Coordinates: 11°21′N 142°12′E / 11.350°N 142.200°E /
Location of the Mariana Trench
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.
At the bottom of the trench the water column above exerts a pressure
of 1,086 bars (15,750 psi), more than 1,000 times the standard
atmospheric pressure at sea level. At this pressure, the density of
water is increased by 4.96%, so that 95 litres of water under the
pressure of the
Challenger Deep would contain the same mass as 100
litres at the surface. The temperature at the top is 1 to 4 °C
(34 to 39 °F).
The trench is not the part of the seafloor closest to the center of
the Earth. This is because the
Earth is not a perfect sphere; its
radius is about 25 kilometres (16 mi) less at the poles than at
the equator. As a result, parts of the Arctic
Ocean seabed are at
least 13 kilometres (8.1 mi) closer to the
Earth's center than
Challenger Deep seafloor.
Xenophyophores have been found in the trench by Scripps Institution of
Oceanography researchers at a record depth of 10.6 kilometres
(6.6 mi) below the sea surface. On 17 March 2013, researchers
Scottish Association for Marine Science reported data that
suggested microbial life forms thrive within the trench.
3.2 Planned descents
5 Possible nuclear waste disposal site
6 See also
8 External links
Mariana Trench is named for the nearby
Mariana Islands (in turn
named Las Marianas in honor of Spanish Queen Mariana of Austria, widow
of Philip IV of Spain). The islands are part of the island arc that is
formed on an over-riding plate, called the
Mariana Plate (also named
for the islands), on the western side of the trench.
The Pacific plate is subducted beneath the Mariana Plate, creating the
Mariana trench, and (further on) the arc of the Mariana islands, as
water trapped in the plate is released and explodes upward to form
island volcanoes and earthquakes .
Mariana Trench is part of the Izu-Bonin-Mariana subduction system
that forms the boundary between two tectonic plates. In this system,
the western edge of one plate, the Pacific Plate, is subducted (i.e.,
thrust) beneath the smaller
Mariana Plate that lies to the west.
Crustal material at the western edge of the
Pacific Plate is some of
the oldest oceanic crust on earth (up to 170 million years old), and
is therefore cooler and more dense; hence its great height difference
relative to the higher-riding (and younger) Mariana Plate. The deepest
area at the plate boundary is the
Mariana Trench proper.
The movement of the Pacific and Mariana plates is also indirectly
responsible for the formation of the Mariana Islands. These volcanic
islands are caused by
Flux melting of the upper mantle due to release
of water that is trapped in minerals of the subducted portion of the
See also: Challenger Deep
The trench was first sounded during the
Challenger expedition in 1875,
using a weighted rope, which recorded a depth of 4,475 fathoms (8,184
metres; 26,850 feet). In 1877, a map was published called
Tiefenkarte des Grossen Ozeans ("Deep map of the Great Ocean") by
Petermann, which showed a Challenger Tief ("Challenger deep") at the
location of that sounding. In 1899, USS Nero, a converted collier,
recorded a depth of 5,269 fathoms (9,636 metres; 31,614 feet).
In 1951, Challenger II surveyed the trench using echo sounding, a much
more precise and vastly easier way to measure depth than the sounding
equipment and drag lines used in the original expedition. During this
survey, the deepest part of the trench was recorded when the
Challenger II measured a depth of 5,960 fathoms (10,900 metres; 35,760
feet) at 11°19′N 142°15′E / 11.317°N 142.250°E /
11.317; 142.250, known as the Challenger Deep.
In 1957, the Soviet vessel Vityaz reported a depth of 11,034 metres
(36,201 ft) at a location dubbed the Mariana Hollow.
In 1962, the surface ship M.V. Spencer F. Baird recorded a maximum
depth of 10,915 metres (35,810 ft) using precision depth gauges.
In 1984, the Japanese survey vessel Takuyō (拓洋) collected data
Mariana Trench using a narrow, multi-beam echo sounder; it
reported a maximum depth of 10,924 metres (35,840 ft), also
reported as 10,920 metres (35,830 ft) ±10 m
(33 ft). Remotely Operated Vehicle KAIKO reached the deepest
area of the
Mariana Trench and made the deepest diving record of
10,911 metres (35,797 ft) on March 24, 1995.
During surveys carried out between 1997 and 2001, a spot was found
Mariana Trench that had depth similar to that of the
Challenger Deep, possibly even deeper. It was discovered while
scientists from the Hawaii Institute of Geophysics and Planetology
were completing a survey around Guam; they used a sonar mapping system
towed behind the research ship to conduct the survey. This new spot
was named the HMRG (Hawaii Mapping Research Group) Deep, after the
group of scientists who discovered it.
On 1 June 2009, sonar mapping of the
Challenger Deep by the Simrad
EM120 sonar multibeam bathymetry system for deep water, mapping aboard
RV Kilo Moana
RV Kilo Moana (mothership of the Nereus vehicle), indicated a spot
with a depth of 10,971 metres (35,994 ft). The sonar system uses
phase and amplitude bottom detection, with an accuracy of better than
0.2% of water depth across the entire swath (implying that the depth
figure is accurate to ± 22 metres (72 ft)).
In 2011, it was announced at the
American Geophysical Union
American Geophysical Union Fall
Meeting that a US Navy hydrographic ship equipped with a multibeam
echosounder conducted a survey which mapped the entire trench to 100
metres (330 ft) resolution. The mapping revealed the existence
of four rocky outcrops thought to be former seamounts.
