What is an earthquake – really? We think of the ground beneath our feet as being “rock solid” and never changing. In reality, the earth is subjected to tremendous forces that bend, push, and break brittle rock. When rocks break or slip past each other along a fault, the built-up energy is released into the earth as vibrations. The vibrations are sound waves or seismic waves that move away from the source in all directions. Seismometers are instruments used to detect seismic waves. The instrument