- An earthquake is the shaking of the Earth's surface caused by a sudden release of energy in the Earth's crust. This release of energy creates seismic waves that make the ground shake. Earthquakes can vary in size and intensity, from small tremors that are barely felt to large ones that can cause significant damage. The point on the Earth's surface directly above where the earthquake originates is called the epicenter. Earthquakes can occur due to natural processes or human activities, like mining/drilling.