Mariana Trench
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The Mariana Trench (or Marianas Trench) is the deepest known submarine trench, and the deepest location in the Earth's crust itself. It is located in the floor of the western North Pacific Ocean, to the east of the Mariana Islands at , near Guam.
Description
The trench is the boundary where two tectonic plates meet, a subduction zone where the Pacific Plate is being subducted under the Philippine Plate. The bottom of the trench (Challenger Deep) is farther below sea level than Mount Everest is above it. The trench has a maximum depth of 10,911 meters (35,798 ft) below sea level. Taking into account its latitude and the Earth's equatorial bulge, this puts it at 6,366.4 kilometers (3955.9 mi) from the centre of the Earth. The Arctic Ocean, on the other hand, is about 4,500 meters (14,800 ft) deep, which would put its floor at 6,353 kilometers (3947 mi) from the Earth's center, some 13 kilometers (8.5 mi) closer.Exploration
The trench was first surveyed in 1951 by the Royal Navy vessel Challenger II, which gave its name to the deepest part of the trench, the Challenger Deep. Using echo sounding, the Challenger II measured a depth of 5,960 fathoms (10,900 m, 35,760 ft) at . This sounding was repeatedly made using earphones to hear the return of the signal as the stylus passed across the graduated depth scale, whilst the timing of the speed of the echo-sounding machine, a necessary part of the process, was made with a handheld stopwatch. For these reasons it was considered prudent to subtract one scale division (of 20 fathoms) when officially reporting a new greatest depth of 5,940 fathoms (10,863 m).In 1957, the Russian vessel Vityaz reported a depth of 11,034 meters (36,201 ft), dubbed the Mariana Hollow; this measurement has never been replicated and is not considered accurate. In 1962, the M.V. Spencer F. Baird recorded a greatest depth of 10,915 meters (35,810 ft). In 1984, the Japanese sent the Takuyo, a highly specialized survey vessel out to the Mariana Trench and collected data using a narrow, multi-beam echo sounder; they reported a maximum depth of 11,040.4 meters[1] (this is also reported as 10,920±10 meters).[2] The most accurate measurement on record was taken by another Japanese probe, Kaiko, on March 24, 1995: 10,911 meters (35,798 ft) [3].
In an unprecedented dive, the United States Navy bathyscaphe Trieste reached the bottom at 1:06 p.m. on January 23, 1960, with U.S. Navy Leuitenant Don Walsh and Jacques Piccard on board. Iron shot was used for ballast, with gasoline for buoyancy. The onboard systems indicated a depth of 11,521 meters (37,800 ft), but this was later revised to 10,916 meters (35,813 ft). At the bottom, Walsh and Piccard were surprised to discover soles or flounder about 30 cm (1 ft) long, as well as shrimp. According to Piccard, "The bottom appeared light and clear, a waste of firm diatomaceous ooze".
At the bottom of the Mariana Trench, water exerts a pressure of 1,086 bar (108.6 MPa or 15,751 psi), over 1,000 times the standard atmospheric pressure at sea level.
In Fiction
- In the motion picture The Core, the Mariana Trench is chosen as the entry point for the Journey to the center of the earth.
- In Voyage to the Bottom of the Sea, the 400 ft supersub USOS Seaview is pursued into the Trench to a depth of 3200 feet, before a following sub implodes.
See also
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