1. Earthquakes

2. What is an earthquake? Earthquake: a sudden release of energy in earth’s crust that causes movement

3. Why Earthquakes happen Friction prevents movement along a fault Fault: a fracture in a rock formation where movements occurs Sudden release causes a quake

4. Elastic Rebound Elastic rebound: the sudden return of deformed rock to its original position

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

6. Anatomy of an Earthquake Focus: the location within Earth along a fault at which the first motion of an Earthquake occurs The shallower the focus, the more destructive the quake

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

8. Seismic Waves Seismic Waves: Vibrations caused by earthquakes

9. Body 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

10. Body Waves continued Secondary waves: S-waves- shake the ground back and forth (2 nd fastest) Can move through solids ONLY

11. Animation

12. Surface waves Surface waves: Only move along the surface of Earth Slower, but cause the most damage http://www.tjhsst.edu/~jlafever/wanimate/Wave_Properties2.html

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

14. Diagram of love wave

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

16. Seismic Waves and Earth’s Interior The composition of the material a seismic wave moves through affect their speed and direction Andrija Mohorovicic (1909): used seismic waves to find the depth of the mantle

17. Seismic Waves and Earth’s Interior Shadow Zones: locations on Earth’s surface where no body waves from a particular earthquake can be detected animation

18. Seismic Waves and Earth’s Interior P-waves are bent as they pass through different layers S-waves are blocked by the liquid outer core because they can only travel through solids

19. Activity 1: Seismic Waves Reflection and extension quiz

20. Studying Earthquakes Seismograph: an instrument that detects and records seismic waves Seismogram: the recorded tracing produced by a seismograph

21. Studying Earthquakes (cont.) Different waves move at different speeds: P-waves arrive first, then S-waves, then Surface waves

22. Locating an Earthquake The longer the lag time between P-waves and S-waves, the further away the earthquake is The location of an earthquake can be found by triangulation: using the distance from 3 stations to find the epicenter of the earthquake http://www.classzone.com/books/ earth_science/terc/content/investi gations/es1003/es1003page02.cfm ?chapter_no=investigation

23. Measuring Earthquakes Magnitude: the strength of a quake

24. Measuring Earthquakes Richter Scale: assigns a number to define the energy released during an earthquake https://www.yo utube.com/watc h?v=wVqYg4NP vC4https://www.yo utube.com/watc h?v=wVqYg4NP vC4 richter scale explained

25. https://www.y outube.com/w atch?v=1qbg7 orb1lc Bill nye

27. Measuring Earthquakes Big numbers = stronger earthquakes Taiwan (1999)

28. Measuring Earthquakes Intensity: the amount of damage caused by an earthquake

29. Tsunamis http://video.nationalgeographic.com/video/101- videos/tsunami-101 http://video.nationalgeographic.com/video/101- videos/tsunami-101

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

32. Earthquake Safety

33. Earthquakes are more likely to happen in some places, but can happen anywhere Before: have supplies on hand Such as: food, water, flash lights, batteries, radios and a first aid kit During: stand in a doorway, stay away from windows and tall things Protect your head from falling objects Drop, Cover and Hold On After: be cautious of fires, downed powerlines, etc. Remove yourselves from buildings and check for structural damage. http://www.classzone.com/books/earth_science/terc/content/visualizations/es1005/es1005pag e01.cfm?chapter_no=visualization

36. Earthquake Warnings/Forecasts Scientists study past quakes to predict where future quakes are most likely to occur There is No reliable way to predict when or where an earthquake will happen When stress is building up in rock, sensors can detect tilting and cracking Foreshocks usually happen before a large earthquake