The Mariana Trench Is the deepest area of the world's oceans. It is found in the western Pacific Ocean and east of the Mariana Islands.
These islands are part of the trenches that coincide with a subduction zone, a point where two adjacent tectonic plates collide.
The pit is approximately 2,550 kilometers long, with an average width of 69 kilometers. Its maximum depth point is known as the Challenger Chasm, which is estimated at 10,994 meters.
The Marianas grave, located within the territories of the US dependencies of the Northern Mariana Islands and Guam, was designated a US national monument in 2009.
The pit 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 kilometers less at the poles than at the equator. As a result, parts of the bottom of the Arctic Ocean are at least 13 kilometers closer to the center of the Earth than the Abyss Challenger .
You may also like to know What are the oceanic graves? This will allow you to better understand this geological phenomenon.
Characteristics of the Mariana Trench
The Marianas grave is in a perpetual darkness, due to its extreme depth, also counting with temperatures that are to a few degrees above the freezing point.
The relatively warm surface water of the oceans like the Pacific Ocean extends to depths of between 500 and 1,000 feet. Beneath the surface waters, the temperature descends rapidly, forming a layer called Thermocline .
The thermocline varies in thickness from about 1,000 feet to 3,000 feet. Below this point, the water cools more slowly. In areas such as the Mariana Trench, the water temperature ranges from 1-4 degrees Celsius.
The water pressure at the bottom of the trench is a crushing of eight tons per square inch, or about one thousand times the standard atmospheric pressure at sea level. The pressure increases with depth.
Soundings
The Marianas grave and its depths were first probed in 1875 by the British ship H.M.S. Challenger , Being this part of the first global oceanographic cruise.
Scientists recorded a depth of 4,475 fathoms (about five miles, or eight kilometers) using a heavy resonant string.
In November of 1899, the USS Nero, a collarier turned of the navy, probed in 5269 fathoms (9636m). This was the deepest depth observed at that time and a record was kept for several years until the German research vessel Planet probed into the Philippine pit.
Albatross Steamer of the US Fish Commission also probed the Mariana Trench and found 8802m, in February 1900 southeastern Guam. The cable ship Colonia surveyed a route that crossed the north end of the trench in 1902.
Almost thirty years after the first survey indicated extraordinary depths in the vicinity of the Mariana Islands, the trench was finally defined. The German geographer Otto Krummel published what could be the first autonomous map of the trench in the 1907 edition of Handbuch der Ozeanographie .
It would be another forty years before it was recognized that the Mariana trench had the deepest depths of the world ocean.
In 1951, H.M.S. Challenger II inspected the trench by an echo sounding, which is a much more accurate and much easier way to measure depth than the sounding equipment and the drag lines that were 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 meters) at 11 ° 19'N 142 ° 15'E, known as the Challenger Abyss.
The Challenger expedition gave a first glimpse of deep ocean basins and other features of the ocean floor.
In addition to exploring the Mariana trench, the Challenger also compiled important data on the characteristics and species of the Pacific, Atlantic and Indian Oceans, covering nearly 130,000 kilometers, approximately 71,000 nautical miles.
About 5000 new species of sea creatures were discovered during the 4-year expedition.
In March 1995, the unmanned Japanese submarine Kaiko was used to conduct deeper investigations into the Marian Trench.
The Kaiko is a sophisticated vessel with a very precise positioning system, allowing scientists to gather important data without the need to endanger a human diver.
The Marianas moat is a site chosen by researchers at the University of Washington and the Woods Hole Oceanographic Institution in 2012 for seismic research on the groundwater cycle.
Using both seismometers and oceanic hydrophones, scientists are able to map structures as deep as 60 miles below the surface.
Descents
The first time humans descended into the Challenger Chasm was over 50 years ago. On January 23, 1960, the Swiss scientist Jacques Piccard And the lieutenant Don Walsh Of the US Navy achieved this goal.
It was in a submersible of the United States Navy, a bathyscaphe called Trieste, which established a diving record to a depth of 10, 900 meters.
The scientist had the idea of using 70 tons of gasoline to fill the submarine floats 50 feet long, knowing that gasoline was lighter than water, which in turn was used to flood the submersible air tanks, allowing Its descent.
As depth deepened, gasoline compressed, which reduced the buoyancy of the submarine and accelerated its progress until, approximately 5 hours later, the Trieste had reached the bottom of the ocean, supporting more than 16,000 pounds of pressure per square inch .
After two years of modifying and testing dives near San Diego and Guam, the bathyscaphe Trieste was ready for its great dive to the bottom of the Marianas grave.
On January 20, 1960, a command ship, a tugboat, and the bathyscaphe left Guam. The first task of the command ship was to find the deepest part of the Challenger chasm in order to ensure proper boon rights for the explorers.
But because the depth probe on the ship could not measure such extreme depths, the crew employed a crude method. They turned the fuses on TNT And threw them down the side to explode underwater.
Then they used stopwatches to count the seconds until the sound waves of the blast bounced off the distant seabed and backed up to the ship's hydrophone. They soon identified a target area of 1.6 kilometers wide and 11 kilometers long.
After a five-hour descent, the couple spent only about 20 minutes at the bottom and could not take any photos due to clouds of silt Agitated by its passage.
