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.
The Aleutian Trench, extending 2,900 kilometers from the Gulf of Alaska to Kamchatka, marks the place where the Pacific plate is being subducted beneath the North American plate .
The Aleutian Trench is part of a subducting zone in the Pacific Ocean connecting Alaska to Kamchatka. The trench is formed where the Pacific plate is being subducted under the North American plate. The model projects the Pacific plate forming around 190 Myr ago and the Aleutian Trench forming around 40 Myr ago.
Of the Earth’s 20 major trenches , 17 are found in the Pacific basin, a vast area rimmed by trenches of both marginal and island arc varieties. Marginal trenches bound the west coast of Central and South America from the Gulf of California to southern Chile.
The Mariana Trench is part of a global network of deep troughs that cut across the ocean floor. They form when two tectonic plates collide. At the collision point, one of the plates dives beneath the other into the Earth’s mantle, creating an ocean trench .
In the Pacific Ocean , somewhere between Guam and the Philippines, lies the Marianas Trench, also known as the Mariana Trench . At 35,814 feet below sea level, its bottom is called the Challenger Deep — the deepest point known on Earth.
The subduction along the trench gives rise to the Aleutian Arc , a volcanic island arc , where it runs through the open sea west of the Alaska Peninsula. As a convergent plate boundary, the trench forms part of the boundary between two tectonic plates.
In its northward creep, the Pacific tectonic plate rubs against the North American plate, giving rise to the famous San Andreas and Denali strike-slip faults. In southwestern Alaska, those two plates meet head on, and the Pacific plate sinks beneath the North American plate.
Earthquakes are commonplace throughout much of Alaska . These quakes occur as a result of stresses caused by movements of tectonic plates that make up the Earth’s outer shell.
approximately 36,200 feet
The Five Deeps Expedition was the first to reach the deepest point in each of the Earth’s five oceans: the Puerto Rico Trench in the Atlantic, South Sandwich Trench in the Southern Ocean, Java Trench in the Indian Ocean, Challenger Deep in the Pacific and Molloy Deep in the Arctic.
Websites like Wikipedia complicate matters further, for example, the entry for the Diamantina Fracture Zone refers to it as a Trench and states it is not the deepest place in the Indian Ocean (7079 m) but directs the reader to the ‘ Diamantina Deep ‘, apparently located within the Diamantina Fracture Zone and states it