysegur trenchSouthwest of New Zealand
Ryukyu TrenchEastern edge of Japan’s Ryukyu Islands
South Sandwich TrenchEast of the South Sandwich Islands
Sunda TrenchCurves from south of Java to west of Sumatra and the Andaman and Nicobar Islands
Tonga TrenchNear Tonga
Yap TrenchWestern Pacific Ocean; between Palau Islands and Mariana Trench

important trenches of the world
TrenchOceanLowest Point
Mariana TrenchPacific OceanChallenger Deep
Tonga TrenchPacific OceanHorizon Deep
Philippine TrenchPacific OceanEmden Deep
New Britain TrenchPacific Ocean (Solomon Sea)Planet Deep
Puerto Rico TrenchAtlantic OceanBrownson Deep
South Sandwich TrenchAtlantic OceanMeteor Deep
Peru–Chile Trench or Atacama TrenchPacific OceanRichards Deep
important trenches of the world UPSC

Deepest Ocean trenches in the World [List]

TrenchMaximum Depth
Mariana Trench10,920 m (35,830 ft)
Tonga Trench10,820 m (35,500 ft)
Philippine Trench10,540 m (34,580 ft)
Kuril–Kamchatka Trench10,542 m (34,587 ft)
Kermadec Trench10,047 m (32,963 ft)
Izu–Bonin Trench (Izu–Ogasawara Trench)9,810 m (32,190 ft)
New Britain Trench9,140 m (29,990 ft)
Puerto Rico Trench8,380 m (27,490 ft)
South Sandwich Trench8,265 m (27,116 ft)
Peru–Chile Trench or Atacama Trench8,055 m (26,427 ft)
Japan Trench8,412 m (27,598 ft)
oceanic trenches in the world upsc

Mariana Trench

  • Mariana Trench is located in the western Pacific Ocean, the Marina Trench is considered to be the deepest part of the Earth’s surface. In fact, it is the Challenger Deep in the Mariana Trench that is known as the deepest point.
  • Appears as a crescent-shaped scar, the trench measures around 2,550 km long, 69 km wide on average and has a maximum depth of 10.91 km at the Challenger Deep. At the same time, some other efforts measured the deepest portion at 11.034 km.
  • The deep holes in the Mariana trench were formed due to the collision of converging plates of the oceanic lithosphere.
Mariana Trench

Tonga Trench

  • Located in the southwest Pacific Ocean and at the Kermadec Tonga Subduction Zone’s northern end, the Tonga Trench lies around 10.882 km below sea level. The deepest point in the Tonga trench, known as the Horizon Deep, is considered to be the second deepest point on earth after the Challenger Deep and the deepest trench of the Southern Hemisphere.
  • Stretches at a distance of 2,500 km from New Zealand’s North Island northeast to the island of Tonga, the Tonga trench was formed due to the subduction of the Pacific plate by the Tonga plate.
Kermadec Trench

Philippine Trench

  • The third deepest point in the world, the Galathea Depth in the Philippine trench is 10.54 km below sea level. Also known as Mindanao Trench, this submarine trench is located in the Philippine Sea, spreads in a length of 1,320km and 30km width in the east of the Philippines.
  • Prominent among other trenches in the Philippine Sea, this trench was formed due to a collision between the Eurasian Plate and the smaller Philippine plate. The other major trenches in the Philippine sea include Manila Trench East Luzon Trench, Negros Trench, Sulu Trench, and Cotabato Trench.

Kuril- Kamchatka Trench

  • Another deepest part of the ocean belonging to the Pacific Ocean, this trench lies at a considerable depth of 10.5 km below sea level. Lying close to Kuril Island and off the coast of Kamchatka, this trench is responsible for a number of oceans bed volcanic activities in the region.
  • The trench was formed due to the subduction zone that was developed in the late Cretaceous, which created the Kuril island and the Kamchatka volcanic arcs.

Kermadec Trench

  • Another submarine trench lies on the floor of the South Pacific Ocean, the Kermadec Trench stretches around 1,000 km between the Louisville Seamount Chain and the Hikurangi Plateau.
  • Formed by the subduction of the Pacific plate under the Indo-Australian Plate, the Kermadec Trench has a maximum depth of 1o.04 km.
Kermadec Trench

Izu-Ogasawara Trench

  • Located in the western Pacific Ocean, the Izu-Ogasawara Trench has a maximum depth of 9.78km. Also known as Izu-Bonin Trench, this deep trench stretches from Japan to the northern section of the Mariana Trench and it is also an extension of the Japan Trench.
  • Apart from the Izu-Ogasawara Trench, the western Pacific Ocean houses the Izu Trench and the Bonin Trench.
Izu-Ogasawara Trench

Japan Trench

  • Another deep submarine trench located east of the Japanese islands, the Japan trench is part of the Pacific Ring of Fire in the northern Pacific Ocean.
  • With a maximum depth of 9 km, the Japan trench stretches from the Kuril Islands to the Bonin Islands and is also the extension of the Kuril-Kamchatka Trench and the Izu – Ogasawara Trench to the north and south respectively.
  • The trench was formed due to the subduction of the oceanic Pacific plate beneath the continental Okhotsk Plate. And, it’s the tsunamis and earthquakes that lead to the movement on the subduction zone with the Japan Trench.
Japan Trench

Puerto Rico Trench

  • Located between the Caribbean Sea and the Atlantic Ocean, the Puerto Rico trench marks the deepest point in this region and the eighth deepest point found on the earth’s surface.
  • Lies at a depth of 8.64 km, spotted at Milwaukee Deep, and measures a length of over 800 km, this trench has been responsible for many tragic tsunamis and earthquake activities in this region.
Puerto Rico Trench

South Sandwich Trench

  • The deepest trench in the Atlantic Ocean after Puerto Rico Trench, South Sandwich Trench is at a depth of about 8.42 km, described as Meteor Deep, and runs for over 956 km, making it one of the most noticeable trenches of the world.
  • Located 100 km to the east of the South Sandwich Islands in the southern Atlantic Ocean, this trench was formed by the subduction of the South American Plate’s southernmost portion beneath the small South Sandwich Plate.
  • This South Sandwich Trench is also associated with an active volcanic arc.
South Sandwich Trench

Peru–Chile Trench

  • The Peru–Chile Trench (the Atacama Trench) is located around 160 km off the coast of Peru and Chile in the eastern Pacific Ocean.
  • The Atacama Trench has a maximum depth of 8.06 km below sea level. The deepest point of the trench is known as Richards Deep.
  • The Atacama Trench was formed as a result of a convergent boundary, between the subducting Nazca and the South American Plates.
Peru–Chile Trench
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Tarique habibi

Thank you to concise

Sagar Sharma

Sir you are doing great job…