San Andreas Fault in California – the boundary between the Pacific and North American tectonic plates (image: Leohotens)
There are 15 major tectonic plates which cover the majority of planet Earth’s landmass, and oceanic surface.
They all move gradually – between 21mm & 75mm per year – and will all disappear completely at some point, but by then we will hopefully have some new continents to inhabit, with new plates having appeared.
The World’s tectonic plates are comprised of the Earth’s crust, a mysterious layer called the ‘moho’, and a small bit of the upper mantle.
• List of Major Tectonic Plates
• Map of Major Tectonic Plates
• Map of Earthquake Epicenters (1963-1998)
• What are Tectonic Plates?
• What is the Crust Made From?
• Map Showing the Estimated Thickness of the World’s Crust
List of Major Tectonic Plates in The World
|Primary Tectonic Plates||Secondary Tectonic Plates|
|African Plate||Arabian Plate|
|Antarctic Plate||Caribbean Plate|
|Australian Plate||Cocos Plate|
|Eurasian Plate||Juan de Fuca Plate|
|Indian Plate||Nazca Plate|
|North American Plate||Philippine Sea Plate|
|Pacific Plate||Scotia Plate|
|South American Plate|
There are 8 primary plates on the planet (or 7 if you count the Indo-Australian Plate as a single plate), and they comprise of the majority of the World’s continents’ landmass, along with most of the surface area of the World’s Ocean’s.
The secondary plates are smaller in size than the primary plates, and they do not cover any substantial landmass, apart from the Arabian Plate.
There are a further group of smaller plates, often called tertiary plates, which are the disappearing remains of much larger ancient plates that are now on the edges of our major plates, plus some micro-plates, many of whom will be widely-considered as a part of a primary or secondary plate on maps and in scientific publications.
Map of Major Tectonic Plates in The World
The MAP above – depicting all of the primary and secondary tectonic plates on Earth – was sourced via United States Geological Survey (USGS), an official US government department.
Map of Earthquake Epicenters in The World – 358,214 Events Recorded Between 1963 & 1998
The MAP above – depicting all of the Earthquake epicenters around the World between 1963 and 1998 – was sourced via The DTAM project, a NASA department, which may or may not still exist.
What are Tectonic Plates?
The tectonic plates are a series of plates which cover the entire surface of planet Earth. They can have a depth of up to an estimated 100 km, and are comprised of the entire planets crust, most of the moho, and a tiny piece of the upper mantle. This collective area of rocky planets is generally called the ‘lithosphere’.
The term ‘tectonic plates’ has been historically used by scientists to describe the movement of the lithosphere, however, nowadays the term ‘tectonic plates’ is most widely-used for describing the physical plates themselves, rather than their movement.
The top layer of the tectonic plates – the crust – is continually moving gradually, just like a slow conveyor belt, with new crust appearing on one side of each plate, and disappearing into another boundary it shares with a neighbouring plate.
NOTE* The moho – also know as the ‘Mohorovičić discontinuity’ – is a layer of unknown composition which planet Earth’s crust physically rests upon. It is situated about 5-10 km below the ocean floor and 20-90 km beneath continents. The overall estimated average thickness of the moho is thought to be about 35 km.
What is the Crust Made From?
The upper layer of the tectonic plates – the crust – was produced by substances which have flowed from the inside of our planet. Oceanic crust consists mainly of basaltic rocks which are rich in magnesium, iron and some silicates, with lower density granitic rocks dominating continental crusts, which are enriched in mostly lighter elements, including oxygen, aluminium, sodium, silicon, and potassium.
Due to the recycling nature of the tectonic plate movement, the oldest ocean crust is though to be about 200 millions years old, and the oldest continental crust is believed to be about four billion years old.
Map Showing the Estimated Thickness of the World’s Crust (km)
The MAP above – depicting the estimated thickness of the Earth’s crust – was sourced via United States Geological Survey (USGS), an official US government department.