What are the 7 major tectonic plates?

The Pacific, African, Antarctic, North American, Eurasian, Australian (or Indo-Australian) and South American plates. The Pacific Plate is by far the largest, at about 104.6 million square kilometers, roughly 20.5% of Earth's surface.

What is the smallest tectonic plate?

In the PB2002 model the smallest plate is the Manus Plate in the Bismarck Sea north of Papua New Guinea, with an area of about 8,200 square kilometers. Other models may not count it as a separate plate at all.

Why do scientists disagree on the number of plates?

Some boundaries are not sharp lines but broad zones where the crust deforms gradually. Whether a small block inside such a zone counts as its own plate depends on how precisely its motion can be measured. Models built for different purposes draw these lines differently.

Is the Indo-Australian Plate one plate or two?

Older textbooks treat it as a single Indo-Australian Plate. Measurements of plate motion show that India and Australia move slightly differently, so PB2002 and many modern models split them into the Indian Plate and the Australian Plate, joined by a broad zone of deformation in the central Indian Ocean.

How Many Tectonic Plates Are There? (7 Major, 52 Total)

Q: How many tectonic plates are there?

There are seven major plates, which together cover about 81% of Earth's surface, plus a number of minor plates and microplates. The PB2002 model used on this site defines 52 plates in total. Other models give different totals because they divide small and deforming regions in different ways.

The short answer

There are seven major tectonic plates, about a dozen commonly named minor plates and a long list of microplates. The exact total depends on which model you use. The PB2002 model, published by the geophysicist Peter Bird in 2003 and used for every map on this site, counts 52 plates.

Grouped by size on this site, 7 plates are major, 13 are minor (over 1 million km² each) and 32 are microplates. Bird’s paper itself splits them into 14 large and 38 small plates. The 7 major plates cover about 81% of Earth’s surface, the minor plates about 17%, and the 32 microplates only about 2% between them.

The 7 major plates, by area

Areas below come from the PB2002 plate outlines and include both land and seafloor.

Pacific Plate: about 104.6 million km², 20.5% of Earth’s surface. It is almost all ocean floor and is nearly twice the size of the next largest plate.
African Plate: about 58.5 million km², 11.5%. PB2002 counts the eastern part of Africa separately as the Somali Plate.
Antarctic Plate: about 58.2 million km², 11.4%. It carries Antarctica and is almost completely surrounded by spreading ridges and transform faults.
North American Plate: about 55.4 million km², 10.9%. It reaches from the Mid-Atlantic Ridge to eastern Siberia.
Eurasian Plate: about 48.6 million km², 9.5%. It carries Europe and much of Asia.
Australian Plate: about 46.0 million km², 9.0%. Many textbooks merge it with the Indian Plate as the Indo-Australian Plate.
South American Plate: about 41.8 million km², 8.2%. It carries South America and the western half of the South Atlantic.

The main minor plates

The 13 minor plates in PB2002 range from about 19 million km² down to about 1.5 million km². Listed by area, they are the Somali, Nazca, Indian, Sunda, Philippine Sea, Amur, Arabian, Okhotsk, Caribbean, Cocos, Yangtze, Scotia and Caroline plates.

The Somali Plate is the largest, at about 19.2 million km², and the Nazca Plate is next, at about 16.1 million km². Several minor plates are well established because they have clear boundaries all around: the Nazca and Cocos plates, for example, are bounded by spreading ridges and trenches. Others, including the Okhotsk, Amur, Yangtze, Sunda and Somali plates, are still debated, because parts of their edges are slow or diffuse.

The 32 microplates

The rest of PB2002’s 52 plates are microplates, each smaller than about 1 million km². The largest are the North Andes Plate, the Altiplano Plate and the Banda Sea Plate. The smallest is the Manus Plate in the Bismarck Sea, at about 8,200 km², followed by the Galapagos Plate at about 14,600 km².

Microplates cluster where plate boundaries are complex. More than a dozen sit in the south-west Pacific and eastern Indonesia, between the converging Pacific and Australian plates. Others mark the meeting points of spreading ridges, such as the Easter and Juan Fernandez plates on the East Pacific Rise, or blocks squeezed sideways by collisions, such as the Anatolian Plate in Turkey.

Why plate counts differ

Microplates

A microplate counts as a plate only if its motion can be told apart from its neighbors’. As GPS networks and seafloor surveys improve, researchers can resolve smaller blocks, and the count goes up. A model built for a global overview may leave them out.

Diffuse boundaries

On continents and in some ocean basins, deformation spreads across wide zones instead of a single line. Bird marked the largest of these zones in PB2002 as orogens, regions where the 52-plate picture is a simplification. Drawing one plate or several inside such a zone is a judgment call.

The Indo-Australian question

The best known example is the Indian and Australian plates. They were long treated as one Indo-Australian Plate. Plate motion data later showed that they rotate slightly relative to each other, with the boundary between them spread across a wide part of the central Indian Ocean. PB2002 splits them, which is why it lists the Australian Plate as major and the Indian Plate as minor. Together they would cover about 58.4 million km², close to the African and Antarctic plates.

The same logic applies elsewhere. Combining PB2002’s African and Somali plates would give an African Plate of about 77.6 million km². Other global models use different totals, such as MORVEL with 25 plates, and none of these numbers is wrong. They reflect different choices about where to draw the lines.

Browse all 52 plates, with their areas, neighbors and speeds, in the plate directory, or see where they meet on the plate boundaries page.

How Many Tectonic Plates Are There?