1. 8.E.5A.5/5B.1-3 Notes
2/26/2018

2. How do we know plate tectonics are real?
Distribution of fossils (aka Alfred Wegner)
Earthquakes
Continental and Ocean Floor Features
Mountains
Volcanoes
Faults
Trenches

3. 1. Alfred Wegner
REMEMBER: Continental Drift? Continents are moving but I have no idea why!
He had 4 clues (He had a few more but we don’t care) that he used to explain continental drift!
Puzzle Pieces
Fossils
Rock Strata
Coal

4. Puzzle Pieces
It fits like a puzzle! Different continents appear to be able to fit together like a puzzle. When they are all pushed together it forms PANGEA

5. Distribution of Fossils
Fossils of the same exact reptile were found on different continents. When the continents split different life forms developed on each continent. That is why we don’t notice similarities in today’s animals!

6. Rock Strata Correlation
The age and layering of the rock strata is identical in specific areas suggesting that at one time they were touching.
The distribution of rocks in Earth’s crust is a direct result of tectonic activity.

7. Coal Formations
Coal formations have been found in cold and dry climates when coal can only form in warm wet climates.
Like wise fossil remains of oceanic life have been found in the very top of mountain peaks.

8. So....What does that mean?
All of this only makes sense IF the continents move!
But HOW?

9. 2. Earthquakes!
Remember: Earthquakes most often occur at plate boundaries.
Interaction along plate boundaries results in an increased frequency of earthquakes at those locations.
Transform Boundary: San Andreas Fault, California

10. Earthquakes
Are they dangerous? Uhh yeah! BUT it also depends where you are at 
In order to understand how we are effected by earthquakes we first have to understand how they work.
EARTHQUAKES ARE NOT PREDICTABLE.
We study them to develop better technology to deal with their effects. WE CAN NOT PREDICT WHEN EARTHQUAKES WILL HAPPEN.

11. Seismic Wave
Energy spreads outward in all directions as vibrations

12. Earthquake Focus
The point where the energy is released

13. Primary Waves Move out from the earthquake focus
Primary waves are the fastest moving waves
These waves can move through solid and liquid layers of the Earth

14. Longitudinal Waves
Push and pull rock creating a back and forth motion in the direction the wave is moving.

15. Secondary Waves Moves out from the earthquake focus
Moves the slowest of all waves
These waves can move through solid rock

16. Transverse Wave
Moves at right angles to primary waves causing rocks to move up and down and side to side.

17. Surface Waves These form when P and S waves reach the surface
Can cause the ground to shake, making rock sway from side to side and roll like an ocean wave

18. Epicenter
The point on Earth’s surface directly above where the energy is released in an earthquake

19. Seismograph
A machine that measures seismic (earthquake) activity.

20. Seismogram
A written record of the vibrations caused by an earthquake.

21. Triangulation
Identifies the epicenter of an earthquake

22. 3. Continental Features Remember:
Mountains form at.....
Volcanoes form at.....
Rifts form at.....
Faults: A break in the Earth’s crust.
Volcanoes form at subduction zones where immense pressure pushes magma up through the crust.
The Ring of Fire has the most volcanic activity of anywhere else in the world.
Volcanic activity is constructive in that they add new rock to existing land.
Volcanic activity is destructive in that the eruption is explosive and damaging to all life.

23. 3. Oceanic Features Remember:
Seafloor Spreading form at.....
Underwater Volcanoes form at.....
Trenches: at a subduction zone a long narrow depression in the seafloor forms. These are the deepest parts of the oceans.
Volcanoes can occur at divergent boundaries.
Upwelling (pushing up) magma pushes between plates as plates are moving.
This is different from seafloor spreading.

24. HOT SPOTS to VOLCANOES!
An area in the mantle from which heat rises in the form of a thermal plume from deep with the Earth.
Higher heat and lower pressure at the base of the tectonic plate melts rock and forms magma.
The magma rises through the cracks in the crust and erupts to form volcanoes.

25. HOT SPOTS to VOLCANOES!
As the tectonic plate continues to move the volcano breaks away from the hotspot and moves along with tectonic plate.
This allows new volcanoes to form in that area.
The tectonic plate motion results in chains of volcanoes forming.

26. Why do we care?
Millions of people live near areas of high earthquake/volcanic activity.
They have suffered personal and economic losses due to this extreme activity.

27. Earthquake Problems
There is evidence to suggest that tectonic activity contributed to the demise of ancient civilizations.
Based on locations scientist have developed models to show how vulnerable our civilizations today are to this same demise.
Seismic activity can cause buildings and bridges to collapse trapping and killing millions of people.

28. Earthquake Problems
Modern populations tend to be more densely packed with large numbers of tall buildings.
This infrastructure poses a major danger to our ability to survive.
Technology has developed significantly and arichtechs and engineers have been able to make buildings more pliable causing them to bend rather than break.
This has saved millions of lives and billions of dollars.

29. Volcano Problems
Above sea volcanoes (aka where people live) tend to erupt explosively and violently.
Local Effects: Personal property damage, personal injury, DEATH, destruction of buildings, disruption of water supplies, contamination of food sources, landslides, and lack of breathable air.
Global Effects: changes in weather and climate, aviation safety hazards, tsunamis if volcanic eruptions is under or near oceans, seismic activity as a result, and production of acid rain

30. What can WE do?
We can’t predict Earthquakes; we typically will have SOME warning when volcanoes will erupt.
Evacuations can be optional or mandatory.
Houses:
Constructed in such a way that all vents can be closed blocking out all air from the outdoors.
Windows and doors should be properly insulated.
THIS DOES NOT MEAN YOUR HOUSE WILL SURVIVE A VOLACNIC ERUPTION.