Marianas trench

• The Mariana Trench is the deepest part of the world's oceans. It is located in the western Pacific Ocean, to the east of the Mariana Islands. The trench is about 2,550 kilometres long but has an average width of only 69 kilometres. It also reaches 10.911 km in depth.

What plate boundaries?

• In this system, the western edge of the Pacific plate, is subducted beneath the smaller Philippine Plate. This is because the Pacific plate is the largest of all the tectonic plates on Earth, and is compact and become very dense; hence its great height-difference to the Philippine Plate. This deep area at the plate boundary, is the Mariana Trench .

What type of plate boundaries?• This diagram illustrates the destructive plate boundaries

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Processes involved

• Sometimes a piece of the ocean floor (a plate) will form a crack, and one side of the crack will sink beneath the other side. As the sinking side falls into the Earth’s mantle below, it pulls the rest of its plate with it. The ocean floor deepens along this crack. The sinking sea floor grinds against the other side of the crack and tears pieces off to be carried down into the Earth. The overall result is a long, deep trench that marks the location of the initial crack. These features are called subduction zones or oceanic trenches. This process is how the Mariana Trench formed.

• The Mariana Trench’s inhabitants might even shed light on the emergence of life on Earth. Mud volcanoes located near ocean trenches might have provided the right conditions for our planet’s first life-forms. Additionally, studying rocks from ocean trenches could lead to a better understanding of the earthquakes that create the powerful and devastating tsunamis seen around the Pacific Ring of Fire.

What impact have there been

• Like other oceanic trenches, the Mariana Trench has been put forward as a site for nuclear waste disposal in the hope that tectonic plate subduction occurring at the site might eventually push the nuclear waste deep into the Earth's mantle. However, ocean dumping of nuclear waste is prohibited by international law plate subduction zones are associated with very large earthquakes, the effects of which are unpredictable to the safety of long-term disposal.