Oceanic Trench: Definition with List of Trenches and Ocean

Oceanic Trench and Their Location (Ocean)

Oceanic Trench: List | Examples | Location

› In the ocean, there are mountains and valleys just like on land, including an especially deep type of valley called a trench.

› Oceanic trench is a deep section of the ocean usually where an oceanic plate is sinking below a continental plate.

› Continents can tuck under each other just like one piece of paper can tuck under another, in a process called subduction.

› Ocean trenches are natural tectonic plate boundaries between two crustal plates. When a continental plate converges with an oceanic plate a subduction zone forms. The heavier oceanic plate subducts beneath the lighter continental plate forming a trench.

› In subduction, one tectonic plate (a large portion of the earth's crust) slides under another. The plate that is slipping under the other plate bends and forms an ocean trench. The subduction zones where ocean trenches form become long, deep valleys. . . very deep valleys.

› There are many steep-sided canyons and deep, narrow valleys in the bottom of the ocean.

› Ocean trenches are the deepest part of the ocean basin and are deeper than any valley found on land.

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

The Mariana Trench or Marianas Trench is the deepest part of the world's oceans. It is located in the western Pacific Ocean, an average of 200 kilometres (124 mi) to the east of the Mariana Islands, in the Western Pacific East of Philippines. It is a crescent-shaped scar in the Earth's crust, and measures about 2,550 km (1,580 mi) long and 69 km (43 mi) wide on average. It reaches a maximum-known depth of 10,994 metres (36,070 ft) (± 40 metres [130 ft]) at a small slot-shaped valley in its floor known as the Challenger Deep, at its southern end, although some unrepeated measurements place the deepest portion at 11,034 metres (36,201 ft). For comparison: if Mount Everest were dropped into the trench at this point, its peak would still be over 1.6 kilometres (1 mi) underwater. In 2009, Marianas Trench was established as a United States National Monument.

Oceanic trench begins to subduct
Ocean trenches form when a heavier and flexible oceanic plate begins its descent. The seaward side of the trench has a gentle slope of about 5 degrees because the plate must bend as it plunges downward.

Inner wall of the trench
The continental side of most trenches forms the inner wall. The wall has a steeper slope which is usually between 10 and 16 degrees. The two plates slide past each other where they intersect at the bottom of the trench. Most subduction zones are located around the Pacific Ocean.

Volcanic Arcs
Volcanic arcs form above overriding plates in subduction zones. A volcanic arc is a belt of volcanoes that are fueled by the melting subducting plate. The Cascade Volcanoes are a volcanic arc that stretches 700 miles southward from British Columbia to Northern California on the continental side of the Cascadia Subduction Zone.

Aleutian Arc
The Aleutian Arc is a large volcanic arc that has formed as the Pacific Plate subducts beneath the North American Plate. The Aleutian Trench separates the two plates.

List of Deepest oceanic trenches

Trench	Ocean	Maximum Depth
Mariana Trench	Pacific Ocean	11,034 m (36,201 ft)
Tonga Trench	Pacific Ocean	10,882 m (35,702 ft)
Philippine Trench	Pacific Ocean	10,545 m (34,596 ft)
Kuril–Kamchatka Trench	Pacific Ocean	10,542 m (34,587 ft)
Kermadec Trench	Pacific Ocean	10,047 m (32,963 ft)
Izu-Bonin Trench (Izu-Ogasawara Trench)	Pacific Ocean	9,810 m (32,190 ft)
Japan Trench	Pacific Ocean	10,375 m (34,039 ft)
Puerto Rico Trench	Atlantic Ocean	8,800 m (28,900 ft)
South Sandwich Trench	Atlantic Ocean	8,428 m (27,651 ft)
Peru–Chile Trench or Atacama Trench	Pacific Ocean	8,065 m (26,460 ft)

Notable oceanic trenches

Trench	Location
Aleutian Trench	South of the Aleutian Islands, west of Alaska
Bougainville Trench	South of New Guinea
Cayman Trench	Western Caribbean Sea
Cedros Trench (inactive)	Pacific coast of Baja California
Hikurangi Trench	East of New Zealand
Izu-Ogasawara Trench	Near Izu and Bonin islands
Japan Trench	Northeast Japan
Kermadec Trench *	Northeast of New Zealand
Kuril–Kamchatka Trench *	Near Kuril islands
Manila Trench	West of Luzon, Philippines
Mariana Trench *	Western Pacific ocean; east of Mariana Islands
Middle America Trench	Eastern Pacific Ocean; off coast of Mexico, Guatemala, El Salvador, Nicaragua, Costa Rica
New Hebrides Trench	West of Vanuatu (New Hebrides Islands).
Peru–Chile Trench	Eastern Pacific ocean; off coast of Peru & Chile
Philippine Trench *	East of the Philippines
Puerto Rico Trench	Boundary of the Caribbean Sea and Atlantic ocean
Puysegur trench	Southwest of New Zealand
Ryukyu Trench	Eastern edge of Japan's Ryukyu Islands
South Sandwich Trench	East of the South Sandwich Islands
Sunda Trench	Curves from south of Java to west of Sumatra and the Andaman and Nicobar Islands
Tonga Trench *	Near Tonga
Yap Trench	Western Pacific ocean; between Palau Islands and Mariana Trench

(*) The 5 deepest trenches in the world

Ancient oceanic trenches

Trench	Location
Intermontane Trench	Western North America; between the Intermontane Islands and North America
Insular Trench	Western North America; between the Insular Islands and the Intermontane Islands
Farallon Trench	Western North America
Tethyan Trench	South of Turkey, Iran, Tibet and Southeast Asia

What is an example of an ocean trench?

What is the deepest trench in the ocean?

The deepest valley on Earth is an ocean trench called the Challenger Deep, which is part of the Mariana Trench in the Pacific near Guam. The deepest point of the Challenger Deep is 36,070 feet below the ocean surface. That makes it over 13,000 feet deeper than Everest is tall.

How does a deep ocean trench form?

Trenches are formed by subduction, a geophysical process in which two or more of Earth's tectonic plates converge and the older, denser plate is pushed beneath the lighter plate and deep into the mantle, causing the seafloor and outermost crust (the lithosphere) to bend and form a steep, V-shaped depression.

What is the name of the trench in the Atlantic Ocean?

The deepest point in each of the earth's oceans are as follows; the Arctic Ocean's Eurasian Basin at 5,450 meters (17,881 feet) deep, the Indian Ocean's Java Trench at 7,725 meters (25,344 feet) deep, the Atlantic Ocean's Puerto Rico Trench at 8,648 meters (28,374 feet) deep and the Pacific Ocean's Mariana Trench at 11,033 meters (36,201 feet) deep.