1. Plate Movement Effects
What are the effects of tectonic plate movement?

2. Recall that a conservative plate boundary does not destroy or create lithosphere; plates slide past each other. These are also called transform plate boundaries.

3. The surface where 2 plates slips past each other is known as a fault plane.

4. The area on the surface of the earth above the hypocenter is the epicenter (epi means upon).

5. The focus or hypocenter is the region within the earth where the earthquake begins (hypo means below).

6. Tectonic plates are not even at the edges.

7. Plates slide past each other with sinistral or dextral motion and the uneven edges stick together. The rest of the plate continues to move.

8. Eventually, as the plate continues to move, the stuck edge becomes unstuck releasing energy in all directions resulting in seismic waves.

9. P and S waves are known as body waves since they can travel through the earth’s interior. Surface waves travel in ripples along the earth’s surface and include Love waves and Rayleigh waves.

10. A seismometer is used to measure the magnitude of an earthquake
A seismometer is used to measure the magnitude of an earthquake. Works by tracing a seismogram to record earth’s motion.

11. P waves always arrive before S-waves
P waves always arrive before S-waves. The time difference between P and S waves is called the lagtime. The smaller the lagtime, the closer the seismometer is to the epicenter. Why? ? ? ?

12. Body waves have same source but different speeds
Body waves have same source but different speeds. Time separation between them dependent on distance from epicenter.

13. Surface waves have lower frequencies than body waves.

14. Surface waves have lower frequencies than body waves.

15. Surface waves arrive AFTER Body waves.

16. Surface waves cause most of the damage.

17. Love waves: faster than Rayleigh waves and move side-to-side.

18. Rayleigh waves roll along the ground moving up and down AND side-to-side. Similar to the way a water wave moves.

19. Rayleigh waves are responsible for most of the shaking.

20. Richter Scale (RS) used to measure EQ magnitude based on largest seismic wave amplitude.

21. Units of RS represent a 10 fold increase in magnitude and release of energy that is 31 fold. An EQ with RS = 6 releases 32 times more energy than an EQ with RS = 5.

22. An 8. 2 EQ is how much greater in magnitude than a 6. 5 EQ. Answer: 8
An 8.2 EQ is how much greater in magnitude than a 6.5 EQ? Answer: 8.2 – 6.5 = = 50 times greater.

23. RS limitations: Accuracy above 8.0 diminishes.

24. RS limitations: Is based only on largest seismic waves
RS limitations: Is based only on largest seismic waves. Ignores smaller waves. RS value not good damage indicator.

25. Moment Magnitude Scale (MMS) uses the area of fault rupture AND seismograph data.

26. MMS is more accurate than RS and can measure EQs above 8
MMS is more accurate than RS and can measure EQs above 8.0 on the RS and below 0 on the RS.

27. Moment magnitude is based on seismic moment M0, which is M0 = μ x A x D. μ = rigidity constant. A = area of fault slip. D = distance of slippage.

28. Rigidity Constant is based on the rigidity of the sliding rocks
Rigidity Constant is based on the rigidity of the sliding rocks. Higher rigidity means more energy released during slippage and larger μ value.

29. The area of slippage is the area that is “uncovered” at the fault slip.

30. Distance of slippage is the length that the rock slipped at the fault zone.

31. Moment Magnitude (MM) = (2/3) Log M0 – 5
Moment Magnitude (MM) = (2/3) Log M0 – 5.7 The constants are chosen so that the MM matches the other EQ scales for smaller EQs.

32. For MMS, the energy released from a 5
For MMS, the energy released from a 5.0 EQ is 1024 greater than the energy released from a 3.0 EQ. 5.0 – 3.0 = 2.0, 322 = 1024 Joules.