1. Exploring Earth’s structure using Occam’s Razor Prepared by Michael Hubenthal, IRIS Consortium Adapted from Braile, 2000 & DLESE Teaching Boxes, 2008

2. How do you know what is inside? What is inside ?

4. What is inside here? Think, Write, Pair, Share How do you know what is inside?

5. How do you know?

6. Occam’s Razor - All other things being equal, the simplest solution is the best Based on your “evidence” what is beneath our feet?

7. Calvin and Hobbes by Bill Watterson Why are model important in science?

8. Could this help us test our model?

9. Theoreticians Seismologist

13. Theoreticians Seismologist

14. Earth’s surface Center of the Earth Scale model of a homogeneous Earth

16. 140°

18. Seismologists Theoreticians

27. Creating a travel-time plot Work in teams of ~ 2 Each pair calculates 3 travel times Each team makes 1 travel time plot, 0-180 degrees Discuss results Use velocity=11 km/sec, distance scale 320 km/cm 10 30 40 50 70 80 100 115 130 150

28. What is the cause of model and observations mismatch?

29. Shadow zone Something changes beyond ~110 deg.

30. Combine results from multiple earthquakes Assumptions?

31. ?

32. What has your data established so far? Have we found any layers?

35. 1st: 1 deg -.5 min 2nd: 16 deg - 3.5 min First Arrivals

43. http://rev.seis.sc.edu/

44. http://rev.seis.sc.edu/ > DLESE Teaching Boxes!DLESE Teaching Boxes! Updated Version