MEMPHIS, Tenn. (WMC) - An earthquake occurs when there is movement in the land below Earth’s surface.
The Earth is made up of several layers--a solid inner core, liquid outer core, hot solid mantle and a solid outer crust. The crust and mantle are the skin of the Earth and are fitted together like a puzzle. These pieces, which we call tectonic plates, are slowly moving and shifting.
The edges of these plates are called plate boundaries and these are where faults are located. Earthquakes are most common along these fault lines as the Earth’s plates are colliding together. One of the most well known in the U.S. is the San Andreas Fault in California.
So why does the Earth violently shake when there’s an earthquake? The edges of these plates are jagged and rough, so they will get stuck on each other when they try to move. When the plates are stuck together and friction is high, the energy is stored. When the plates disconnect and release, the stored energy is released. That energy is released outward from the fault line in seismic waves. These waves of energy move through the Earth’s surface and cause it to shake.