10 things you probably didn't know about the deepest ocean in the world

With outstanding scientific advances, it is hoped that in the near future, humans can solve all the mysteries of the hadal sea.

We always think that the ocean is a deep place, and that's really true. Scientists now divide the waters with depths greater than 200m into the 'deep sea' section .

However, the average depth of the entire ocean is about 3,500 meters. And the deepest point on the ocean floor called the 'Challenger Deep' is located in the Mariana Trench in the western Pacific Ocean, where the depth is over 11,000m.

Image of Mariana fissure.

Scientists classify the depth of the sea into four levels:

1. From the sea surface to a depth of 0.2 km, it is called the "littoral zone".
2. From a depth of 0.2-3km, it is called a 'bathyal zone'.
3. From a depth of 36km, it is called an "abyssal zone".
4. If the depth exceeds the region of the 'deep', this place will be called the hadal region.

The hadal region is mainly composed of deep furrows due to the fact that the tectonic plates are encroached and collapsed, forming vast places with a depth of more than 11,000m. There are still animals living and thriving here, but most of them are blind because their habitat almost does not exist light.

1. Kingdom of Hades

The phrase 'hadal' is related to Hades, the Greek god of hell, who is the brother of Zeus and the sea god Poseidon. This term means "the abode of the dead".

In myth, Hades forbade his inhabitants to travel to other worlds and at the same time the creatures of the outside could not penetrate his kingdom.

This is true if the case of marine life. Because of the pressure, the body of each species can only adapt to a certain depth. They cannot surpass the limits set by their bodies. Otherwise, serious disorders will occur and they will quickly die.

In the hadal region, the terrible pressure of less than 11,000m of seawater has made this place a truly inviolable region. No creature on the upper level can penetrate this place, nor can all the residents living here ever reach the higher floors.

2. How deep is the sea?

The immense depth of the undersea tectonic grooves was explored by the method of analyzing the explosive sound of a bomb.

Specifically, the scientists will drive the ship to a deep sea, then they will throw a block of TNT weighing half a pound into the sea and simultaneously detonating. The sound of the bomb will be recorded and analyzed to calculate the depth of the sea floor.

This method has been used to explore the depth of different tectonic grooves. However, the depth of the hadal region in the Mariana Trench remains a mystery. Scientists can only estimate this trench to a depth exceeding 11,000m.

Around the world, scientists have discovered four other tectonic trenches deeper than 10,000m, including Tonga, Kuril-Kamchatka, Philippine, and Kermadec.

3. Who discovered the hadal region?

The HMS Challenger expedition from 1873 to 1876 was the first mission to study the depths of the hadal region. HMS collected sediments with a depth of about 8,000m.

However, scientists at the time argued quite fiercely about whether the samples collected were real sediments or if the carcasses decomposed from higher levels fell.

In 1901, Mission Princess Alice successfully explored and obtained specimens from a depth of more than 6,000.

By 1948, an Swedish scientist's expedition had found a number of animals that lived between 7,000 and 8,000 meters deep in the Puerto Rican tectonic trench. This proves that organisms can survive at depths greater than 6,000m.

In 1956, the first images of the hadal region were taken by renowned biologist Jacques Cousteau while studying in the Atlantic.

4. How wide was the area?

Most hadal regions were formed 65.5 million years ago.

The hadal region consists of a series of discrete tectonic grooves and irregular subsidence points. There are a total of 46 hadal regions worldwide, including 33 trenches and 13 deep plaques.

The average depth of tectonic grooves is 8,216m. The total area of ​​the hadal region accounts for only about 0.2% of the total seafloor area but accounts for 45% of the total depth of the sea.

Of the 33 trenches that have reached the depth of hadal, 26 are located in the Pacific Ocean, 3 in the Atlantic Ocean, 2 in the Indian Ocean and 2 in the Southern Ocean. Most of the trenches are located in the western Pacific Ocean.

Scientists believe that most hadal regions were formed 65.5 million years ago during the Cenozoic period.

5. The hadal region is an important factor for the appearance of humans

The Earth appears to be the only planet with subduction zones and tectonic plates that are still active. The tectonic plates on Mercury and the Moon are dead. Mars has long stopped construction activities. Venus is dominated by a thick layer of lithosphere with agglomerated manti patches.

On Earth, it is thanks to subduction zones that continental crust is created and protrudes from the ocean.

Therefore, if there were no subduction zones and hadal regions, until now, all areas on the ground would still be submerged. Humans will never be able to appear.

6. What is the environment like in the hadal region?

The temperature in the waters of the seabed is extremely cold, ranging from 1 ° C to 4 ° C. However, every 10 meters deep, the hydrostatic pressure will increase by 1atm (atmosphere - the unit of pressure). Therefore, the pressure in the hadal region will range from 600 to 1,100atm. The pressure at the deepest point will equal the weight of up to 1 ton being placed at your finger tip.

7. What creatures exist there?

Quite a few sea creatures have been found in the seafloor that reach the hadal depth. The most common groups of organisms are polychaete worms, bivalve sheaths, abdominal legs, bivalve crustaceans and sea cucumbers.

These species often colonize and are relatively widely distributed. Contrary to popular belief, the hadal region does not contain monstrous giants or aliens.

8. The terrible secrets that people hide in the hadal region

In the 1970s, Puerto Rico tectonic grooves were a place where people used to treat medical waste. In just over 5 years, more than 387,000 tons of waste has been dumped on this place. This figure is equivalent to the weight of 880 Boeing 747 aircraft.

In addition, people also brought down this place, the ill-fated Apollo 13 spacecraft when it exploded with a thermo-radioactive isotope (RTG) generator.

RTG contained 3.9 kg of plutonium-238 and was eventually dumped into the southwestern Pacific Ocean by the US government. Following the trackers, RTG sank into the Tonga tectonic gulf and lay at a depth of between 6,000 and 9,000m. RTG will continue to create radioactive pollution for a large area of ​​the ocean floor for many more thousand years.

9. A place of continuous earthquake

In 2011, a magnitude Tohoku-Oki earthquake struck off the coast of Japan. The epicenter is located in a tectonic groove deep beneath the sea. The earthquake created a chain tsunami that left 20,000 people dead and missing, causing massive damage to 35 coastal cities. The Tohoku-Oki earthquake caused an additional 666 small aftershocks with magnitude exceeding 5 richter.

In 2004 the Sumatra-Andaman earthquake, which had a epicenter in the Java tecton, released so much energy that it changed the Earth's rotation, shortening the length of a day to 2.68. microseconds. Similarly, the Tohoku-Oki earthquake deviated the earth's axis by 10 cm to 25 cm, shortening the length of the day to 1.8 microseconds.

10. Is the hadal region really deep?

One of the most common quotes among scientists is: ' If Mount Everest is down the Mariana Trench, it will be covered with 2km of water '. This proves the terrible depth of hadal grooves. Conquering these deep points has encountered many difficulties.

However, the distance of 11,000m is not really big. The Mississippi River is 11,000 meters wide at its widest point. Manhattan Island is twice as long as the Mariana Trench. And with the average running speed of Mo Farah at the 2012 Olympics, we can overcome the distance of 11,000m in just 30 minutes.

The only barrier that hadal regions create for humans is pressure . With the advancement of technology, in the near future, we can even open tours to visit the tectonic grooves with absolute safety.

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