The Latin word fodĕre, which can be translated as "dig" , became fossa, which came to our language as pit . This is what is called a cavity or an excavation. Oceanic , meanwhile, is that linked to ocean (the sea that separates the continents and covers much of the surface of our planet).
The idea of Oceanic trench , in this context, refers to a depression of the underwater bottom which is next to the mainland or near the coast of islands of volcanic origin. These sinks may have a depth of more than ten kilometers and present waters with temperatures between 0 ° C and 2 ° C.
He Pacific Ocean It has the largest number of ocean trenches and those with the highest depth . So far, the Mariana Trench It is the deepest ocean trench known. It is located southeast of Mariana Islands , at Northwestern pacific .
The deepest area of the Mariana Trench it is known as chasm Challenger . Along the history several expeditions were made to explore this place: in 2012 the filmmaker James Cameron reached more than 10,898 meters deep in the submersible Deepsea Challenger .
Ocean trenches are generated when two tectonic plates meet and collide, causing the densest to enter under each other. East phenomenon , known as subduction , causes the sinking of the underwater floor: that is, it causes the oceanic pit.
The concept of subduction is within the framework of the Tectonic plates , a theory of geology that serves to explain the way in which the lithosphere is structured, that is, the rigid layer that covers the surface of our planet. This process in which an oceanic zone of one plate sinks below the limit of another, takes place in a large number of subduction zones.
At present, almost all subduction zones are in the so-called Pacific fire belt, although it is also possible to find others in some regions of the Antilles, the Indian coast of Indonesia and the Mediterranean Sea. It is precisely in these areas that ocean trenches are formed, where the convergence and the collision of two lithopheric plates.
If we take the case of the Peru-Chile Trench, also known by the name of Atacama Trench, we are facing a clear example of the consequence of a collision between two plates: the oceanic one of Nazca (a city located to the south of Peru) and the continental one of South America.
In the subduction zones where the ocean trenches are located there is also a considerable seismic activity intensity , which originates because of three phenomena starring the two plates: friction, compression and tension. All this usually begins the tsunamis and earthquakes in Indonesia and Japan, for example.
When the subducted plate reaches the asthenosphere (the upper part of the mantle that is under the lithosphere) melts and in this state ascends to give rise to a volcano . According to the characteristics of each plate, it is possible that the activity gives rise to island arches (a type of archipelago) or that a Mountain range, as are the cases of the Sunda Islands and the Mariana Trench, respectively.
The Tonga Trench , the Japan Trench , the Kuril Trench , the Philippines Trench and the Kermadec Trench they are other ocean graves more than ten kilometers deep. It should be noted that, despite being so deep, in these graves live diverse species .