How many tectonic plates does the Earth have?

The number of tectonic plates on Earth ranges from 10 to 100, and most of them don't even appear on official maps.

Large and small tectonic plates on the Earth's surface. Photo: iStock

Billions of years ago, the Earth’s surface was a sea of ​​molten rock. As magma cooled, it formed a continuous crust of rock, with denser minerals accumulating near the center of the planet and less dense minerals rising to the surface. That’s how tectonic plates form at the Earth’s surface, says Catherine Rychert, a geophysicist at the Woods Hole Oceanographic Institution in Massachusetts. A tectonic plate is a layer of crust with a little mantle underneath. Beneath it is weaker, hotter, and more mobile material. The difference in density between the two layers causes the layers above to move, collide, merge, and crash into each other. In these areas, faults and mountains form, volcanoes and earthquakes lead to the birth of life.

The number of tectonic plates covering the Earth's surface ranges from a dozen to nearly 100, depending on the classification criteria. Most researchers agree that there are 12 to 14 major tectonic plates that cover most of the Earth's surface, according to Saskia Goes, a geologist at Imperial College London. Each plate covers at least 20 million square kilometers, with the largest being the North American, African, Eurasian, Indo-Australian, South American, Antarctic, and Pacific plates. The most massive of these is the Pacific plate, which covers 103.3 million square kilometers, followed by the North American plate, which covers 75.9 million square kilometers.

According to Goes, in addition to the seven major tectonic plates, there are five smaller plates: the Philippine Sea, Cocos, Nazca, Arabian, and Juan de Fuca. Some geologists consider the Anatolian Plate (part of the larger Eurasian Plate) and the East African Plate (part of the African Plate) as separate entities because they move at different speeds than the main plate. That is why the number of major tectonic plates ranges from 12 to 14.

The situation gets more complicated when you consider tectonic plate boundaries, where they divide into smaller plates called microplates. Microplates are areas less than a million square kilometers in size. Some scientists estimate there are as many as 57 microplates on Earth. But they are not often shown on world maps. “The number of microplates is constantly changing, depending on how scientists define them differently and how the plate boundaries deform,” Goes explains.

The shifting tectonic plates of the Earth create some remarkable formations. The Pacific Plate may be the fastest, moving northwest at 7-10 cm/year. Its rapid motion is a result of the surrounding subduction zone, also known as the Ring of Fire, where gravity pulls the plates toward the center of the Earth.

An Khang (According to Live Science )

Source link: https://vnexpress.net/trai-dat-co-bao-nhieu-mang-kien-tao-4664249.html