How the Tectonic Plates Move

Alfred Wegener was the first Scientist to propose that the continents fit together like a puzzle and over time moved apart. His idea was brilliant but he had a problem. He couldn’t explain how the plates moved apart.

Since this time Scientists have proposed at least four mechanisms to explain how tectonic plates move over the Earth’s surface. 

These four mechanisms include, 

Mantle convection

Ridge Push

Slab Pull

Slab Suction

The core of the Earth is extremely hot and is so hot it turns rock into a liquid called magma. The hottest magma rises upward as this magma reaches the surface it cools and sinks back down. This creates a convection current. The convection currents are similar to the movement of these beans. Notice how the beans rise, cool, then sink back down.

Ridge push newly formed rock at the mid-ocean ridge is warmer and less dense than the older rock. The less-dense rock rests on top of the older more dense rock. As a result, the older rock will slope downward and away from the ridge. This downward force called ridge push pushes the plate away from the mid-ocean ridge.

At subduction zones, the denser tectonic plate will sink or subduct beneath the less dense tectonic plate. The leading of the subducting plate sinks into the mantle pulls the rest of the plate with it. This process is called slab pull. This process relies on gravity to pull down the tectonic plate.

Slab suction occurs when small-scale convection in the mantle wedge pushes the plate further away from the ridge and back into the mantle. 

These actions cause the plates to move roughly 10 centimeters per year.

When tectonic plates move towards one another this is called a convergent plate boundary

When they move away from one another this is called a divergent plate boundary and when they move in opposite directions it is called a transform plate boundary.

6 Plate Boundaries

Rotation and Revolution

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