1. Do Now Question Why do you think the areas in pink and red have the highest earthquake risk?

2.  In “earthquake zones” – places where a large number of faults are located  MOST earthquake zones are at tectonic plate boundaries  SOME earthquake zones can be in the middle of a tectonic plate  Earthquakes occur at or near the surface of the Earth

3.  Increased stress caused by tectonic plates pushing, pulling, or slipping past one another  Watch this! Watch this! San Francisco

4. 1. Elastic Deformation ◦ temporary change in the shape of a rock due to built-up stress 2. Elastic Rebound ◦ the sudden release of elastically deformed rock to its original shape ◦ happens when stress is applied to a rock that it can’t withstand ◦ energy is released in seismic waves creating an earthquake

5.  Fastest  Body wave – travels through the interior of the Earth  Travels through solids and liquids  Squeezes and stretches rock as it moves through it  Nicknamed the “push-pull” wave  Least powerful wave

6.  2 nd fastest  Body wave – travels through the interior of the Earth  Travels through solids only!  Pushes rock side- to-side as it snakes through it  2 nd most powerful wave

7.  Slowest  Surface wave – only travels along the ground surface of the Earth  Causes rock to move in a circular motion like ocean waves (up, down, and around)  Most powerful wave –it causes the most damage.

8.  Seismic waves travel faster through objects that more dense ◦ Molecules are closer together and more tightly bonded  Seismic waves travel slower through objects that are less dense ◦ Molecules are further apart so they have a weaker bond

9.  Click here! Click here!

10.  United States daily earthquakes United States daily earthquakes  Live worldwide earthquake data Live worldwide earthquake data