8.1 Earthquakes
Chapter 8: Earthquakes
Earthquake -- the vibration of Earth
produced by the rapid release of energy
• Focus -- the point within Earth where the
earthquake starts
• Epicenter -- the location on the surface
directly above the focus
• Fault -- fracture in Earth where movement has
occurred
Focus, Epicenter, and Fault
Slippage Along a Fault
Causes of Earthquakes
 Elastic Rebound Hypothesis
1. Rocks bend and stored energy builds up.
2. Rocks break and slip. Rapidly releasing
energy. (Earthquake)
3. Rocks bounce back into original shape.
Elastic Rebound Hypothesis
Aftershocks and Foreshocks
• aftershock -- small earthquake that follows the
main earthquake.
• foreshock -- small earthquake that often
comes before a major earthquake
Seismic Waves radiate from focus and
transmit energy.