What is the driving mechanism of plate tectonics?

The answer that your science teacher is looking for is probably "mantle convection"...

But if you really want to impress your teacher, you should know that that answer is actually incorrect.

Plates do not ride along on top of convection cells in the mantle like a conveyor belt. It's an outdated concept. That's what Earth scientists used to believe, but now they understand that even though convection does happen in the mantle, the effect of mantle convection on the movement of plates is probably too minor to be able to drive plate tectonics.

The true answer is not "mantle convection,"... but instead, it is a force called "slab pull!"

Slab pull results from the sinking of subducted lithospheric plates at subduction zones. The immense weight of the sinking plate pulls down the rest of the plate as well, causing the whole plate to move at the surface.

There are other forces moving plates as well, but slab pull is the main one.

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Impress the teacher and the whole class by mentioning "slab pull!"

This is a relatively new idea, so only scientists who study the Earth know about it.

Don't be surprised if the uneducated masses still think that the answer is mantle convection.

(If anyone tells you that slab pull is not the answer, just direct them to the references that I have cited below.)

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Driving Mechanism For Plate Tectonics

That is a trick question because there are three driving mechanisms of plate tectonics. The three mechanisms are Ridge Push, Slab pull, and Convection. If you need the definition of these three mechanisms, comment i will tell you the answer. Ask me anything based on the three mechanisms. I will respond. Now I need to do my homework. Bye! :)

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RE:

What is the driving mechanism of plate tectonics?

Jim Z and Jenny S. already beat me to it. I don't need to restate it since it is already there twice. If you take a look at you tube or some other form of video it will show you this process in action. In science classes in particular geology or environmental science the teacher would show a video that illustrated the energy source of the plate motion and the driving mechanism of the convection current.

Convection in the mantle. It's not lava, since lava only exists on the surface. Pressure and temperature differences in the mantle cause convection, driving the tectonic plates to converge, diverge or slide by each other.