1. EARTHQUAKES (DAY 2) Earth’s Structure

2. Do Now: 1. What type of wave will arrive first? 2. What type of wave can only travel through solids? 3. What is the difference between the epicenter and the focus?

3. Aim, Learning Target and Agenda AIM: How does knowledge of P and S wave behavior help us understand the structure of the earth? How is the severity of earthquakes measured? Learning Target: I can describe the various components of earthquakes and how this relates to the structure of the earth. Agenda: Do Now Going over HW Earthquakes & Earth’s Layers Mercali & Richter

4. Which type of earthquake wave is most destructive and why Lets Guess! Now, lets take a look at the animation: http://www.classzone.com/books/earth_science/terc/content/vis ualizations/es1002/es1002page01.cfm

5. If the waves could go through everything…

6. Behavior of the P Waves P waves could reach the other side of the earth The speed of P- waves decreased at a depth of 2900 km.

7. Behavior of the P Waves The speed of P- waves decreased at a depth of 2900 km. What is at a depth of 2900 km?

8. Behavior of S waves No S waves could reach the other side of the earth

9. P waves can travel through the entire earth S waves can only travel through the mantle. P waves can travel more.

10. Lets Look at it animated: http://www.classzone.com/books/earth_science/terc/content /visualizations/es1009/es1009page01.cfm

11. Structure If P waves can travel through solids, liquids, and gas, then they can go through all layers of the earth. If S waves can travel through solids only, then they can only go through the mantle and NOT the liquid outer core.

12. Discovering Earth’s Layers During the twentieth century, studies of the paths of P and S waves through Earth helped scientists identify the boundaries of Earth’s layers and determine that the outer core is liquid.

13. Discovering Earth’s Waves Seismic waves from even small earthquakes can travel around the world. This is why a seismograph in Antarctica can record earthquakes in California or Italy.

14. How do we measure the intensity of earthquakes? Richter Scale Moment Magnitude Mercali Scale

15. Richter Scale Outdated method Based on the height of the largest seismic wave Each level is a difference of 10x Ex: an EQ of 5.0 is 10 times greater than an EQ of 4.0

16. Moment Magnitude Estimates the energy released by earthquakes Calculated using many factors, along with seismic data. Factors include: Avg movement along fault Strength of the broken rock

17. Mercalli Scale Rates earthquake’s intensity at different locations Ex: an earthquake may be rated VIII (severe damage) near the epicenter, but only IV (light damage) 50 km away. Scale has twelve steps in Roman Numerals

18. Practice Q’s Most inferences about the characteristics of Earth’s mantle and core are based on 1. the behavior of seismic waves in Earth’s interior 2. well drillings from Earth’s mantle and core 3. chemical changes in exposed and weathered metamorphic rocks 4. comparisons between Moon rocks and Earth rocks