Asthenosphere and Lithosphere
The tectonic plates are made up of Earth’s crust and the upper part of the mantle layer underneath. Together the crust and upper mantle are called the lithosphere and they extend about 80 km deep. The lithosphere is broken into giant plates that fit around the globe like puzzle pieces. These puzzle pieces move a little bit each year as they slide on top of a somewhat fluid part of the mantle called the asthenosphere. All this moving rock can cause earthquakes.
Watch this video to see awesome facts about the athenosphere and lithosphere!