The outermost layer of the earth's crust is silicate minerals, which are between 6 km and 30-50 km thick. Below the crust is a mantle, and between the mantle and the crust is a Moho fault surface. The mantle is 2,850 km thick and consists of two parts, the upper and lower parts, and the upper part of the mantle has a asthenosphere. Below the mantle, the center of the earth, and between the core and mantle, the Gutenberg fault surface. The earth's core is divided into an outer core and an inner core, the outer core is liquid, the inner core is solid, and the inner core is liquid.
Above the asthenosphere, above the crust and the cooler, harder mantle, is called the lithosphere.
The surface, or lithosphere, is a plate about 100 to 150 kilometers thick, divided into the Pacific Plate, the Indian Ocean Plate, the Eurasian Plate, the African Plate, the American Plate, and the Antarctic Plate.
The continental plate, on the other hand, is relatively thin because of its lower density. The opposite is true of the ocean plate, which weighs less because of its high density.
Under the action of thermal convection, the mantle layer formed by the viscous fluid will move, and this movement in turn drives the plate movement. Different plates can squeeze each other, bump into each other, or diverge.
At the junction of the Eurasian plate and the Pacific plate, the movement of the mantle will make the two squeeze and collide with each other, but the density of the Pacific plate is greater than that of the Eurasian plate, so the edge of the Pacific plate sinks when impacted, so a huge arc-shaped trench about 70 kilometers and about 2550 kilometers long is formed at the junction of the two plates, that is, the Mariana Trench.
At 8848.86 meters above sea level, Mount Everest is the world's highest peak, also known as the "Ridge of the World", Mount Everest is located at the bottom of the Mariana Trench, and its summit will not be able to surface. In fact, the deepest depth of the Mariana Trench is more than 11,000 meters.
In the ocean, every 10 meters increase in water depth increases the pressure by 1 atmosphere, and the deepest pressure in the Mariana Trench can reach 1100 atmospheres. At such atmospheric pressure, 1 can be carried per square centimeter. 1 ton. In the Mariana Trench, except for the extremely high air pressure, the bottom of the sea is dark and there is no trace of light. The average temperature here is only 2 degrees Celsius, almost freezing.
Due to the harsh environment, scientists have encountered difficulties in scientific exploration in the Mariana Trench. It wasn't until January 1960 that scientists first dived to the bottom of the Mariana Trench to conduct a field survey.
Is there life in the Mariana Trench in such a harsh natural environment?
Scientists have found that more than 2,000 meters below sea level, there are many species of marine life, including common fish, shrimp, octopus, sharks and whales. At 2000-3000 meters underwater, there is a largemouth anglerfish.
At a depth of more than 4,000 meters, the sea water in the Mariana Trench has become more gloomy and more stressful, the number of various marine organisms is constantly declining, and even the bones have begun to become crystal clear.
At a depth of more than 8,000 meters, scientists speculate that this is already a "forbidden area for life". But in 2004, scientists found a lionfish in the area, breaking the record for depth of habitat in the Mariana Trench. The lion is 25 to 40 cm long , has a yellow body , and has 13 stingers on its back, usually at a depth of 300 m.
The Chinese oceanographic research vessel Science discovered 10 colorful coral forests on a moll south of the Mariana Trench in 2019. This forest is full of corals and pillar star moths, like an "underwater garden", which is very rare.
Scientists have also found a lot of carbon in the Mariana Trench, suggesting that the trench plays a more important role in adjusting Earth's environment than previously understood. Scientists believe the Mariana Trench could serve as a giant carbon dioxide harvesting device that can continuously absorb carbon dioxide. Scientists estimate that the microbes in the Mariana Trench produce more than 6,000 meters of carbon from the seabed.
Wiens, a professor of earth and planetary sciences at Washington University in St. Louis, published a report in 2012 in which they surveyed the underwater conditions of the Mariana Trench using seafloor seismometers and hydrophones, and finally found that the Mariana Trench was swallowing up seawater at an alarming rate.
The Vins team also estimates that the Mariana Trench consumes three billion tons of seawater a year. This means that the Mariana Trench has consumed 3,000 megatons of seawater in the past million years.
How could the Mariana Trench swallow the ocean so wildly?
The reason for this has to start from the structure of the earth's crust. As the Pacific Plate subducts down and becomes embedded in the asthenosphere, the part of the Eurasian Plate bordering the Pacific Plate creates a "wound", causing a large amount of seawater to flow into the ground from here.
The Mariana Trench has consumed 3,000 megatons of seawater in the past million years, so why is sea level rising instead of falling?
We all know the surface water cycle, but in reality, the water cycle also exists deep underground. Although a large amount of seawater is sucked up to the earth, after a volcanic eruption, this water vapor is evaporated, returned to the atmosphere, and returned to the sea. In addition, water erupting from the ground also flows into the sea. Therefore, in this cycle of repeated cycles, the sea water does not actually decrease much, so the sea level will not decrease.
And the rise in sea level is also due to global warming. In the past few decades, global warming has intensified, causing glaciers in the Antarctic and Arctic regions to gradually melt, causing sea levels to rise. Scientists estimate that if all the glaciers melted, the global sea level would rise by 60-70 meters.