By the late 1960s, the United States Navy had abandoned manned exploration of the world's deepest abysses.
The Trieste team expected to do many deep dives with their vehicle, but the Navy, citing safety concerns, decided to limit the craft to depths above 6000 meters.
Next-generation research submarines built by oceanography institutions around the world were also kept at more shallow depths. By building boats that could reach 6,000 meters, they could explore 98 percent of the ocean, they argued, all but the mysterious trenches.
Oceanographers learned to rely on robotic vehicles to investigate places humans could not go.
On March 26, 2012, film director James Cameron managed to play the bottom of the Marianas graves in the subsea Deepsea Challenger, after a decrease of 2 hours and 36 minutes.
Cameron spent several hours exploring the ocean floor, collecting information and scientific data, and information on specimens before beginning his 70-minute climb.
In July 2015, members of the National Oceanic and Atmospheric Administration, Oregon State University and the Coast Guard dipped a hydrophone in the deepest part of the Mariana trench, Challenger Abyss.
Having never deployed one beyond a mile, the titanium shell hydrophone was designed to withstand the immense pressure 7 miles below. Although the researchers were unable to recover the hydrophone until November, data capacity was complete in the first 23 days.
After months of sound analysis, experts were surprised to pick up the natural and artificial sounds like boats, earthquakes, a typhoon and whale sounds. Due to the success of the mission, researchers announced plans to deploy a second hydrophone in 2017 over an extended period of time.
Ecology
Until the historical immersion of Piccard and Walsh, scientists had debated whether life could exist under such extreme pressure. But at the bottom, Trieste's reflector illuminated a creature Piccard thought was a smooth fish, a moment Piccard would later eagerly describe in a book about his voyage.
The expedition by Piccard and Walsh claimed to have observed (to great surprise due to the high pressure) large creatures that live in the background, like a flat fish about 30 cm long, and shrimp. According to Piccard, the bottom seemed clear and clear.
Many marine biologists are now skeptical about the supposed sighting of flatfish, and it is suggested that the creature could have been a sea cucumber.
During the second expedition, the Kaikō unmanned vehicle collected mud samples from the seabed. It was found that tiny organisms lived in these samples.
Scientists at the Scripps Institution of Oceanography have found giant amebes 10.6 kilometers below the surface of the ocean in the Marian Trench to be exact.
To put that in perspective: these amebas, also known as xenophophores, are living in a trench about 1.6 kilometers deeper than the height of Mount Everest. The previous depth record for xenofophores was approximately 7.5 kilometers.
Kevin Hardy, an oceanic engineer at Scripps, who organized the cruise, explained that the Mariana Trench, located east of the Mariana Islands, has been little explored until recently because technology would not allow it.
The pressure at the bottom of the trench is approximately 16,500 pounds per square inch. The pressure at sea level is 14.7 psi.
The pressure at 35,000 feet below sea level is so intense, Hardy said, that human bones would be completely crushed.
To protect the cameras and lights from being crushed, Hardy and his team built a 17-inch diameter sphere, made of 1 inch thick glass. Hardy said that the thickness and strength of the glass allow the sphere to withstand the pressures of the deep sea.
Apart from this, Earth's deepest ocean trench is home to a community of surprisingly active bacteria, suggesting that other trenches may be the meeting points of microbial life, say researchers.
Researchers analyzed levels of oxygen uptake into sediments, revealing the activity of deep-sea microbes.
They found unexpectedly high levels of oxygen consumption from the seabed, indicating a microbial community twice as active as that of a nearby 6,000 m (6,900 m), about 35 km (60 km) south.
Sediments from the Challenger Abyss also had significantly higher levels of microbes and organic compounds than the nearby, higher site.
Researchers suggest that the Mariana trench acts as a natural trap for sediments from above. Similar effects are seen in other submarine guns.
Another group of researchers recently spotted microbial communities thriving in the oceanic crust.
This discovery focused on rocks that measured up to about 1,150 to 1,900 feet (350 to 580 m) below the seafloor. Below about 8,500 feet (2,600 m) of water from the northwest coast of the United States.
These microbes apparently live from the energy of chemical reactions between water and rock instead of nutrients snowing from above.
References
- The Editors of Encyclopædia Britannica. (2017). Mariana Trench. 2017, of Encyclopedia Britannica. Retrieved from: britannica.com.
- Charles Q. Choi. (2013). Thrive Microbes in Deepest Spot on Earth. 2017, by Amazing Planet. Retrieved from: livescience.com.
- Deborah Netburn. (2011). Giant amoeba found in Mariana Trench 6.6 miles beneath the sea. 2017, from L. A. Times Retrieved from: latimesblogs.latimes.com.
- Albert E. Theberge. (2009). Thirty Years of Discovering the Mariana Trench. 2017, Hydro International Retrieved from: hydro-international.com.
- Deepsea Challenge. (2012). The Mariana Trench. 2017, from Deepsea Challenge. Retrieved from: deepseachallenge.com.
- Ker Than. (2012). James Cameron Completes Record-Breaking Mariana Trench Dive. 2017, National Geographic News. Retrieved from: news.nationalgeographic.com.
- Eliza Strickland. (2012). Don Walsh Describes the Trip to the Bottom of the Mariana Trench. 2017, from IEEE Spectrum. Retrieved from: spectrum.ieee.org.