There are somewhere from twelve to almost one hundred of them, and the
majority aren't even marked on official maps.
The surface of the Earth was a sea of molten rock billions of years ago.
This boiling lava produced a continuous, stony shell as it cooled, the
less-dense minerals ascending to the surface and the heavier particles
consolidating into the planet's center.
According to
Catherine Rychert, a geophysicist at the Woods Hole Oceanographic Institution in
Massachusetts, "that is how the plates formed at the surface of the Earth,"
Live Science said. "The plate is the crust, then a bit of the mantle beneath
it …. Beneath that you have weaker material."
This inferior substance is more mobile and heated. The overlaying plates
are able to move, rubbing against, diverging from, and colliding with one
another because to the strength gradient between these layers. Rifts and
mountains occur in these zones, and earthquakes and volcanoes erupt.
How many plates, though, are there on Earth's surface? Depending on how you
look at it, the answer might be anything from a dozen to over hundred.
The majority of geologists concur that the majority of Earth's surface is
made up of 12–14 "primary" plates, according to
Saskia Goes, an Imperial College London geophysicist. Each plate has a minimum extent
of 7.7 million square miles (20 million square kilometers), with the African, Eurasian, Indo-Australian, South American, Antarctic,
and Pacific plates having the biggest areas. With a total area of 39.9
million square miles (103.3 million square kilometers), the Pacific Plate is
the largest of them. It is closely followed by the North American Plate,
which has a total area of 29.3 million square miles (74.9 million square
kilometers).
"In addition to the seven very large [plates], there are five more somewhat
smaller ones: Philippine Sea, Cocos, Nazca, Arabian and the Juan de Fuca,"
Goes stated to Live Science. Because they "are moving at speeds that are
clearly different from these main plates," some geologists classify the East
African Plate, which is a portion of the African Plate, and the Anatolian
Plate, which is a portion of the larger Eurasian Plate, as distinct
entities. This explains the range of 12 to 14 in the main plate
estimate.
When you examine plate boundaries—the places where plate tectonics causes
plates to split into smaller chunks known as microplates—things get much
more difficult. There are around
57
of them
on Earth, according to some experts, and their combined area is less than
386,000 square miles (1 million square kilometers). However, they are typically absent from globe maps, a difference that may
be related to some degree of ambiguity surrounding their formation.
"The number of microplates will keep on changing, depending on how
different scientists choose to define them, and as we learn more about how
and where the deformation at plate boundaries localizes," Goes stated.
Earth's shifting plates produce some intriguing situations as geologists
try to solve this dynamic conundrum. According to Rychert, the Pacific Plate
is most likely moving the quickest, shifting northwest by 2.8 to 3.9 inches
(7 to 10 cm) year.
"Gravity is pulling the plates down into the Earth from a surrounding ring
of subduction zones, also known as the Ring of Fire," she explained, adding
that the continuous action may even be swallowing continents. "We think that
sometimes continents founder, and a piece will actually fall off into the
mantle," Rychert stated.
What the plate-encrusted surface of our planet will look like after a few
billion years is still unknown due to these enormous forces at work.
