Describe the world-wide distribution pattern of earthquake activity. Explain the earthquake magnitude scale and the Modified Mercalli scale of earthquake intensity. Explain how the epicenter of an earthquake can be located. Describe the effects of earthquake activity. Vibration of the Earth produced by the rapid release of energy.
Energy radiates out from the focus .
The focus is the place within the Earth where the rock breaks, producing an earthquake. Energy moving outward from the focus of an earthquake travels in the form of seismic waves . The epicenter of an earthquake is the point on the ground's surface directly above the focus. Brittle materials break during elastic deformation. Movement along a fault produces earthquakes and seismic waves.