CLEP Natural Sciences Test Prep / Course / Chapter

Causes of Tectonic Plate Movement

Lesson Transcript
Instructor: Peter Jaeger

Pete currently teaches middle school Science, college level introductory Science, and has a master's degree in Environmental Education.

Tectonic plates are huge moving pieces of the Earth's crust and there are different mechanisms that can explain the causes of their movement. Learn about the different forces and mechanisms involved in the plate movement process, including thermal convection, ridge push, slab pull, and trench suction. Updated: 06/06/2022

Background on Plate Movement

Do you ever wonder if the thing someone just told you is true? For instance, you may have heard that person declare that at some point in the near future, California is going to break off and fall into the ocean. My older brother told me that the Golden State is hanging off the end of the continent and will fall into the Pacific Ocean during the next big earthquake. Do the tectonic plates, or giant pieces of the Earth's crust that fit together and move around on the Earth's surface, really move? If so, what causes them to move? The best stories are often based on fact, so it is helpful to know what is real versus what is not. Yes, tectonic plates move, and the mechanism that causes them to move is the subject of this lesson.

The part of my brother's story that is true is that the Western part of California, west of the San Andreas Fault, is moving in a different direction than the rest of the continent. The Western part of California is moving northwest at the rate of several centimeters per year. Looking to the future, California will indeed one day separate from the rest of North America and become an island. Where I think my brother got confused is the mechanism that will cause this to occur.

Tectonic plates move around and can cause earthquakes and volcanic eruptions.
Tectonic Plates Image

First of all, it is important to know that the Earth's crust is broken up into large pieces called tectonic plates. Remember, tectonic plates are giant pieces of the Earth's crust that fit together and move around on the Earth's surface. This movement can be observed and measured using GPS systems, and the edges of the plates can be detected, as their edges can be seen. We also know that these plates move around with respect to one another. Earthquakes and volcanoes are the results of such plate movement. One question geologists have been trying to answer is: what is causing the plates of the Earth to move? This can be a challenging question because we are not able to get into the Earth's interior to observe it. There are several mechanisms that scientists have developed based on the observations of the plates and a deeper understanding of the inner layers of the Earth. These mechanisms operate at different points in the Earth and very well could complement each other, each assisting in moving the plate in its own fashion.

An error occurred trying to load this video.

Try refreshing the page, or contact customer support.

Coming up next: Plate Boundaries: Convergent, Divergent, and Transform Boundaries

You're on a roll. Keep up the good work!

Take Quiz Watch Next Lesson
Your next lesson will play in 10 seconds
  • 0:05 Background on Plate Movement
  • 2:23 Thermal Convection
  • 4:09 Ridge Push
  • 4:40 Slab Pull
  • 5:21 Trench Suction
  • 6:04 Lesson Summary
Save Timeline
Speed Speed

Thermal Convection

Scientists believe that one of the primary forces behind plate movement is thermal convection. Thermal convection is when heat from the core of the Earth is transferred to the surface of the Earth by the mantle. The mantle is the thick, mostly solid layer of the Earth between the crust and the core. Thermal convection works a lot like a pot of boiling water, which can be seen in this animation.

In convection, heat from the stove warms up the water closest to the stove, causing the water to expand and rise. Cooler water near the surface of the pot sinks to take the place of the rising water. In doing so, a current of water is set up flowing toward the surface and back down again. Using this model, the stove is like the core and the water is the liquid mantle that rotates. The plates on the Earth's surface would be floating on top of the water. These currents push the plates along according to the direction of flow. Geologists think that this same phenomenon is what is happening inside the Earth. Liquid rock near the mantle is heated and rises toward the crust. The rock near the surface is cooler and sinks back down toward the core. This forms the same type of convection current that causes the plates to move. Scientists believe that this cycle of magma rising from the core to the crust and back again takes thousands of years to complete.

Convection currents in the liquid mantle cause the plates to move.
Thermal Convection Current

At the top of the mantle, the rock encounters the thin crust, and, as it pushes it aside, lava flows out from the mantle to form new oceanic crust. As this happens, the plates smash into each other, slide past each other or are pushed under another plate. This movement of the plate along with the upwelling of the mantle by the convection currents may also cause secondary actions that assist in plate movement.

To unlock this lesson you must be a Member.
Create your account

Register to view this lesson

Are you a student or a teacher?

Unlock Your Education

See for yourself why 30 million people use

Become a member and start learning now.
Become a Member  Back

Resources created by teachers for teachers

Over 30,000 video lessons & teaching resources‐all in one place.
Video lessons
Quizzes & Worksheets
Classroom Integration
Lesson Plans

I would definitely recommend to my colleagues. It’s like a teacher waved a magic wand and did the work for me. I feel like it’s a lifeline.

Jennifer B.
Jennifer B.
Create an account to start this course today
Used by over 30 million students worldwide
Create an account