1. EARTHQUAKES Year 1 Science

2. EQ: WHAT 3 STRESSES LEAD TO EARTHQUAKES?

3. EARTHQUAKES

4. EARTHQUAKES ARE… Natural vibrations of crust that are caused by stress from plate tectonics

5. 3 TYPES OF STRESSES Compression:  The squeezing of rock together until it folds or breaks

6. 3 TYPES OF STRESSES Tension:  The pulling of the crust until materials thin and break

7. 3 TYPES OF STRESSES Shear  Pushing rocks into 2 opposite directions

8. EARTHQUAKE WAVES Vibrations of the ground during an earthquake are called seismic waves.  3 Types of Seismic Waves:  Primary Waves: waves that cause rock particles to move back and forth  Secondary Waves: cause rocks to move at right angles in relation to the wave  Surface Waves: waves that cause particles to move in two directions: up and down, side to side

9. Epicenter The point on Earth’s surface directly above the focus Focus The point below ground where the earthquake originates

10. MEASURING EARTHQUAKES

11. SEISMOMETERS Scientists use seismometers to measure ground movement caused by seismic waves

12. The strength of an earthquake = magnitude (a # given to an earthquake based on its strength)

13. RICHTER SCALE MEASUREMENTS ScaleDamage 0-4Minor 4-5Light 5-6Moderate 6-7Strong 7-8Major 8+Catastrophic

15. NOTE REVIEW -Highlight the following headings: -3 Types of Stresses -3 Types of Seismic Waves -Measuring Earthquakes -Circle the following terms in BLUE: -Earthquake, Tension, Compression, Shearing, P- Waves, S-Waves, Surface Waves, Epicenter, Focus, Seismometer, Magnitude -Underline the definitions for the circled terms from above in GREEN