1. The Moving Crust
Topic 4

2. The Moving Crust
The crust is the top layer of the Earth. It also includes the minerals in the rocks below it.

3. The Crust

4. The Mantle The Earth’s mantle is made up of a plastic rock layer
Plastic means it is melted and gooey, but not completely liquid
The mantle can flow, but very slowly.

5. The Mantle

6. The Core The Core of Earth is very hot – around 6000oC
The outer core is liquid iron and nickel around 5500oC
The intense heat and pressure have made the inner core a solid ball

7. The Core

8. Continental Drift
The shape of land is constantly changing.

9. Continental Drift

10. Evidence - Wegener
Alfred Wegener was one of the first scientists to question plate movement
He formed the Theory of Continental Drift

11. Evidence

13. Evidence – Sea Floor Spreading

14. Evidence - Technology Sonar uses sound wave to make measurements
Sonar identified the Mid-Atlantic Ridge
Magnetometers detect the direction and strength of a magnetic field
The magnetic field of the crust in the Atlantic sometimes pointed south, instead of north
these are called reversal strips

15. Mid-Ocean Ridges

16. Evidence - Technology

17. The Theory of Plate Tectonics
Technology showed that the Earth’s crust is moving
The crust is made up of plates of rock that fit like puzzle pieces
Converging plate are coming together
Diverging plates are moving apart
Canadian Scientist J. Tuzo Wilson also concluded that plates can slide past each other

18. Plate Tectonics

19. Subduction Subduction zones are where plates are converging.
Subduction is when one plate slides underneath another.

20. Subduction

21. Plate Tectonics

22. Plate Movement

23. Plate Movement

24. Mariana Arc (& Trench)

25. Earthquakes
Topic 5

26. Earthquakes
Earthquakes are caused by sudden movements in the tectonic plates.
Seismic is of or having to do with the movement of tectonic plates
Seismologists can use seismographs to measure the intensity of an earthquake
It is attached to the bedrock to detect vibrations

27. Earthquakes
Liquefaction is the process of a solid taking on fluid qualities, like quicksand
Tsunamis are huge waves that happen when an earthquake occurs under the ocean
(Japanese word meaning 'harbour wave')
Avalanches or rock slides occur in mountains as a result of an earthquake

28. Richter Scale Earthquakes are gauged on the Richter scale up to 10.
Less than 2 is not generally felt, above 8 totally destroys communities and structures

29. Smallest earthquake detectable by people. 5.0
Table 1: Relationship between Richter Scale magnitude and energy released.
Richter Scale
Energy Release (J)
Comment
2.0
1.3 x 108
Smallest earthquake detectable by people.
5.0
2.8 x 1012
Energy released by the Hiroshima atomic bomb.
7.6 x 1013 to 1.5 x 1015
About 120 shallow earthquakes of this magnitude occur each year on the Earth.
6.7
7.7 x 1014
Northridge, California earthquake January 17, 1994.
7.0
2.1 x 1015
Major earthquake threshold. Haiti earthquake of January 12, 2010 resulted in an estmated 222,570 deaths
7.4
7.9 x 1015
Turkey earthquake August 17, More than 12,000 people killed.
7.6
1.5 x 1016
Deadliest earthquake in the last 100 years. Tangshan, China, July 28, Approximately 255,000 people perished.
8.3
1.6 x 1017
San Francisco earthquake of April 18, 1906.
9.0
Japan Earthquake March 11, 2011
9.1
4.3 x 1018
December 26, 2004 Sumatra earthquake which triggered a tsunami and resulted in 227,898 deaths spread across fourteen countries
9.5
8.3 x 1018
Most powerful earthquake recorded in the last 100 years. Southern Chile on May 22, Claimed 3,000 lives.

31. Seismic Waves
Seismic waves are the energy waves that travel outward from the source of the earthquake.

32. Primary Waves Primary or p waves are fastest
Can go through solids, liquids and gases.
Compression vibrations before an actual earth quake.

33. Secondary Waves Secondary or s waves slower
Only pass through solids not liquids or gasses.

34. Surface Waves Surface waves are the slowest
Move like ripples - rolling motion
Most destructive
Created when p and s waves collide

35. Earthquake Location
The time between P and S wave can help locate the source of an earthquake
The source of an earthquake deep in the crust is called the focus
The location directly above the focus is called the epicenter of an earthquake
Aftershocks are actually smaller earthquakes from the same focus

36. Earthquakes

37. Earthquake Location
Primary waves are bent or refracted as they travel through the Earth
The area where they do not come through the other side of the earth is called a shadow zone

40. Think about it!
How could the earthquake in Kobe, Japan have been recorded on Richter scales in Manitoba?

41. Distribution of earthquakes with a magnitude less than 5
Distribution of earthquakes with a magnitude less than 5.0 relative to the various tectonic plates found on the Earth's surface.

42. Distribution of earthquakes with a magnitude greater than 7 on the Richter Scale.

43. Faults
Rock located where tectonic plates meet is under very high pressure
If the rock is bent or stretched enough the rock can break creating a fault through the crust
There are three types of fault movement between the tectonic plates
Fault movement creates earthquakes
The Big One

44. Faults Normal Faults Reverse Faults Slip, Strike or Transform Faults
Tension or pulling action, which breaks rocks apart
North Atlantic
Reverse Faults
Compressive , causing rock to bend break and buckle
Marianas Trench, near Japan
Slip, Strike or Transform Faults
Shear forces causes slipping which and jagged edges break off
Pacific Plate

45. Normal Faults

46. Reverse Faults

47. Slip Faults

48. San Andreas