They are the gigantic blocks that make up the solid outer layer of our planet, supporting the continents and oceans. Driven by the movement of the incandescent magma inside the Earth, the ten main plates push each other, move away from each other and sink a few millimeters a year, changing their dimensions and modifying the contour of the terrestrial relief. These gigantic fragments act as artists who recreate the Earth’s landscape. In fact, the word tectonics comes from tektoniké, a Greek expression that means “the art of building”. “But it is more correct to call these structures lithospheric plates, since they extend across the entire outer layer of the planet, the so-called lithosphere”, says geophysicist Eder Cassola Molina, from the University of São Paulo (USP).
The lithosphere is about 150 kilometers thick, a pittance compared to the 6,371 kilometers needed to reach the center of the planet. Each time the huge plates meet, a large amount of energy, equivalent to thousands of atomic bombs, is accumulated in their rocks. From time to time, the arsenal is released explosively, through earthquakes that shake the globe – usually, on the edges of the plates. At the limits of the blocks that support the oceans, the underground bump can give rise to volcanoes, when mountains of molten rock take advantage of the cracks to climb between the plates.
PACIFIC PLATE
The largest oceanic plate – about 70 million square kilometers – is constantly being renewed in the Hawaii region, where magma rises and creates volcanic islands. When meeting the Philippine plate, the plate sinks into a region known as the Mariana Trench, where the ocean reaches its maximum depth: 11,034 meters
NAZCA PLATE
Each year, this 10-million-square-kilometer plate in the eastern Pacific Ocean gets 10 centimeters smaller as it collides with the South American plate. This, being lighter, slides over the Nazca plate, generating volcanoes and raising the Andes mountains more
SOUTH AMERICAN PLATE
As Brazil is right in the middle of this block of 32 million square kilometers, it feels little the effects of earthquakes and volcanoes. At the center of the continent, the plate measures 200 kilometers thick. At the edge of the Africa plate, the youngest lands are no more than 15 kilometers
NORTH AMERICA AND CARIBBEAN PLATE
Covering 70 million square kilometers, it encompasses all of North and Central America. The horizontal displacement in relation to the Pacific plate creates a turbulent boundary: at one of its limits, in California, is the San Andreas fault, famous for devastating earthquakes
AFRICA PLATE
In the middle of the Atlantic, a submerged fault opens the way for magma from the lower mantle, causing this block to progressively move away from the South American plate – with which it formed a single continent 135 million years ago – and grow in size. The trend is to pass the current 65 million square kilometers
ANTARCTICA PLATE
The eastern part of the plate, which 200 million years ago was joined by Australia, Africa and India, collided with at least five smaller plates that formed the western side. The result is a block that supports Antarctica and part of the South Atlantic, covering a total of 25 million square kilometers.
INDO-AUSTRALIAN PLATE
The 45 million square kilometer block that supports India, Australia, New Zealand and most of the Indian Ocean is rapidly heading north. In addition to the Indian subcontinent colliding with Asia, the northeast edge hits the Philippine plate, creating new islands in the turbulent region.
WEST EUROASIAN PLATE
It supports Europe, part of Asia, the North Atlantic and the Mediterranean Sea. In the clash with the Indo-Australian plate, the set of Himalayan mountains was born, in South Asia, where there are more than 100 mountains with altitudes greater than 7 thousand meters. Its total area is 60 million square kilometers
EASTERN EUROASIAN PLATE
In its eastward movement, this block of 40 million square kilometers collides with the Philippine plate and the Pacific plate, in the region where Japan is located. The triple encounter is tumultuous and gives rise to one of the areas of the globe with the highest rate of earthquakes and volcanoes
PHILIPPINES PLATE
This small plate of only 7 million square kilometers concentrates in its limits almost half of the active volcanoes on the planet. Collisions with the East Eurasian Plate cause earthquakes and destructive eruptions, such as Mount Pinatubo in 1991, considered one of the most violent in the last 50 years.