View the map of Tectonic Plates of the world shown below, Earth's tectonic plates are large slabs of the Earth's lithosphere that move over the semi-fluid asthenosphere beneath. There are seven major plates, including the Pacific Plate, North American Plate, and Eurasian Plate, and several smaller ones. These plates shift due to convection currents in the mantle, causing geological activity such as earthquakes, volcanic eruptions, and the formation of mountain ranges. The boundaries where plates interact—such as the San Andreas Fault in California—are zones of significant seismic activity. The plates move at an average rate of 1 to 2 inches per year.
Explore world plates map to see what tectonic name lies where and its distrubution around countries and continents.
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List of Tectonic Plates of the Earth
Plate Name
Type
Approximate Size (Million km²)
Notable Boundaries
Key Features
Pacific Plate
Oceanic
103
Ring of Fire, San Andreas Fault (with North American Plate)
Largest tectonic plate, covers most of the Pacific Ocean
North American Plate
Continental & Oceanic
75.9
San Andreas Fault (with Pacific Plate), Mid-Atlantic Ridge
Covers North America, Greenland, and part of the Atlantic Ocean
Eurasian Plate
Continental & Oceanic
67.8
Himalayan Boundary (with Indian Plate), Mid-Atlantic Ridge
Covers Europe, Asia, and part of the Atlantic Ocean
African Plate
Continental & Oceanic
61.3
East African Rift, Mid-Atlantic Ridge
Includes the continent of Africa and surrounding oceanic crust
Antarctic Plate
Continental & Oceanic
60.9
Convergent boundaries with Pacific, South American, and Australian Plates
Surrounds Antarctica, covered in ice
Indo-Australian Plate
Continental & Oceanic
58.9
Himalayas (collision with Eurasian Plate), Java Trench
Includes India, Australia, and surrounding oceanic crust
South American Plate
Continental & Oceanic
43.6
Andes Mountains (with Nazca Plate), Mid-Atlantic Ridge
Covers South America and part of the Atlantic Ocean
Arabian Plate
Continental
5
East African Rift, Zagros Mountains (collision with Eurasian Plate)
Includes the Arabian Peninsula
Caribbean Plate
Oceanic
3.2
Boundary with North American and South American Plates
Covers the Caribbean Sea and surrounding areas
Scotia Plate
Oceanic
1.6
Between South American and Antarctic Plates
Located south of South America
Philippine Sea Plate
Oceanic
5.5
Boundaries with Pacific Plate, Eurasian Plate
Associated with numerous subduction zones and volcanic activity
Cocos Plate
Oceanic
2.9
Subduction beneath the North American Plate, Central America
Located off the western coast of Central America
Nazca Plate
Oceanic
15.6
Subduction beneath the South American Plate, forming the Andes
Located off the western coast of South America
Indian Plate
Continental & Oceanic
11
Convergent boundary with Eurasian Plate, forming the Himalayas
Part of the Indo-Australian Plate, but often considered separately
Earth's Tectonic Plates
The Earth’s surface is composed of several rigid sections known as tectonic plates. These massive plates form the Earth's lithosphere and move over the more fluid asthenosphere beneath. The interaction of tectonic plates is responsible for shaping the Earth’s surface and creating significant geological features like mountains, ocean trenches, and volcanic activity. Understanding tectonic plates is essential for comprehending the dynamic nature of our planet and the forces that shape it.
Structure and Composition of Tectonic Plates
Tectonic plates are made of two types of crust: continental crust and oceanic crust. These plates vary in thickness and composition, which affects their density and how they interact with each other.
1. Continental Crust
The continental crust is thicker, ranging from 20 to 70 kilometers, and is composed mainly of light granitic rocks. It forms the continents and major landmasses. Due to its lower density, it "floats" higher on the mantle compared to the oceanic crust.
2. Oceanic Crust
The oceanic crust is thinner but denser, typically ranging from 5 to 10 kilometers thick. It is made primarily of basaltic rock, which is heavier than the granitic rock found in continental crust. Oceanic crust forms the ocean floors and is continually recycled at subduction zones.
