1. Earthquakes

2. Why Earthquakes happen
Fault: a fracture in a rock formation where movement occurs

3. What is an earthquake?
Earthquake: the sudden release of energy in earth’s crust

4. Elastic Rebound
Elastic rebound: rock moved by an earthquake quickly returns to its original position

5. Fence offset 8 1/2 feet by main fault in rural California1906.

7. Anatomy of an Earthquake
Focus: the location inside of the Earth where the motion occurs

8. Anatomy of an Earthquake
Epicenter: the location on Earth’s surface directly above the focus

9. Seismic Waves
Seismic Waves: Vibrations caused by earthquakes

10. Seismic Waves
Body waves: seismic waves that travel through earth’s interior
Two types:
Primary waves: (P-waves) Fastest and the first to be detected
Can move through solids, liquids, or gas

11. Body Waves continued
Secondary waves: (S-waves) shake the ground moving it up and down
Can move through solids ONLY

12. Animation

13. Surface waves
Surface waves: earthquake waves that move along the surface of Earth
Slower, but cause the most damage

14. Surface Waves
Love waves: fastest surface waves
Move rock side to side

15. Diagram of love wave

16. Surface Waves Rayleigh waves: also called a “ground roll”
Moves rock in a circular motion

17. Seismic Waves and Earth’s Interior
Seismic waves change speed and direction as they enter a new material
Andrija Mohorovicic (1909): used seismic waves to find the depth of the mantle

18. Seismic Waves and Earth’s Interior
Shadow Zones: locations on Earth’s surface where earthquake waves are not detected because the waves cannot travel through liquid
animation

19. Studying Earthquakes
Seismograph: an instrument that detects and records seismic waves
seismograph

20. Measuring Earthquakes
Magnitude: the strength of an earthquake

21. Measuring Earthquakes
Richter Scale: assigns a number to define the energy released during an earthquake
richter scale explained

23. Measuring Earthquakes
Big numbers = larger amounts of energy released
Intensity: the amount of damage caused by an earthquake
Taiwan (1999)

24. Tsunamis
Tsunami: a giant wave caused by an earthquake on the ocean floor
tsunami

26. Earthquake Safety

27. Earthquake Safety
Earthquakes are more likely to happen in some places, but can happen anywhere
Before: have emergency supplies on hand
Such as: food, water, flash lights, batteries, radios and a first aid kit
During: stand in a doorway or get under a table
Protect your head from falling objects
Drop, Cover and Hold On
After: be cautious of fires, downed powerlines, broken pipes etc.
Remove yourselves from buildings and check for structural damage.

29. Earthquake Warnings/Forecasts
Studying past earthquakes can help us predict future quakes
Foreshocks usually happen before a larger earthquake
There is NO reliable way to predict earthquakes
can we predict earthquakes?

30. Tsunamis

31. amazing earth (patrick stewart)