1. EaRtHqUaKeS!

2. More than 700 Earthquakes that are strong enough to cause damage occur every year. Earthquakes are caused by stress applied to rocks from the movement of tectonic plates.

3. Stress builds up in the rock, until there is a sudden release - an earthquake. Much like a bending twig. The release of energy is a seismic wave.

4. The actual site where the rock slipped is called the focus. Right above the focus on the surface is called the epicenter.

5. Most earthquakes occur along plate boundaries. (90%) Sometimes there are intraplate earthquakes that are far from boundaries. These are not well understood.

6. Divergent boundaries- shallow temblors (tremor as a result of plate shifting) Transform boundaries- mild or moderate Convergent boundaries- strongest earthquakes.

7. Ring of Fire

8. 80% of the world biggest Earthquakes occur in the Ring of Fire. It is also where 75% of the worlds volcanoes are located. A place of many convergent boundaries.

9. Measuring Earthquakes Most earthquakes are measured by using a seismometer. A pen that draws a line on to paper. When the earth shakes the pen shakes.

10. Richter Scale VS. MMS The magnitude of an Earthquake can be measured using the Richter Scale or the Moment Magnitude Scale. Richter Scale Invented in 1935 by Charles F, Richter. It is a logarithmic scale. Each point is 10x more energy than the previous.

11. Moment Magnitude Scale MMS is used by modern geologists. -Fixes problems with seismometer calibration -No upper limit (7.0 highest on the Richter scale) -Measures direct energy vs. specific seismometer movement readings. -5.0 on Richter = 5.0 on MMS, similar values for 3.0 – 7.0 earthquakes.

12. A magnitude 7.0 shakes 10 times more than a 6.0 earthquake and 100 times more than a 5.0 earthquake.

13. Seismic Waves Body Waves -P-Waves -S-Waves Surface Waves -Love -Rayleigh

14. P-Waves Primary Waves – longitudinal, (sound waves above surface), fastest type of seismic wave. Used with S-Waves to calculate density and material of inner earth. Velocity = 330 m/s in air, 1450 m/s in water and about 5000 m/s in granite. granite

15. S-Waves Secondary Waves – A slower, transverse wave following P-Wave. Both P-Waves and S-Waves can travel through rock. S-Waves are generally 40% slower than P-Waves in any given material.

16. S-Wave

17. Surface Waves Love Wave – Transverse waves, parallel to the surface. Causes side to side and up and down ripples on the Earth’s surface. Amplitude decreases with depth. Material returns to its original shape after wave passes

18. Love Wave

19. Rayleigh Waves Motion consists of elliptical/circular motions in the vertical plane and parallel to the direction of propagation. Amplitude decreases with depth.