Major Tectonic Plates
There are seven major tectonic plates that dominate the Earth's surface:
1. Pacific Plate
The Pacific Plate is the largest tectonic plate, covering much of the Pacific Ocean. It is predominantly oceanic and is constantly expanding due to seafloor spreading at divergent boundaries.
2. North American Plate
The North American Plate includes North America, parts of the Atlantic Ocean, and extends into the Arctic region. It interacts with several other plates, creating seismic activity along fault lines like the San Andreas Fault.
3. Eurasian Plate
The Eurasian Plate covers Europe and Asia, stretching from the Atlantic Ocean to the Pacific Ocean. This plate is primarily continental and is responsible for the formation of the Himalayas due to its collision with the Indian Plate.
4. African Plate
The African Plate contains the African continent and surrounding oceanic crust. It is notable for its divergent boundary with the South American Plate, where seafloor spreading occurs in the Atlantic Ocean.
5. Antarctic Plate
The Antarctic Plate covers the continent of Antarctica and extends outward into the surrounding oceans. It is mostly a passive plate with limited tectonic activity, although it is involved in seafloor spreading along the Southern Ocean ridges.
6. Indo-Australian Plate
The Indo-Australian Plate includes Australia, India, and parts of the Indian Ocean. This plate is moving northward and colliding with the Eurasian Plate, contributing to the uplift of the Himalayas.
7. South American Plate
The South American Plate covers South America and part of the Atlantic Ocean. Its interaction with the African Plate is responsible for the Atlantic Ocean’s widening. The Andes mountain range is formed by the subduction of the oceanic Nazca Plate beneath this plate.
Types of Plate Boundaries
The boundaries where tectonic plates interact are classified into three main types:
1. Divergent Boundaries
At divergent boundaries, tectonic plates move apart from each other. This process occurs mostly in oceanic regions, where magma from the mantle rises to create new oceanic crust. The **Mid-Atlantic Ridge** is an example of a divergent boundary, where the Eurasian Plate and North American Plate are moving apart.
2. Convergent Boundaries
At convergent boundaries, tectonic plates collide, and one plate is often forced beneath the other in a process called subduction. Subduction zones lead to the formation of deep ocean trenches, volcanic arcs, and mountain ranges. The collision between the Indian Plate and Eurasian Plate has created the Himalayas, the highest mountain range on Earth.
3. Transform Boundaries
At transform boundaries, plates slide horizontally past each other. This type of boundary is associated with earthquakes, as the plates grind against each other. The **San Andreas Fault** in California is a famous example of a transform boundary, where the Pacific Plate moves northward relative to the North American Plate.
Driving Forces Behind Plate Movement
Tectonic plates are constantly in motion due to several forces within the Earth:
1. Mantle Convection
The heat from the Earth’s core generates mantle convection currents. These currents move through the semi-fluid asthenosphere, causing the lithosphere above it to shift. This is the primary driving force behind the movement of tectonic plates.
2. Slab Pull
At subduction zones, the weight of the descending oceanic plate pulls the rest of the plate along with it. This process, known as slab pull, is one of the most significant contributors to plate movement.
3. Ridge Push
Newly formed oceanic crust at divergent boundaries is elevated because it is hot and buoyant. As it cools, it becomes denser and slides away from the ridge, pushing the tectonic plate ahead. This is referred to as ridge push.
Geological Activity Associated with Tectonic Plates
The movement of tectonic plates results in a variety of geological phenomena:
1. Earthquakes
Most **earthquakes** occur along tectonic plate boundaries, where plates either collide, move apart, or slide past one another. The sudden release of energy caused by this movement generates seismic waves that result in ground shaking. Areas around the **Pacific Ring of Fire** are particularly prone to earthquakes due to the numerous plate boundaries in the region.
2. Volcanic Activity
Volcanoes commonly form at convergent boundaries, where one tectonic plate subducts beneath another. The descending plate melts as it is forced into the mantle, creating magma that rises to the surface to form volcanoes. The **Cascade Range** in the United States and **Mount Fuji** in Japan are examples of volcanic activity resulting from subduction.
3. Mountain Building
When two continental plates converge, the land between them is forced upwards, creating **mountain ranges**. The collision between the Indian Plate and Eurasian Plate continues to push the Himalayas to greater heights each year.