Mariana Trench is a site chosen by researchers at Washington
University and the
Woods Hole Oceanographic Institution
Woods Hole Oceanographic Institution in 2012 for a
seismic survey to investigate the subsurface water cycle. Using both
ocean-bottom seismometers and hydrophones the scientists are able to
map structures as deep as 97 kilometres (60 mi) beneath the
The bathyscaphe Trieste (designed by Auguste Piccard), the first
manned vehicle to reach the bottom of the Mariana Trench.
Four descents have been achieved. The first was the manned descent by
Swiss-designed, Italian-built, United States Navy-owned bathyscaphe
Trieste which reached the bottom at 1:06 pm on 23 January 1960,
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 m (37,799 ft), but this was later
revised to 10,916 m (35,814 ft). The depth was estimated from
a conversion of pressure measured and calculations based on the water
density from sea surface to seabed.
This was followed by the unmanned ROVs
Kaikō in 1996 and Nereus in
2009. The first three expeditions directly measured very similar
depths of 10,902 to 10,916 m (35,768 to 35,814 ft). The
fourth was made by Canadian film director
James Cameron in 2012. On 26
March, he reached the bottom of the
Mariana Trench in the submersible
vessel Deepsea Challenger.
In July 2015, members of the National Oceanic and Atmospheric
Administration, Oregon State University, and the Coast Guard submerged
a hydrophone into the deepest part of the Mariana Trench, the
Challenger Deep, never having deployed one past a mile. The
titanium-shelled hydrophone was designed to withstand the immense
pressure 7 miles under. Although researchers were unable to
retrieve the hydrophone until November, the data capacity was full
within the first 23 days. After months of analyzing the sounds, the
experts were surprised to pick up natural and man-made sounds such as
boats, earthquakes, a typhoon, and baleen whales. Due to the
mission's success, the researchers announced plans to deploy a second
hydrophone in 2017 for an extended period of time.
As of February 2012[update], at least two other teams are
planning piloted submarines to reach the bottom of the Mariana Trench.
Triton Submarines, a Florida-based company that designs and
manufactures private submarines, plans for a crew of three to take 120
minutes to reach the seabed. DOER Marine, a marine technology
company based near
San Francisco and set up in 1992, plans for a crew
of two or three to take 90 minutes to reach the seabed.
The expedition conducted in 1960 claimed to have observed, with great
surprise because of the high pressure, large creatures living at the
bottom, such as a flatfish about 30 cm (12 in) long, and
shrimp. According to Piccard, "The bottom appeared light and
clear, a waste of firm diatomaceous ooze". Many marine biologists
are now skeptical of the supposed sighting of the flatfish, and it is
suggested that the creature may instead have been a sea
cucumber. During the second expedition, the unmanned vehicle
Kaikō collected mud samples from the seabed. Tiny organisms were
found to be living in those samples.
In July 2011, a research expedition deployed untethered landers,
called dropcams, equipped with digital video and lights to explore
this region of the deep sea. Amongst many other living organisms, some
gigantic single-celled amoebas with a size of more than 10 cm
(4 in), belonging to the class of xenophyophores were
observed. Xenophyophores are noteworthy for their size, their
extreme abundance on the seafloor and their role as hosts for a
variety of organisms.
In December 2014, a new species of snailfish was discovered at a depth
of 8,145 m (26,722 ft), breaking the previous record for the
deepest living fish seen on video.
During the 2014 expedition, several new species were filmed including
huge crustaceans known as supergiants.
Deep-sea gigantism is the
process where species grow larger than their shallow water
In May 2017 an unidentified type of snailfish was filmed at a depth of
8,178 metres (26,800 ft).
In 2016, a research expedition looked at the chemical makeup of
crustacean scavengers collected from a range of 7,841–10,250 metres
within the trench. Within these organisms, the researchers found
extremely elevated concentrations of PCBs, a chemical toxin banned for
its environmental harm in the 1970s, concentrated at all depths within
the sediment of the trench.
Possible nuclear waste disposal site
Like other oceanic trenches, the
Mariana Trench has been proposed 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, the second layer of the
Earth. However, ocean dumping of nuclear waste is prohibited by
international law. Furthermore, plate subduction zones are
associated with very large megathrust earthquakes, the effects of
which are unpredictable for the safety of long-term disposal of
nuclear wastes within the hadopelagic ecosystem.
Marianas Trench Marine National Monument, United States national
monument at the trench. This National Monument protects 95,216 square
miles (246,610 km2) of submerged lands and waters of the Mariana
Archipelago. It includes some of the Mariana Trench, but not the
deepest part, the Challenger Deep, which lies just outside the
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Wikimedia Commons has media related to Mariana Trench.
Mariana Trench Dive (25 March 2012) – Deepsea Challenger.
Mariana Trench Dive (23 January 1960) – Trieste (Newsreel).
Mariana Trench Dive (50th Anniv) – Trieste – Capt Don Walsh.
Mariana Trench – Maps (Google).
Ocean Explorer (Ofc
Ocean Exploration & Rsch).
Ocean Explorer – Multimedia – Mariana Arc (podcast).
Ocean Explorer – Video Playlist – Ring of Fire
Tectonic plates of
East Asia (Eurasian Plate-
Pacific Plate Convergence
Philippine Sea Plate
Philippine Mobile Belt
Faults and rift zones
Baikal Rift Zone
Itoigawa-Shizuoka Tectonic Line
Japan Median Tectonic Line
Northeastern Japan Arc
Philippine Fault System
Trenches and troughs
East Luzon Trench
Boso Triple Junction