2. Earthquakes Natural vibrations of Earth’s ground caused by: - Movement along tectonic plates -OR -Volcanic eruptions

3. Forces Within Earth Fracture caused when: -the forces acting on the Earth’s Crust exceed the strength of the Crust and Rocks The Deformation of material caused by: -Stress In the Forms of: - Compression - Tension - Shear

4. Earthquakes occur at the boundaries of tectonic plates. See a lot of EQ’s in places like Japan and California. FACT: 3 million earthquakes happen every year!

6. Faults A fault is the fracture or system of fractures along which movement occurs. The surface along which the movement takes places is called the fault plane.

7. Types of Faults

8. Reverse faults are fractures that form as a result of horizontal compression. Normal faults are fractures caused by horizontal tension. Strike-slip faults are fractures caused by horizontal shear.

10. When rocks break during an earthquake energy is released in the form of seismic waves. These waves travel in all directions. Focus is the exact point within the earth where the rock first breaks. Epicenter is the point on the surface immediately above the focus.

15. Waves spread out as a wave travels.

16. 3 types of waves associated with an EQ p-wave s-wave surface wave

17. P-WAVE primary wave longitudinal type wave fastest wave: 6 km/sec

18. Longitudinal

19. S-WAVE secondary wave transverse wave ½ speed of a p-wave: 3 km/sec they do not travel through liquids

20. Transverse

21. Transverse Waves A wave that causes the particles of the medium to vibrate perpendicularly to the direction the wave travels.

22. SURFACE WAVE they travel along earths surface it’s the wave you “feel” during an earthquake up/down and back/forth motion slowest of all 3 waves

23. Surface Waves Occurs in a liquid Circular particle motion

24. Surface Waves Occur at the boundary of two different mediums such as water and air.

25. Surface Waves cont Surface waves have a rolling pattern of particle motion.

27. Raleigh Waves Occurs in solid rock Particles move in elliptical path