Why does the Atlantic Ocean expand while the Pacific Ocean shrinks? | Science

The Atlantic Ocean is expanding by about two inches each year, pushing Europe and Africa away from the Americas, while the Pacific Ocean is shrinking by a fifth of a square mile per year.

Although the size of the Earth’s oceans does not change significantly in the short term, any changes have a significant effect over millions of years due to the geological processes that occur. But it is the set of interactions that continue to shape our world.

The change in the size of the oceans is an important factor, the tectonic plates that make up the earth’s crust, because the earth’s surface is divided into many tectonic plates that are constantly moving, although we are not usually aware of them.

Tectonic plates can move toward each other, away from each other, or next to each other. As the plates move away from each other, they create what is called a ridge or oceanic rift, and as they move towards each other, this can lead to the formation of a subduction zone beneath one plate beneath the other.

Why is the Atlantic Ocean expanding?

As for the Atlantic Ocean, it is a vast body of water on our planet that covers more than 20% of the Earth’s surface. Although it is the second largest ocean in the world and has an area of ​​106.5 million square kilometers, it is still expanding at a rate of 4 centimeters every year.

That’s because parts of the Atlantic Ocean are moving away from each other, and the key to this expansion lies in what’s happening beneath a large underwater mountain range in the middle, according to a study published in 2021 in the journal Nature. of the ocean known as the Mid-Atlantic Ridge.

University of Southampton researchers have shown that material deep in the Earth rises to the surface under the Mid-Atlantic Ridge, forming a new oceanic crust, as magma rises from the Earth’s crust and solidifies at the surface, pushing the plates.

The Mid-Atlantic Ridge is the largest tectonic range on the planet, as it stretches 16.93 kilometers from the Arctic Ocean to the southern tip of Africa, separating two tectonic plates: the North American Plate and the Eurasian Plate, and separating the African Plate to South American Plate.

According to Live Science, the Mid-Atlantic Ridge is where the South American and North American plates are moving away from the Eurasian and African plates at a rate of about 4 centimeters per year, widening the Atlantic Ocean.

According to information published on the University of Southampton website, the research team found that magma and rocks can travel up to 410 miles below the crust to the surface. It is this flow of material that propels tectonic plates and continents upward at a rate of 4 centimeters per year.

The study found that the Mid-Atlantic Ridge is a hotspot for convection, which makes the region thinner and magma material rises to the ocean floor more easily than the rest of Earth.

Material trying to move from the lower to upper mantle is usually blocked by a dense group of rocks called the mantle transition zone, located between 255 miles and 410 miles below our feet. Research suggests that the upwelling of material from deep in the mantle may be driving this expansion in the Atlantic Ocean.

The process began 200 million years ago, but one day the rate of expansion may accelerate, Catherine Reichert, a geophysicist at the University of Southampton and co-author of the study, tells Insider.

Why is the Pacific Ocean shrinking?

As for the Pacific Ocean, although it is the world’s largest ocean covering about 30% of the Earth’s surface, it is shrinking by about a fifth of a square mile every year, some scientists believe. After millions of years, it will disappear completely.

As reported on the “Science ABC” website, this contraction is caused by Earth’s largest tectonic plate, the Pacific plate, being pushed beneath other plates in a process called subduction. The Pacific plate is subducting as it moves deeper into the Earth’s crust, causing the ocean above it to shrink.

In addition, the Pacific Ocean experiences complex interactions between different convergent and divergent tectonic plate boundaries and eventually shrinks in size. While parts of the Pacific Plate are moving toward other plates, such as the North American Plate and the Philippine Sea Plate, there are also areas where plates are moving away from other plates, such as the eastern boundary of the Pacific Plate with the Nazca Plate.

In addition to having many volcanoes in the world, it is believed that most earthquakes occur in the Pacific Ocean. All these cause high vibrations, causing the plates to move and destroy old parts of the Earth’s crust. The sea floor cannot grow fast enough to replace degraded areas.

Ultimately, the size of Earth’s oceans is determined by long-term geologic processes related to plate tectonics, and any changes in ocean sizes occur on geologic timescales, not human lifetimes. These geological processes have been shaping the world as we know it for millions of years.

300 million years ago, our planet did not consist of 7 continents, but instead consisted of one ocean and one continent, which scientists called “Pangaea”. Over time, the continent slowly collapsed, according to Bright Side.

At one point, South America, Antarctica, Australia, and Africa were one unit, and North America and Eurasia were another. Over time, these continents also separated, each moving in its own direction.