Chapter 7.1  (Earthquakes)
 
 

Chapter 7 Earthquakes - movements of the earth's crust when plates shift and release stored energy As rocks move, potential energy becomes kinetic energy (seismic waves) - vibrations are produced by earthquakes. Most earthquakes occur along faults. Stress builds along each side of a fault until it reaches its elastic limit.  Then the rocks break, releasing their energy.  (EARTHQUAKE!!!!!!!!!) See an animation of a fault reaching its elastic limit. (Click here) Focus of an earthquake - where an earthquake actually begins.  This may be below the earth's surface. Epicenter of an earthquake - the point on the earth's surface directly above the focus. Types of seismic waves:     Primary (P) waves are longitudinal, arrive first     Secondary (S) waves transverse, arrive next     L waves (surface) when P and S waves get to the surface - they cause the most damage Seismographs detect seismic waves Richter and Mercalli Scales describe the strength of an earthquake. The Richter magnitude is based on the amount of shaking caused by an earthquake. Each increase of 1 on the Richter scale equals an increase of 10 in the amount of shaking. The Mercalli scale is based on the amount of damage done. Earthquake zones- - near the edges of plate boundaries "Ring of Fire" extends nearly all the way around the Pacific Ocean Mid Atlantic Ridge  - new ocean crust is being formed as the ocean floor spreads  Mediterranean - Asian belt - plates are colliding, causing earthquakes.