Earth's mantle is way fewer stable Video that we thought it was - Physics-Astronomy.org

Earth's mantle is way fewer stable Video that we thought it was

The ground isn’t as hard as we'd like to believe. It’s split into interlocking puzzle pieces called tectonic plates that ride on top of an underlying layer of rock known as the mantle. Where those plates collide, it produces fault lines and volcanoes, so understanding the movement of the mantle could someday lead to advances in our ability to predict earthquakes and eruptions.
It’s solid seeing beneath those plates, though, so there’s a lot we still don’t know about the mantle of our home planet. But researchers in the UK have just made a big step forward in understanding and modeling how the mantle moves. It turns out that it’s much more forceful than we thought.
The mantle is a huge layer of solid rock about 3,000 kilometers thick, that over the course of millions of years, moves a bit like a really thick liquid. The crust (where we live) floats on top of the mantle - so it moves when the mantle moves.
In the past, scientists mostly focused on the mantle’s side-to-side movement, which is what moves tectonic plates around and rams them mutually to cause earthquakes, mountain ranges, trenches, and volcanoes.
The sideways motion is physically powerful enough to move whole continents around, but it can also vary over just a couple thousand kilometers - meaning that if you go a few thousand kilometers from where you’re sitting, you might end up where the mantle is dragging the crust in a different direction.
 They also found that it has much bigger effects than those models had predicted. The mantle can push or pull a piece of the crust a kilometre or more out of line with the crust around it.
So if you’re in Hawaii, where the mantle is pushing up, you’re about a kilometer farther from the core than you otherwise would be. And if you’re in eastern South America, you’re about a kilometer closer to Earth’s core than you would be without the mantle pulling on the crust beneath your feet.
Earth's mantle is way fewer stable Video that we thought it was
The team discovered this primarily by comparing the crust’s thickness to its age. With those data in hand, they could figure out how much of the crust’s topography - the way its height varies across Earth’s surface - was due to things like plate tectonics, and how much of it was due to the crust actually being pushed up or pulled down by the underlying mantle.
But they didn’t stop there. They were also able to describe their findings mathematically with a new model of the way temperature variations in the mantle change its movement. This model and these measurements give Scientists a much better idea of what’s going on in the mantle than they’ve ever had before.

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