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.