1. Changing Earth
Movement in Earth

2. Questions to Answer
How does the movement of tectonic plates affect the Earth’s surface?
How does the transfer of energy relate to earthquakes and volcanoes?
How do humans prepare and respond to natural events?

3. Earth’s Interior

4. I. Earth’s Interior A. Three major layers of the Earth
1.Crust – outermost & thinnest layer
Cool and solid rock
Divided into continental and oceanic crust
2.Mantle – middle layer
Hot and liquid rock, 80% of Earth’s volume
3.Core – center layer of earth
Divided into inner and outer core
Outer = hot and liquid metal (iron & nickel)
Inner = hot and solid metal “ “

5. Earth’s Interior 1.Continental Crust 2.Oceanic Crust Less dense
Thicker, deepest beneath mountains
2.Oceanic Crust
Beneath the ocean water
More dense
Thinner

6. B. Plate Tectonics
1. Alfred Wegner introduced the idea of Pangaea (noticed coastlines fit together)
A large supercontinent
2. Broke apart because of plate tectonics –theory that Earth’s surface is made of large moving plates
Moving of Earth’s plates
Causes the land to look different on Earth

8. Plate Tectonics 3. Movement happens because Earth’s makeup
a. Lithosphere
Crust and rigid upper mantle
These are the ‘plates’, 7 large pieces & several small pieces (tectonic plates)
b. Asthenosphere
Mantle just below the lithosphere
Very liquid and slowly flowing

9. Plate Tectonics

10. C. Plate Boundaries
1.Any place plates meet and move is known as a fault (crack in Earth)
Three Types of Plate Boundaries
a. Divergent Boundary
Move apart
b. Convergent Boundary
Move together
c. Transform Fault Boundary
Move along side (scrape past each other)

11. 2. Divergent Boundary Cause trenches and ridges (mid-oceanic)
Forms new crust, magma rises between-
Rift valley- most studied- Mid-Atlantic Ridge

12. 3. Convergent Boundary Cause trenches, volcanoes, mountains
Subduction occurs
More dense
oceanic crust
slides under
less dense
continental
crust

13. 4. Transform Fault Boundary
Cause rocks to crack and break
Causes lots of earthquakes

14. D. Evidence
1. Magnetic rocks
in the earth
change polarity

15. Evidence
2. Land shapes
3. Fossils
4. Ancient climates

16. Tectonic Plates

17. II. Earthquakes and Volcanoes

18. A. Earthquakes
1. Shaking or trembling caused by the sudden release of energy
2. Usually associated with faulting or breaking and slipping of rocks
a. Occur at boundaries of plates
b. Release energy that create seismic waves
3. Continuing adjustment of position results in aftershocks

19. Movement of Rock

20. Earthquakes 4. Focus 5. Epicenter
The point underground where the rocks start to slip
Where the earthquake begins
5. Epicenter
Spot on the surface directly above the focus (greatest damage here)

21. Earthquakes

22. Earthquakes 6. Types of seismic waves a. P waves (primary waves)
Fast moving longitudinal waves
First waves we detect
b. S waves (secondary waves)
Slow moving transverse waves
Second waves we detect
c. Surface waves
Rolling wave ( & ) on the surface of Earth
Cause the most destruction, collapse of buildings

23. Earthquakes
P Wave
S Wave
Surface Wave

25. Earthquakes
7. Seismology
Study of earthquakes
Use a seismograph

26. Earthquakes a. Seismology
Three seismographs can tell you the location of the epicenter

27. Earthquakes
8. Measured using the Richter scale

28. Earthquakes

29. B. Volcanoes 1. A vent or hole in the crust 2. How a volcano erupts
a. Magma collects in a chamber under the surface
b. Pressure builds up as the chamber fills
c. Pressure gets so great magma rises to the hole and comes out as lava

30. Volcanoes

31. Volcanoes 3. Three types- determined by type of eruption a. Shield
b. Composite
c. Cinder cone

32. 1. Shield Volcanoes Eruptions are mild and occur frequently
Creates buildup of a gently sloping mountain
Magma is very runny and long flowing
Largest of all volcano types

33. 2. Composite Cone Volcanoes
Eruptions alternate between mild and explosive
Creates layers of lava, ash, & cinders, with steeper sides
Magma is thicker, cause most violent eruptions
Tallest of all volcano types

34. 3. Cinder Cone Volcanoes Eruptions are rare, but violent
Most of lava and ash builds up around vent –”cone”
Magma has lots of gas, causing explosion
Smallest and most abundant of all volcano types

35. C. Where are volcanoes? 1.Occur at convergent plate boundaries
Oceanic-Continental plates around the Pacific Ocean
“Ring of Fire” = location of 75% of volcanoes

36. Where are volcanoes? 2. Occur at divergent plate boundaries
Oceanic-Oceanic split, allowing mid-oceanic ridge to form

37. Where are volcanoes? 3. Occur at hot spots
In the middle of oceanic plates, magma comes up from hole
Form a “trail” of volcanoes as plate moves
seamount – volcanoes forming under water
Mantle plumes

38. Mt. St. Helens 1980