However, a study by scientists did reveal such a serious problem. The seismic sensor set by the research team of Washington University in St. Louis in the subduction zone of Mariana Trench shows that the deepest part of the earth is swallowing seawater at a speed 4.5 times higher than that originally estimated by human beings. This speed shocked scientists!
A paper published in Nature by scientists from Washington University in St. Louis.
How fast does the earth swallow seawater into its interior?
In February, the Royal Challenger set out for a marine survey. 1875 In March, Challenger arrived in the Mariana Islands in the western Pacific Ocean and began its 363rd exploration. It is found that the depth here far exceeds the measurement limit of the tethered weight it carries by 8 kilometers. According to the scope of many investigations, an extremely deep area was drawn, and the challenger named it challenger abyss.
Later, after many modern surveys, the ocean survey ship measured the depth here to be about 10900 meters. After the theory of plate movement of the earth matures, we have a deeper understanding of the causes of the Mariana Trench, which was formed by the Pacific plate subducting under the Philippine plate, as shown in the following figure:
Seawater plays an extremely important role in the subduction of this plate because there are several results. First of all, seawater will become a lubricant between plates, making the Pacific plate dive deeper into the earth faster.
Because of this problem, there has also been a big discussion about "Japan's sinking", because the subduction of the Pacific plate to the Eurasian plate also has this problem, and the Pacific plate may accelerate its decline, thus bringing the Japanese mainland into the abyss of the crust!
Another problem is the only way for seawater to enter the earth's interior. The purpose of the research team of Washington University in St. Louis is to investigate the speed of seawater entering the earth's interior, so the team set up several monitoring points in the Mariana Trench to investigate.
The research team found that the speed of seismic waves began to slow down 30 kilometers below the surface. After analysis and research, the research team found the speed at which the trench swallowed water into the interior. According to the assessment, it is concluded that about 3 trillion tons of seawater are swallowed up every million years, with an average of about 3 billion tons per year.
Previously, scientists estimated that the Mariana Trench swallowed up to 654.38+billion tons of seawater every year, which greatly exceeded scientists' expectations. There are about 30 trenches in the world, the main one is 17, and the smaller one is 13. As long as the trench formed in the subduction zone will swallow seawater in this way, which is three times as much as previously estimated. What is this concept?
Why did the earth swallow so much seawater and the sea level didn't drop?
The earth under our feet is just a thin crust of the whole earth, and below it is boiling magma. The upwelling of mantle plume produces new land, and the plate moves under the impetus of these magma and new land. The earth's crust consists of 15 plates, and their movements shape the shape and position of the continent and unique landforms, such as trenches and mountains!
They may have moved since 3.2 billion years ago. Since that day, the movement of subduction zone has swallowed a lot of seawater every day, which has been swallowed for 3.2 billion years! But everyone has a question, why does the ocean seem to have changed little until now? Since the ice age, the ocean has risen slightly, because the ice sheets at the poles are melting.
Why didn't the sea level drop?
Scientists have been worried about sea level rise, because the sea level will rise by 66 meters after the polar ice sheet melts! Obviously, the seawater swallowed by these trenches has not lowered the sea level. Is it too small? Actually, it is not, but because the swallowed seawater will return to the ground through the circulation inside the earth.
There are several most important methods. First, the most direct is the submarine hot spring, which means that the ocean penetrates into the earth's crust and the seawater heated at high temperature inside re-enters the ocean. Hot springs carry a large number of hydrates and dissolved substances in the earth's crust, including sulfides and various metals, forming a unique undersea hot spring ecology.
The other is to re-enter the atmosphere through volcanic eruption, and then return to the ocean through rainfall! When a volcano erupts, it will spit out a lot of volcanic gases, including water vapor, carbon dioxide, sulfur dioxide, nitrogen, argon, helium, organic compounds and other gases, of which water vapor accounts for more than 60%!
Volcanic gas composition
1790, Italian geologist Scipione Breislak collected and analyzed volcanic gas. Water vapor, carbon dioxide and sulfide gas are the earliest components found and analyzed.
Of course, some of them will be preserved in the crust in the form of hydrate for a long time, circulated back to the mantle layer, and then returned to the atmosphere through volcanoes for a long time. This is a dynamic balance. Although the Mariana Trench is devouring seawater, some volcanoes have already paid back the debts owed millions or even hundreds of millions of years ago to the ocean, which is really a long time, but it will always be paid back.
But there is still one thing to remind, a large part of the water on the earth comes from space! 198 1 year, the United States launched a "power exploration 65438 +0" satellite to make physical observations on the earth's atmosphere. American astrophysicist Louis Franck discovered a lot of black spots. Through research, it is known that these spots were originally caused by the water vapor released by comets when they rushed into the upper atmosphere.
It is estimated that tens of thousands of tons of water enter the earth every year, so overall, the earth actually earns a little.