WHAT IS EARTHQUAKE? An earthquake (also known as a quake , tremor or temblor ) is the shaking of the surface of the Earth, resulting from the sudden release of energy in the Earth 's lithosphere that creates seismic waves . Earthquakes can range in size from those that are so weak that they cannot be felt to those violent enough to toss people around and destroy whole cities. The seismicity , or seismic activity, of an area is the frequency, type and size of earthquakes experienced over a period of time. The word ...