Why Earth's Tectonic Plants Shift and Change Suddenly

Why do the tectonic plates beneath Earth's surface move so abruptly? Scientists may have found the answer. They've taken a closer look at these shifting plates and have discovered that the answer comes down to two main factors.

"Our planet is probably most distinctly marked by the fact that it has plate tectonics," said David Bercovici, lead author of the new study, in a news release. "Our work here looks at the evolution of plate tectonics. How and why do plates change directions over time?"

In the past, researchers believed that all tectonic plates were pulled by subducting slabs, which result from the colder, top boundary layer of the Earth's rocky surface becoming heavy and sinking slowly into the deeper mantle. This process, though, doesn't account for sudden plate shifts. This abrupt movement requires that slabs detach from their plates, but doing this quickly is difficult since the slabs should, in theory, be too cold and stiff to detach.

Now, the new research shows that there are other factors at play. There are two specific traits that make the difference: thick crustal plugs and weakened mineral grains. Thick crust from continents or oceanic plateau is swept into the subduction zone, plugging it up and prompting the slab to break off. When mineral grains in the slab start to shrink, the slab weakens rapidly and accelerates the detachment.

"Understanding this helps us understand how the tectonic plates change through the Earth's history," said Bercovici. "It adds to our knowledge of the evolution of our planet, including its climate and biosphere."

The findings are published in the journal Proceedings of the National Academy of Sciences.

For more great science stories and general news, please visit our sister site, Headlines and Global News (HNGN).