The term for the location within the Earth where an earthquake begins is

• A. Focus
• B. Epicenter
• C. Fault
• D. Earthquake

Answer: (A)

The starting point of an earthquake is the focus, the location inside the Earth where rocks first rupture and energy is released as seismic waves. The focus can be shallow or deep along a fault, and from there waves radiate outward. The point on the Earth's surface directly above this spot is the epicenter, which is useful for describing where the shaking is felt, but it isn’t where the earthquake begins. The fault is simply the fractured rock along which movement occurs, and the earthquake refers to the entire event. So the term for the location within the Earth where an earthquake begins is the focus.