(Phys.org) —We all know that the Earth rotates beneath our feet, but new research from ANU has revealed that the center of the Earth is out of sync with the rest of the planet, frequently speeding up and slowing down.
"It's stunning to see that even 10, 20 or 30 years apart, these earthquakes look so similar. But each pair differs very slightly, and that difference corresponds to the inner core. We have been able to use that small difference to reconstruct a history of how the inner core has rotated over the last 50 years," he said.
The crust and upper mantle form the lithosphere,
which is broken up into several plates that float on top of the hot molten mantle below.
The crust thickness averages about 18 miles (30 kilometers) under the continents,
but is only about 3 miles (5 kilometers) under the oceans. It is light and brittle and can break.
In fact it's fractured into more than a dozen major plates and several minor ones.
It is where most earthquakes originate.
The mantle is more flexible – it flows instead of fractures.
It extends down to about 1,800 miles (2,900 kilometers) below the surface.
The core consists of a solid inner core and a fluid outer core.
The fluid contains iron, which, as it moves, generates the Earth’s magnetic field.